Diet is a useful way of controlling CKD and helping your
cat cope
better with the disease. This pagediscusses which foods to feed. It contains
information on therapeutic kidney diets, including what to do if your cat
refuses to eat the
diet which your vet recommends.
It also discusses other food options, i.e.
non-therapeutic
commercial cat foods and homemade foods, and what to feed
if your cat has another health problem with particular dietary requirements.
There is also information on
certain foods which are not suitable for cats.
Please also read the
Nutritional Requirements page for more information on
feline nutritional needs, such as the role of protein.
The Best Food for a CKD Cat...
...is a food that the cat will
eat. I'm not trying to be flippant here. You can source the most expensive,
organic, wholesome food on the planet, but if your cat would rather
starve than eat it, it is of no use whatsoever.
It is not only I who thinks it is more important that a
cat eats than that a cat eats certain foods.
Nutritional management of renal disease
(2008) Sturgess K Presentation to theWorld Small Animal Veterinary Association World
Congress says "It is vital that the cat eats something, as body protein catabolism will
have more serious adverse effect on CRD than almost any diet."
11 guidelines for conservatively treating chronic
kidney disease (2007)
Polzin D
Veterinary MedicineDec 2007 makes the shocking
observation that "in
many or most dogs and cats with chronic kidney disease, death or euthanasia
results directly or indirectly from starvation."
Are you going to let your cat
starve to death? I doubt it! So please read below about the best food
choices and try to feed them, but if your cat refuses to eat them, alternatives
are discussed too. Bottom line, your cat is going to eat!
Food Choices and Controversies
There is an amazing variety of opinions on what is the
best food for healthy cats, and many of those opinions are strongly held. I sometimes get e-mails reproaching me for not
advocating feeding x, y or z food.I've been told I'm condemning cats to death for not insisting my
readers feed raw. Apparently
even looking at a food containing by-products means I am heading for eternal
damnation. I get referred to various
websites, all of which I'm already familiar with, and none of which, whilst
they may have some good points, convinces me that they have discovered the
Holy Grail of feline nutrition.
It all reminds me of some kind of fundamentalist religion.
My way good, your way bad. Please! We're talking cat food here, not the
meaning of life. There are not that much research into feline nutritional
requirements (fortunately this is slowly changing), so many of the claims out there are simply personal
opinion and prejudices. People love certain brands. They hate others.
Big names are suspect. Small brands are great. This despite the fact that
both may have their food manufactured in the exact
same factory, by the exact same methods, using the exact same people and
machinery and even in some cases the exact same ingredients, as came to
light during the 2007 US food recall scandal.
Remember, if there were one perfect food for
healthy cats
out there, we would all be feeding it, and all the manufacturers who didn't make
it would go bankrupt. But there is no such food, so we
must just do the best we can.
Like everybody else, I have my prejudices. But unlike
many others out there, I'm not trying to sell you anything. I've simply
spent twenty years researching CKD and I try to present everything as impartially
as I can.
This website focuses on the nutritional needs of CKD
cats. You may need to put your preferences for a "good food" aside and
accept that quite often with a CKD cat:
just getting any food into your cat is an encouraging
start;
getting him/her to eat a food appropriate for the CKD is
an achievement; and
feeding foods you think are "good" is a bonus.
I've had three CKD cats. I know the stress and guilt of
the diagnosis — and no, you didn't cause the CKD by the foods you chose to
feed to your cat. Let me repeat that, because so many people fret about
this. Your food choices for your cat did not cause CKD. I also know the stress and worry of trying to get food
into a CKD cat. I'm not going to give you a guilt trip on top of that. If
brand A is apparently loathed but has a
food my cat loves, that's good enough for me. My cat doesn't care. She
doesn't do marketing and hype. She just eats. And when she eats, I feel very
relieved, and very happy.
When it comes to food, here is what
I recommend for CKD cats:
Therapeutic kidney diets are proven
to have benefits for CKD cats. I would definitely feed one of these foods if
my cat would eat it, though in earlier stage CKD I would probably not feed
the food exclusively, or would supplement it with additional nourishment
(there is more on this below).
You should try to feed a food as
low in phosphorus
as possible. High
phosphorus levels will make your cat feel bad and will make the CKD progress
faster. Because this is so important, I've created
tables
of commercial foods in order of phosphorus
content for the US market.
The need for a
reduced protein food is much debated, at least in the early stages of CKD (IRIS
Stage 1 and early Stage 2). See
Nutritional Requirements for more on the low protein debate. You do want to feed a food that is
high quality protein
(which in terms of CKD does not actually mean what you probably think it means).
Ideally feed a canned food, because this helps with
problems such as dehydration. If your cat is a dry food junkie, you may
be able to gradually switch him or her over
to wet food. If you can't, don't sweat it. It's
more important that your cat eats than that s/he eats a wet food. If your
cat is prepared to eat a dry therapeutic kidney diet, I would feed that in
preference to a canned non-therapeutic diet (though see point 1 in this
list).
I don't really like complicated cat
foods. I'm not a fan of all those foods containing yummy fruits and
vegetables. They are marketed to appeal to you,
but your obligate carnivore
feline doesn't need them from a nutritional perspective. But if they are the
only foods your cat likes, don't stress over it.
Having said
that, I can't get too excited about
"bad" ingredients. Who decides what is bad anyway? The Cat Food
Police? There are certainly some
ingredients I consider complete no-nos, such as onion and garlic, but that
is for valid medical reasons (see
below).
Most of the other stuff, quite frankly, is a matter of personal choice. If I
had a choice of feeding my cat a food she loved that contained by-products,
for example, or letting her starve to death, the by-products would win every
time.
Feed
a food your cat will eat! Even at the best of times, cats
eat to live rather than live to eat. If you only provide a food your cat
doesn't like, s/he will not eat it, especially if s/he is feeling poorly.
Getting food into your cat is more important than letting him/her
starve to death for your principles or because your cat is "only supposed to
eat the therapeutic diet.".
So remember your new mantra: my cat must eat!
Therapeutic Kidney Diets
Most vets will initially recommend that you feed a
therapeutic kidney diet, and there are valid reasons for this. This section
discusses the various therapeutic diets that are
available, how they can help your cat, how to introduce these foods, and
what to do if your cat won't eat them. It also explains why you
should not feed therapeutic kidney foods exclusively to other family cats.
Everybody seems to know that these
foods have reduced protein levels, and some people are aware that they also
have reduced phosphorus levels. People therefore sometimes think that if
they feed a commercial food that is relatively low in protein and/or
phosphorus, they have replicated a
therapeutic kidney diet.
Unfortunately this is not the case, because there is a lot
more to therapeutic CKD diets than reduced protein and/or low phosphorus
levels.
Staged management of chronic kidney disease in dogs
and cats (2009) Polzin D Presentation to the World Small
Animal Veterinary Association World Congress says "A common
misconception is that renal diets are simply “low protein diets.” Renal
diets encompass a variety of modifications beyond just a limitation of
protein content, and, indeed, the principal beneficial effects of these
diets may not accrue from their protein content. Thus, simply replacing a
renal diet with a standard manufactured diet that is lower in protein
content does not meet the guideline of feeding a renal diet. Since
inappropriate diets can exacerbate clinical signs of uremia and/or promote
progression of CKD, cats and dogs with CKD should be fed a renal diet."
So how do therapeutic kidney diets
differ from non-therapeutic diets?
Diagnostic staging and management of dogs and cats
with chronic kidney disease (2012)
Ross SJ Presentation to the Australian Veterinary Association NSW Annual
Regional Conference states "Compared to adult maintenance diets, diets formulated specifically for
dogs and cats with chronic kidney disease typically have reduced protein,
phosphorus, and sodium content; increased potassium, B-vitamin content and
caloric density; a neutral effect on acid-base balance; and an increased
omega-3/omega-6 polyunsaturated fatty acid (PUFA) ratio."
You can read about all of these
dietary components and why they are important to CKD cats
on the Nutritional Requirements
page, but here is a brief overview:
Caloric Density
Therapeutic kidney diets have a relatively high
calorie content.
You can check the calorie content of some US foods
here (canned) and
here (dry).
Protein
It is true that these foods
are relatively low in
protein.
Prolonging life and kidney function
(2009) Chew DJ & DiBartola SP CVC in
Kansas City Proceedings states that the protein in most of these diets
is reduced by a third to a half. However, the key word there is
"relatively": it does not mean these foods are
too low in protein. On a
dry matter analysis basis, most
therapeutic kidney diets contain 28-35% protein, which is above the 26%
minimum level of protein required by AAFCO for a food to be considered a
complete adult food. As you can see from the
food data tables, there are
quite a lot of commercial non-therapeutic foods with a protein level as low
as this, yet nobody refers to them as low protein foods.
What
is important for CKD cats is that the protein is high quality protein.
I hear from people quite regularly who say that they think many therapeutic
kidney diets contain poor quality ingredients, so how can the protein within them
be considered high quality? I explain more about high quality protein from a
CKD perspective below.
Phosphorus
Therapeutic kidney diets are also relatively low in
phosphorus.
Prolonging life and kidney function
(2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings
states that the phosphorus level in these foods is reduced by 70 to 80%, but
again, this does not mean levels are too low.
In contrast to the protein debate, nobody disputes the
need to keep the phosphorus levels in foods fed to CKD cats as low as
possible. Phosphorus is a
mineral essential for good health which is contained in
many foods. The body is very good at regulating
its phosphorus levels by removing excess phosphorus via the kidneys.
However, the kidneys of a CKD cat can no longer
efficiently excrete excess phosphorus, so the vast
majority of CKD cats will develop
levels of phosphorus in their blood which are too high,
which can make the cat feel ill and make the CKD progress faster. If
you feed foods with a lower phosphorus content, this reduces the workload on
the cat's damaged kidneys and reduces the risk of phosphorus levels in the
cat's body rising too high.
Ideally, as mentioned by Dr
Scott Brown in Management
of feline chronic renal failure (1998) Waltham Focus
8(3), you want your cat to eat food with less than 0.5%
phosphorus
on a dry matter analysis basis.
In practice, most therapeutic kidney foods have a
phosphorus level of around 0.4-0.7%, so many of them are
above the AAFCO minimum for healthy adult cats of 0.5% on a dry matter
analysis basis.
Essential Fatty Acids
These foods contain increased levels of
essential
fatty acids, which appear of increasing importance in the treatment of
CKD.
Potassium
Therapeutic kidney diets have added
potassium,
usually in the form of potassium citrate because this can help with
metabolic acidosis. According to
Prolonging life and kidney function
(2009) Chew DJ & DiBartola SP CVC in Kansas City Proceedings,
dry CKD therapeutic foods have approximately twice as much potassium as
standard dry cat foods.
I often hear from people who have
little enthusiasm for choosing foods from major cat food manufacturers, or
who may not have been feeding their cat a commercial diet of any kind, and they are often
surprised to hear that if I had a CKD cat, I would try to persuade him or
her to eat a therapeutic kidney diet. This is because therapeutic kidney
diets are one of the few treatments with strong evidence that they
are of benefit to CKD cats. Research
indicates that therapeutic diets may:
slow the progression of kidney disease;
reduce the incidence of crises (which usually include
vomiting and appetite loss and which in the worst case may manifest
themselves as
crashing); and
even extend life.
In one older
study,
Survival of cats with naturally occurring chronic renal failure: effect of
dietary management
(2000) Elliott J, Rawlings JM, Markwell PJ, Barber PJ
Journal of Small Animal Practice41 pp235-42, 29 cats were fed
a reduced protein, low phosphorus therapeutic kidney diet, while a further 21 cats
did not eat this diet. Some of the cats (presumably in both
groups) were also given phosphorus binders. The cats fed the therapeutic
kidney diet
survived longer than the other cats, but it is not clear whether this was
due to the reduction in phosphorus intake rather than the reduction in
protein intake. The study concluded "Feeding a veterinary clinical diet (with intestinal
phosphate binders where necessary) specifically formulated for feline renal
failure was associated with a highly significant beneficial effect on
survival of cats presenting with naturally occurring stable CKD. This is the
first prospective dietary study involving naturally occurring feline CKD
cases where survival from first diagnosis has been assessed."
A later study,
Retrospective study of the survival of cats with
acquired chronic renal insufficiency offered different commercial diets
(2005) Plantinga EA, Everts H Kastelein AM & Beynen AC Veterinary
Record157(7) pp185-187, looked at CKD cats who had been fed
therapeutic kidney diets (seven different foods were fed during the study).
The cats fed a therapeutic kidney diet survived for more than twice as long
as the cats given non-therapeutic diets (16 months versus 7 months). The
diet fed to the cat who survived the longest (23 months) contained a
relatively high level of
essential
fatty acids (the food in question was apparently Specific Kidney Support).
In this non-randomised, non-double-blinded study, the cats could be fed a
non-therapeutic diet for up to 25% of the time.
(2006)
Ross SJ,
Osborne CA,
Kirk CA,
Lowry SR,
Koehler LA,
Polzin DJJournal of the American
Veterinary Medical Association229(6) pp949-57 was a
double-blinded randomised study
which found that feeding a therapeutic kidney diet helped to keep
BUN
levels lower and appeared to help prevent
metabolic acidosis
in cats with more advanced CKD. The study concluded "The renal diet
evaluated in this study was superior to an adult maintenance diet in
minimizing uremic episodes and renal-related deaths in cats with
spontaneous stage 2 or 3 CKD." By Stages 2 and 3, they are referring to
cats with creatinine between 2.1 and 4.5 mg/dl or 185 and 400 µmol/L
(which is not exactly the same range as the IRIS staging system). In this
two year study, 22% (five) of the cats eating a standard commercial food
died, but none died in the group eating a therapeutic kidney diet. The
therapeutic food used (Hill's k/d) contained 28% protein and 0.5%
phosphorus on a DMA basis, while the non-therapeutic food contained 46%
protein and 0.9-1.0% phosphorus on a DMA basis. The cats were deemed to be
eating the therapeutic kidney diet if 85% of their food intake came from
this source. Despite the differences in the phosphorus levels in the
foods, there was no difference in
parathyroid hormone levels between the two groups of cats.
The kidney patient: what's for dinner?
(2010) Francey T Presentation to theWorld Small Animal
Veterinary Association World Congress states "The
administration of a renal diet to dogs and cats with CKD stages 2 and 3
markedly prolonged their renal and overall survival, it decreased the rate
of decline of renal function, and it delayed the onset of uremic crises.
These findings, although they don't answer the central question of the
mechanism of protection, clearly show the value and the benefit of early
dietary intervention in animals with CKD. In summary, we now know that dogs
and cats with CKD stages 2 and 3 benefit from receiving a renal diet, but we
do not know: 1) whether earlier intervention would be more beneficial; 2)
whether all renal diets are equal in efficacy; and 3) what in the renal diet
is truly beneficial."
I know, I know, some of you are still muttering "but I hate the quality of
these foods." It is entirely up to you whether you use therapeutic kidney
diets, and it may actually be too early for your cat to start one (see
below), but
please do keep an open mind. Some members of Tanya's CKD Support Group
have also been reluctant to use therapeutic kidney diets, but quite a few
of them have changed their minds, for the simple reason that their cats
feel better on these diets. They have also found that it
saves them time and effort because they have been able
to cut down on giving supplements to their cats, such as phosphorus
binders or essential fatty acids, because the food meets their cats'
requirements without additional supplementation.
BalanceIT has
a video about nutritional requirements in kidney disease.
There are severalbrands available in
the USA which in principle require a prescription. There are also a couple
of foods intended for CKD cats which do not require a prescription. Most of
the foods are available in both canned and dry versions. See
Obtaining Supplies
Cheaply for online suppliers in the USA at reduced prices, including
suppliers who will allow you to purchase single cans so you can ensure your
cat likes a food before buying a lot of it.
Blue Natural Veterinary Diet
Contains lots of vegetables
(unnecessary for CKD cats)
and some questionable ingredients such as
parsley (a diuretic),
cranberries, and alfalfa.
None of these is recommended for CKD cats.
Rayne Clinical Nutrition Adult Health RSSis a
multitasker that apparently is suitable for both urinary tract health (both
struvite and calcium oxalate crystals) and early non-proteinuric kidney
disease. This is unusual, because foods suitable for struvite crystals are
not usually suitable for CKD cats.
Darwin's Intelligent Design Kidney Support
This is a
raw food diet which contains lots of
vegetables (unnecessary for CKD cats) and some questionable ingredients such
as
parsley and
dandelion (diuretics),
cranberries, and
cod
liver oil. None of these is recommended for CKD cats. Darwin's
also refuses to engage with me so I do not know the phosphorus level.
Although these foods require a prescription in theory,
you may well be able to obtain them from some sources without a prescription. Be
sure you understand the pros and cons of these foods and tell your vet if
you are using them.
No Prescription Required
Veterinary Select Neo
Formerly Hi-Tor Neo. They do not respond to my enquiries so the data
provided are very old, but this product is apparently being discontinued
anyway.
Forza10 Renal Active
Contains
some questionable ingredients such as
dandelion and rosemary (diuretics) and
cranberries, neither of which is recommended for CKD cats. They do not
respond to my enquiries so I do not know the phosphorus levels.
introduced
a new range of "phosphorus-focused" foods in 2022. Weruva is a popular brand
but personally I think these foods are too high in protein for a cKD cat.
Here are lists of the composition of
the various diets available on a dry matter analysis basis
(the calories are as fed for the canned food and per kg ME for the dry).
You want your cat to eat food with less than 0.5%
phosphorus or as close to that as you can get.
Therapeutic
Kidney Wet Foods USA
Brand and Variety
Phos %
Protein %
Sodium %
Fat
%
Carbs %
Cals per
oz
Data Obtained
Weruva WxTilapia & Chicken
Purée
0.28
58.30
0.59
38.80
0.00
28.33
27 Sep 22
Weruva WxTilapia & Tuna Purée
0.32
62.40
0.65
34.10
0.40
26.33
27 Sep 22
My Perfect Pet
Low Phosphorus Chicken Carnivore
Grain-Free Blend
0.35
47.10
0.30
14.50
na
51.00
26-Jan-20
Weruva WxChicken & Tilapia in Gravy
0.35
69.00
0.51
34.60
0.00
27.00
27 Sep 22
Purina
Pro Plan Veterinary Diets NF Kidney
Function
Advanced Care
0.39
27.80
0.34
22.12
36.98
30.00
15-Jan-20
Dave's Pet Food
Restricted Diet Protein-Phosphorus
Chicken Lickin' Good˛
0.39
45.15
0.14
22.07
19.59
30.55
07-Nov-19
Weruva Wx
Chicken Purée
0.39
61.60
0.45
33.30
1.50
26.00
27 Sep 22
Weruva Wx
Chicken in Gravy
0.42
68.10
0.45
36.60
0.00
27.00
27 Sep 22
Purina
Pro Plan Veterinary Diets NF Kidney Function
Early Care
0.43
39.49
0.39
19.10
31.49
29.45
15-Jan-20
Royal Canin
Veterinary Diet Renal Support D
(Delicious)
0.44
34.21
0.49
34.21
22.24
32.33
28-May-21
Hill's
Prescription Diet k/d with Tuna
0.45
29.00
0.24
22.10
41.70
30.91
01-Feb-20
Royal Canin
Veterinary Diet Renal Support E (Enticing)
(pâté)
0.46
33.59
0.25
29.59
27.32
29.48
03-Apr-20
Royal Canin
Veterinary Diet Renal
LP Modified (pâté)
Royal Canin
Veterinary Diet Renal Support T
(Tasty)
0.51
31.64
0.51
28.81
30.23
27.33
03-Apr-20
Blue
Natural Veterinary Diet KM Kidney
+
Mobility Support
0.55
29.11
0.3
20.97
na
na
05-Feb-20
Rayne Clinical Nutrition Adult Health RSS
0.58
54.09
0.67
21.06
18.78
25.45
27-Nov-19
Hill's
Prescription Diet k/d Early Support
Chicken,
Vegetable & Rice
0.59
34.10
0.27
24.10
34.50
27.24
01-Feb-20
Hi-Tor
Veterinary Select Neoą
0.72
36.54
0.43
43.18
na
na
24-Jul-14
Forza10
Renal Sensitive + Active Grain-Freeą ˛
na
31.82
na
35.45
na
30.40
31-Jan-20
DarwinsIntelligent Design Kidney
Support Rawą˛ ł
na
48.00
na
40.00
6.00
46.00
22-Jan-20
na = not available
ą They do not respond to my repeated enquiries.
˛
Levels are
minimums.
ł
I do not recommend raw diets for CKD cats, see
below
Therapeutic
Kidney Dry Foods USA
Brand and Variety
Phos
Protein
Sodium
Fat
Carbs
Cals
Obtained
Purina
Pro Plan Veterinary Diets NF Kidney Function
Advanced Care
0.39
30.40
0.31
18.21
41.94
4085
10-Jan-20
Purina Pro Plan Veterinary Diets NF Early Care
0.41
38.92
0.31
15.24
36.40
4041
10-Jan-20
Farmina VetLife Renalą
0.43
26.20
na
21.39
na
4070
31-Jan-20
Royal Canin Veterinary Diet Renal Support S
(Savory)
0.44
25.78
0.44
22.60
41.36
4061
03-Apr-20
Royal Canin
Veterinary Diet Renal Support A
(Aromatic)
0.45
24.14
0.37
17.84
46.18
3790
03-Apr-20
Royal Canin
Veterinary Diet Renal Support F
(Flavorful)
0.46
27.13
0.41
17.73
43.41
3811
03-Apr-20
Hill's
Prescription
Diet k/d + Mobility
0.50
28.90
0.27
22.00
42.90
4155
01-Feb-20
Hill's
Prescription
Diet k/d with Ocean Fish
0.52
29.80
0.26
23.10
40.60
4235
01-Feb-20
Hill's
Prescription
Diet k/d
0.52
30.00
0.26
23.00
40.80
4239
01-Feb-20
Hill's
Prescription
Diet k/d Early Support Chicken
0.56
34.00
0.25
21.00
38.40
4203
01-Feb-20
Royal Canin
Veterinary Diet Multifunction Renal
Support
+ Hydrolyzed Protein (for
cats with both CKD and food allergies)
0.70
29.35
na
19.57
na
3958
15-Jan-20
Forza
10 Renal
Activeą ˛
0.87
28.26
0.26
20.11
na
3837
31-Jan-20
Rayne
Clinical Nutrition Adult Health RSS
0.94
35.54
0.72
14.49
40.33
3887
27-Nov-19
na = not available
ą They do not respond to my repeated enquiries.
˛
Levels are minimums
Hill's produces a variety pack
containing a mix of dry and wet kidney foods so you can see which flavours
your cat prefers. Royal Canin also used to produce such a pack and one
member of Tanya's CKD Support Group found it at her local PetSmart for US$9.99,
but it is no longer on the Royal Canin website so it may have been
discontinued.
Amazon sells the Royal Canin renal support
starter kit, though it is currently (June 2020) unavailable.
Adobe Animal Hospital in Los Altos,
California, sells the Royal Canin starter kit locally. A prescription
is required.
Alternatively, you could buy a variety of therapeutic kidney foods
from a supplier such as
Chewy, and then place a larger order once
you
know which food your cat prefers.
Chewy
allows you to check the ingredients of many cat foods, both therapeutic and
non-therapeutic.
If your cat does not like a particular therapeutic kidney
food, many brands will allow you to return the food for a full
refund.
UK Therapeutic Kidney Diets
There are
fourbrands available in
the UK which in principle require a prescription. There are also a number of foods
designed for CKD cats which do not require a prescription. Most of the foods
are available in both canned and dry versions.
See
Obtaining
Supplies Cheaply for online suppliers in the UK at reduced prices, most
of which do not require a prescription.
Forza10
Contains
some questionable ingredients such as
dandelion (diuretic) and
cranberries, neither of which is recommended for CKD cats. They do not
respond to my enquiries so I do not know the phosphorus levels.
You want your cat to eat food with less than 0.5%
phosphorus or as close to that as you can get.
Therapeutic
Kidney Wet Foods UK
Brand and Variety
Phos
%
Protein %
Sod
%
Fat
%
Carbs
%
Cals per oz
Data Obtained
Royal Canin Veterinary Diet Renal with Chicken Pouch
0.30
34.80
0.40
34.80
21.70
na
05-Jun-20
Royal Canin Veterinary Diet Renal Can
0.40
33.33
0.40
28.90
24.40
na
05-Jun-20
Royal Canin Veterinary Diet Renal with Beef Pouch
0.40
34.00
0.40
33.00
23.00
na
05-Jun-20
Beaphar Kidney Diet with Chicken Breast
0.40
36.00
0.40
40.00
na
na
09-Jun-20
Beaphar Kidney Diet with Pollock
0.40
36.00
0.40
40.00
na
na
09-Jun-20
Beaphar Kidney Diet with Duck
0.40
36.00
0.40
40.00
na
na
09-Jun-20
Beaphar Kidney Diet with Lamb
0.40
36.00
0.40
40.00
na
na
09-Jun-20
Beaphar Kidney Diet with Taurine
0.40
36.00
0.40
40.00
na
na
09-Jun-20
Hill's Prescription Diet k/d + Mobility with Chicken Pouch
0.41
29.40
0.26
23.00
39.90
26.80
05-Jun-20
Hill's Prescription Diet k/d with Beef Pouch
0.41
29.70
0.26
22.20
40.00
25.80
05-Jun-20
Hill's Prescription Diet k/d with Chicken Pouch
0.42
29.70
0.26
22.00
40.40
25.80
05-Jun-20
Purina Pro Plan
Veterinary Diets NF St/Ox Renal
Mousse Can
0.43
31.06
0.43
47.66
11.49
na
08-Jun-20
Royal Canin Veterinary Diet Renal with Tuna Pouch
0.45
33.00
0.40
30.00
24.50
na
05-Jun-20
Vet-Concept Low Protein
0.45
35.45
0.36
35.45
19.50
na
09-Jun-20
Integra Protect Renal Salmon Foil Tray
0.48
25.20
0.70
52.20
10.40
na
09-Jun-20
Specific FKWą
0.48
34.26
0.28
43.25
na
na
15-Oct-15
Hill's Prescription
Diet k/d Stew with Chicken
& Vegetables can
0.49
30.00
0.24
24.00
39.60
23.83
05-Jun-20
Hill's Prescription Diet k/d Early Stage with Chicken
0.50
33.60
0.29
23.10
35.00
26.08
05-Jun-20
Hill's Prescription Diet k/d with Salmon Pouch
0.51
29.90
0.28
23.20
38.90
26.65
05-Jun-20
Purina Pro Plan
Veterinary Diets NF Renal
Tender Pieces in Gravy with
Chicken Pouch
0.52
32.61
0.30
40.87
17.39
na
08-Jun-20
Purina Pro Plan
Veterinary Diets NF Renal
Tender Pieces in Gravy with
Salmon Pouch
0.52
32.61
0.30
40.87
17.39
na
08-Jun-20
Royal Canin Renal Liquid
0.53
46.67
0.53
36.67
6.61
na
09-Apr-20
Dr Clauder's Kidney Diet
0.55
30.00
0.21
34.14
na
na
05-Jun-20
Concept for Life Vet Diet Renal
0.55
30.00
0.45
45.45
na
na
08-Jun-20
Integra Protect Renal Pure Turkey Can
0.57
33.30
0.76
38.10
17.60
30.62
09-Jun-20
Sanimed Renal
0.59
28.89
0.37
37.78
na
na
05-Jun-20
Kattovit Niere/Renal Beef pouch
0.60
30.00
0.75
27.50
na
na
08-Jun-20
Kattovit Niere/Renal Chicken pouch
0.60
30.00
0.75
27.50
na
na
08-Jun-20
Kattovit Niere/Renal Turkey pouch
0.60
30.00
0.75
27.50
na
na
08-Jun-20
Trovet Renal & Oxalate RID Chicken Can
0.61
33.04
0.35
34.78
23.48
32.21
08-Jun-20
Trovet Lamb Renal & Oxalate RID Lamb Can
0.61
33.04
0.35
35.22
23.91
32.55
08-Jun-20
Trovet Renal & Oxalate RID Lamb Pouch
0.61
33.04
0.35
35.22
23.91
32.55
08-Jun-20
Integra Protect Renal Chicken Can
0.65
32.50
1.20
42.50
12.50
31.75
09-Jun-20
Trovet Renal & Oxalate RID Chicken Pouch
0.68
29.55
0.68
27.27
na
28.66
08-Jun-20
Integra Protect Renal Beef Can DISC?
0.70
32.50
1.45
42.50
12.50
30.01
09-Jun-20
Integra Protect Renal Chicken Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Integra Protect Renal Beef Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Integra Protect Renal Duck Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Integra Protect Renal Pure Turkey Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Integra Protect Renal Pork Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Integra Protect Renal Veal Foil Tray
0.70
33.90
0.74
45.70
10.90
36.00
09-Jun-20
Smilla Veterinary Diet Renal Foil Tray
0.70
33.91
0.74
45.65
na
na
08-Jun-20
Eukanuba Renal Formula for Cats
0.78
25.49
0.51
29.41
na
na
11-Jun-20
Kattovit Niere/Renal Lamb tin
0.78
34.78
0.35
43.48
na
na
08-Jun-20
Kattovit Niere/Renal Chicken tin
0.78
34.78
0.35
43.48
na
na
08-Jun-20
Kattovit Niere/Renal Fish tin
0.78
34.78
0.35
43.48
na
na
08-Jun-20
Forza10 Renal Sensitive + Active Grain-Freeą ˛
na
31.82
na
35.45
na
30.40
31-Jan-20
na = not available
ą Have not responded to my 2020 enquiries.
˛
Levels are minimums
Therapeutic Kidney Dry Foods UK
Brand and Variety
Phosphorus %
Protein
%
Sodium %
Fat
%
Carbs
%
Calories per kg
Data Obtained
Royal Canin
Veterinary Diet Renal RF23
0.32
24.34
0.42
17.99
38.21
na
09-Apr-20
Vet-Concept
Low Protein
0.37
28.00
0.27
20.90
43.40
na
09-Jun-20
Eukanuba
Renal Formulaą
0.38
30.43
0.49
25.00
na
na
15-Oct-15
Royal Canin
Veterinary Diet Renal Select RSE 24
0.43
25.93
0.48
22.75
32.53
na
09-Apr-20
Sanimed
Renal
0.43
26.09
0.20
21.74
44.89
na
05-Jun-20
Josera Carismo
Adult Senior Renal
0.45
27.00
0.30
20.00
na
4068
09-Jun-20
Specific
FKDą
0.46
25.54
0.21
26.09
na
na
15-Oct-15
Royal Canin
Veterinary Diet Renal Special RSF26
0.47
27.51
0.42
17.99
34.85
na
09-Apr-20
Integra
Protect
0.48
27.70
0.37
26.10
39.90
na
09-Jun-20
Hill's
Prescription Diet with Tuna
0.48
29.20
0,24
20.60
43.50
4099
05-Jun-20
Hill's
Prescription Diet k/d Early Stage
0.48
33.60
0.24
22.60
36.30
4215
05-Jun-20
Happy Cat
Diet Niereną
0.49
25.99
0.22
21.66
na
na
15-Oct-15
Affinity
Advance Renal
Failure
0.49
27.00
0.22
16.80
34.00
na
15 Jun 20
Hill's
Prescription Diet k/d with Chicken
0.49
29.40
0.25
22.60
41.70
4215
05-Jun-20
Virbac
VetComplex Renal
0.50
31.70
0.40
22.20
na
na
05-Jun-20
Hill's
Prescription Diet k/d
+ Mobility with
Chicken
0.52
29.80
0.24
22.60
40.40
4177
05-Jun-20
Pro-Vet
Renal
0.53
26.09
2.28
21.74
na
4360
08-Jun-20
Purina
Proplan Veterinary Diets NF Renal Function
0.53
27.81
0.21
13.37
50.27
3804
08-Jun-20
TroVet
Renal & Oxalate RID
0.54
28.26
0.43
25.54
34.67
na
08-Jun-20
Trovet
Renal Venison RID
Limited Ingredient Diet
0.54
30.27
0.27
20.54
37.49
3903
08-Jun-20
Kattovit
Niere/Renalą
0.70
26.00
0.33
22.00
na
na
15-Oct-15
Forza 10
Renal Active˛
0.87
28.26
0.26
20.11
na
3837
31-Jan-20
Concept for Lifeą
na
na
na
na
na na
na
na = not available
ą Have not responded to my 2020 enquiries
˛
Levels are minimums
Many people buy a variety of therapeutic kidney foods
from a supplier such as
Zooplus, and then place a larger order once they
know which food their cat prefers.
Royal Canin offers a renal palatability pack
containing a mix of dry and wet kidney foods so you can see which flavours
your cat prefers. This may be available from your vet, and is available
online from
Animed Direct
allows you to check the composition of many cat foods, both therapeutic and
non-therapeutic.
When to Start a Therapeutic Kidney
Diet
Therapeutic kidney diets used to be routinely recommended
for all CKD cats. However, in order to avoid weight loss and muscle
wasting in cats with early stage CKD who might not benefit massively from
early dietary changes, it is now usually not recommended to start them too
soon. On the other hand, the longer you leave it, the lower your chances
are of persuading your cat to accept a new food, and your cat would have
less time to benefit from the therapeutic diet.
So when should you start such a diet?
Treatment recommendations for CKD in cats
(2019)
International Renal Interest Society
divides CKD into stages (see
How Bad is
It?)
and suggests starting a veterinary diet in Stage 2, i.e. when the
cat's creatinine is over 1.6 mg/dl or 140 µmol/L. However for cats with
proteinuria,
it states "feed a renal clinical diet" regardless of the stage the cat is
in. It also says that introducing a therapeutic diet "may be accomplished
more easily early in the course of CKD, before inappetence develops."
Another thing to consider when deciding when to introduce a therapeutic
kidney diet is your cat's
BUN
(urea) level. BUN is influenced by protein intake,
so
it does often help the cat feel better if you restrict protein intake as
the CKD progresses.
Prolonging life and kidney function
(2009) Chew DJ & DiBartola SP CVC in
Kansas City Proceedings states "Protein
restriction should be considered when moderate to severe azotemia persists
in the wellhydrated state. The clinician should strike a balance between
reducing protein intake and the animal's willingness to eat... If
possible, the animal should be acclimated to the new diet while its
appetite is still reasonably good."
Generally speaking, once BUN levels are over 60 mg/dl
(urea over 21 µmol/L), you
are more likely to see symptoms such as
vomiting and nausea
and a therapeutic diet
may well help with this.
The study that most experts cite when recommending a
therapeutic kidney diet is
Clinical evaluation of dietary modification for treatment of spontaneous
chronic kidney disease in cats
(2006)
Ross SJ, Osborne CA, Kirk CA, Lowry SR, Koehler LA, Polzin DJ Journal
of the American Veterinary Medical Association229(6) pp949-57.
This study found that feeding a therapeutic kidney diet helped to keep
BUN
levels lower and appeared to
help prevent
metabolic
acidosis
in cats with more advanced CKD. The study concluded "The
renal diet evaluated in this study [Hill's k/d] was superior to an adult
maintenance diet in minimizing uremic episodes and renal-related deaths in
cats with spontaneous stage 2 or 3 CKD." By Stages 2 and 3, they are
referring to cats with creatinine between 2.1 and 4.5 mg/dl (165 - 400
µmol/L international).
So if your cat's creatinine is over 1.6 mg/dl or 140
µmol/L and your cat is eating and not in
crisis (e.g. just returned home from a stay at the vet's), I would
consider starting a therapeutic kidney diet. If your cat's creatinine is
below this level but your cat is stable, I would introduce these foods,
especially if your cat has
proteinuria, so you
know which of them most appeals to your cat, but I would not feed them
exclusively (see
below).
On the other hand, if your cat is underweight or has a very poor appetite,
or is recovering from a crisis, I would wait a while —
Cats Exclusive Veterinary Center
states that it is better not to feed therapeutic kidney diets to thin cats or cats
with poor appetites. You should always address possible causes of
inappetence, such as
nausea or
anaemia, before trying to
persuade your cat to eat a therapeutic kidney diet.
I occasionally hear from people with a young CKD cat,
maybe even a kitten. It may not be wise to feed a therapeutic kidney diet
to a kitten, who is still growing and therefore needs a higher protein
intake for growth and a higher phosphorus intake for proper bone
formation. Talk to your vet about this.
How to Introduce a Therapeutic Kidney Diet
It is better to get your cat used to a therapeutic
kidney diet
while his/her appetite is still relatively healthy, rather than trying to
effect a switch at a time when your cat feels poorly. If your cat is not
eating voluntarily, don't rush to introduce a therapeutic kidney diet.
Feeding cats with different nutritional needs: a
dilemma in the multicat household
(2012) Scherk M
Presentation to the 73rd SCIVAC International Congress 2012 says on
page 424 "Protein is a preferred
flavour, so if a cat is already inappetent, restricting protein may result
in inadequate intake of all nutrients, and the protein intake may fall
below that required for normal function."
Instead, take steps to control any issues which may be causing
your cat to feel sick or have no appetite (see
Index of
Symptoms and Treatments)
before
trying to introduce a therapeutic diet — the cat may associate feeling sick
with the food and refuse to eat it at all; whereas if you had waited until
the cat felt a little better, you might have been more successful. This is
particularly important if your cat is diagnosed following a crisis and is
still under the weather.
11 guidelines for conservatively treating chronic
kidney disease
(2007) Polzin D
Veterinary MedicineDecember 2007 says "Force-feeding
new diets, exposing patients to new diets while hospitalized, or
administering medications or other unpleasant events during and around
feeding times should all be avoided. A renal diet should be introduced to
patients gradually."
Marks S World Small
Animal Veterinary Association World Congress 2001 says that it is also
better for cats not to introduce any food too quickly because cats are
creatures of habit when it comes to food, so introducing it suddenly may
reduce your chances of success.
Some cats do actually like therapeutic kidney diets (ironically, they
are often other family cats who are healthy and do not need them!). If you
happen to have a cat who likes the therapeutic diet, it is still better
not to try to switch your cat over in one fell swoop, because a sudden
change of food may cause
Instead, mix a little of the new food with your cat's
favourite food to start with, and gradually increase the proportion of the
new food, over a period of several days or even weeks.
There is no need to rush the introduction of any new food,
therapeutic or otherwise, go at your cat's pace.
Dietary considerations in dogs and cats with kidney
disease
(2008) is a video presentation by Dr
CL Langston which says you can take as long as 4-6 weeks to introduce a
therapeutic diet if necessary. Therapeutic kidney diets can be rather dry (even the
canned food varieties), so it may also help to
start with to put a little
tuna
water
(the water in which tuna is packed) on the food to moisten it and
make it taste a little better. You could also try
warming the food. Some people have found puréeing
the canned food makes it more attractive to their cats.
Once your cat is eating a therapeutic kidney diet, ideally this should be
the only food your cat eats.
Your vet should advise you how much of a particular food
your cat needs. You can also look at the brand's website (there are
links
here
to
the various brands) to see how much they recommend, and read
here
about calorie needs.
If you are lucky enough to have a CKD cat who will eat a
therapeutic kidney diet, don't buy too much at first. It is a truth universally
acknowledged that as soon as you buy 24 cans of a food, your cat will refuse
to eat it.
(2015) Fritsch DA & Jewell
DE Veterinary Record Open2(2) is a study by Hill's in which
94% of the cats were successfully transitioned to a dry therapeutic kidney diet.
Once you have begun a therapeutic kidney diet, you need to monitor your cat's
weight and muscle
status.
I would weigh your cat at least once a week (you
can find sources for suitable scales
here)
and also check his or her body condition score.
(2009) Chew DJ & DiBartola SP CVC in
Kansas City Proceedings states
"Maintenance of stable body weight and serum albumin concentration
suggests adequate intake of calories and protein whereas progressive
declines in body weight and serum albumin concentration suggest
malnutrition or progression of disease and are indications to increase the
amount of protein fed."
If you notice any weight loss or if your cat seems less muscular, first
make sure your cat is definitely eating the food, and eating enough of it
—
calories
and total food intake also matter. If s/he is definitely
eating the food, you could speak to your vet about topping up the
therapeutic diet with additional high quality
protein, such as
egg whites.
See
Persuading Your Cat to Eat
for ways to
get additional nourishment into your cat.
If your cat continues to lose weight, speak to your vet about what to do.
It may be that your cat would do better on another therapeutic kidney
food, or may actually need another food, either instead of or in
conjunction with the therapeutic kidney diet.
Feeding cats with different nutritional needs: a
dilemma in the multicat household (2012) Dr M Scherk
Presentation to the 73rd SCIVAC International Congress 2012 says on
page 425 "Just because someone has a specific illness does not
automatically mean that the diet designed for that condition is the best
diet for that individual. Every time we send home a therapeutic diet, we
are performing a feeding trial with one subject in it (n=1). We have to
get the cat back into the clinic and see how he/she is doing on that food.
How is his weight? Increased? Decreased? How is his coat? Does he eat with
enjoyment or vigour? What are his stools like (moist logs or dry pellets,
cow patties or coloured water)? How energetic is he?...If his weight has
decreased, is it because he isn't eating enough of the food we are giving
him or is it because we aren't giving him enough of it? OR (and only once
we have asked the previous questions can we consider this) is it because
his illness has progressed or another illness has arisen." The article
includes a very useful algorithm for what to consider if a CKD cat is
losing weight.
(2010)
Polzin DJ Nestlé Purina PetCare Handbook of Canine and Feline Clinical
Nutrition pp84-89 has an algorithm on page 89 about when and how to
feed a therapeutic kidney diet.
When a Cat Refuses a Therapeutic Kidney Diet
Despite your best efforts, you may fail to persuade your
cat to eat these foods. It can be particularly scary if your vet returns
your cat to you after a session on
intravenous fluids and informs you that if you
cannot persuade your cat to eat the therapeutic diet, you are effectively
killing him or her. Well, I didn't succeed with
Tanya and Thomas, so I'm a failure too. But I know more about it now, so here are some tips.
Firstly, don't try to introduce such a food when your cat
is sick or not eating any food voluntarily — see
above
for more about this. When Thomas was seriously ill after initial diagnosis
and returned home after four days on intravenous fluids (he also had
anaemia, which can cause severe loss of appetite), we fed him whatever he
would eat, and then tried to provide a more suitable diet once he was
stable.
Assuming your cat is stable and is eating non-therapeutic
food, take as long as you need. You can take as long as 4-6 weeks if necessary
to introduce a new food.
Also try a different therapeutic food — some cats love one
brand, but hate the others.
You can find lists above of the various
US therapeutic kidney diets
and
UK therapeutic kidney diets.
Many vets can give or sell you one can of various varieties, so you can try
to find one your cat likes. You can also find retailers who will sell
individual cans
here.
Another solution is to mix the therapeutic food with the
lowest phosphorus food your cat will eat, or to add a topping of something
tempting (see
above
and
Persuading Your Cat to Eat).
Top 5 indications for appetite stimulation
(2020) Cook AK Clinician's BriefJun 2020 pp31-34 suggests
that in some cases it may be worth using an appetite stimulant whilst
transitioning your cat to a therapeutic diet. This is not a strategy I have
really come across before, but you could always discuss this option with
your vet.
I
f you absolutely cannot persuade your cat to eat any of
these foods, please do not feel too despondent. Although the evidence for
feeding a therapeutic kidney diet is strong, it is more important that a cat
eats than that s/he eats nothing. Don't forget, cats with creatinine below
1.6 mg/dl or 140 µmol/L probably do not need a therapeutic kidney diet yet
— The
Merck Veterinary Manual
states "Animals in this stage [IRIS Stages 1 and 2] should be fed
standard, commercially available maintenance diets, unless they are markedly
proteinuric."
Even if your cat has more advanced CKD, starvation is far
more life-threatening. Cats eat to live rather than live to eat, and if they
do not like what is offered, they may simply refuse point blank to eat. This
lack of food intake is particularly worrying
with cats, because cats who do not eat may develop a condition called
hepatic lipidosis (fatty liver disease) where the liver starts to function
abnormally.
Feline hepatic lipidosis: therapeutic considerations(2011) Armstrong PJ
Presentation to the 36th World Small Animal Veterinary Association World
Congress mentions that hepatic lipidosis can develop after only
2-7 days of not eating; and it can be life-threatening. Even if the cat does
not develop hepatic lipidosis, not eating can be a risk. Nutritional management of renal disease
(2008) Sturgess K Presentation to theWorld Small Animal Veterinary
Association World Congress says "It is vital that the cat
eats something, as body protein catabolism will have more serious adverse
effect on CRD than almost any diet."
(2010) Francey T Presentation to theWorld Small Animal Veterinary
Association World Congress states "By
individual coaching most dogs and cats can be switched to renal diets and it
is important to realize that this change should be made slowly over weeks to
months if necessary. In advanced CKD, dietary changes are certainly more
difficult and affected animals are less likely to accept diets to which they
have not been used. Feeding these animals necessitates either a compromise
with more palatable (and less optimal) diets or the use of assisted feeding
strategies including feeding tubes."
(2016)
Sparkes AH, Caney S, Chalhoub S, Elliott J, Finch N, Gajanayake I,
Langston C, Lefebvre H, White J & Quimby J Journal of Feline Medicine &
Surgery18 pp219-239 state "maintaining calorie intake is the
highest priority in CKD and the preferred choice of diet is generally in
the following order: wet renal > dry renal > home-prepared renal diet >
wet senior > dry senior > wet maintenance > dry maintenance. Senior diets
generally have lower protein (and phosphate) than adult maintenance diets
but, in the absence of a renal diet, earlier intervention with a phosphate
binder may be necessary.”
So don't beat yourself up if, after trying your best to
get your stable cat on a therapeutic kidney diet, over a period of several
weeks if necessary, you simply cannot persuade him or her to eat these
foods. You do have to consider your cat's quality of life: would you want to
spend the rest of your life eating a food you detest?
Feeding
cats with different nutritional needs: a dilemma in the multicat household
(2012) Scherk M
Presentation to the 73rd SCIVAC International Congress 2012 says on page
425
"for well-being, the patient should
enjoy the diet offered, regardless of what illness he/she has.
It is always more important that they eat, rather than what they eat."
If necessary, aim for a compromise. You may be able to
persuade your cat to eat a food that s/he enjoys that may
replicate at least some of the benefits of these foods.
Clinical evaluation of dietary modification for treatment of spontaneous
chronic kidney disease in cats
(2006)
Ross SJ,
Osborne CA,
Kirk CA,
Lowry SR,
Koehler LA,
Polzin DJJournal of the American
Veterinary Medical Association229(6) pp949-57 is the study
with the strongest evidence for therapeutic kidney diets, yet even that states
"These findings emphasize the value of considering individual dietary
components in the overall assessment of the benefits of dietary therapy.
Individually or in combination, similar dietary modifications in the
present study may have minimized the number of uremic crises and
mortality rate."
See
below
for tips on choosing
a non-therapeutic diet.
Therapeutic Kidney Diet Issues
A therapeutic diet may not always be the best choice for a cat with
hypercalcaemia (high calcium levels in the blood).
Hypercalcemia in chronic kidney disease
(2018) Van den Broek H International Renal Interest Society
states "When persistent hypercalcemia occurs or is
worsening in a cat fed a renal diet, and no other underlying cause has
been identified, it is advisable to discontinue feeding 100% renal diet.
Either the proportion of renal diet fed on a daily basis could be reduced,
or renal diet could be stopped completely. A dietary transition could then
be made to a diet less stringently phosphate restricted, such as a senior
diet, or to a calcium oxalate prevention diet, which is restricted in
calcium."
If you purchase a US
therapeutic kidney diet, you may note that the packaging says that you are
not supposed to feed these diets for longer than six months, or that they
are for supplementary or intermittent feeding only. This is
because under AAFCO rules these diets are not a complete and balanced diet
for a healthy adult cat - this is deliberate, otherwise they would not
have their therapeutic qualities, such as low phosphorus levels.
Pet Diets
explains more about this (search for "supplemental or
intermittent feeding" and one of the responses addresses this issue), and states that it
is normally in order to feed these foods on an ongoing basis to CKD cats.
Most therapeutic kidney diets contain potassium in the
form of potassium citrate. This is a potential concern if you are using an
aluminium-based phosphorus binder, because products containing citrate may
increase the absorption of aluminium. In practice, most people using
therapeutic kidney diets will not also need to use a phosphorus binder;
but if you need to use both, check
Phosphorus Binders for possible solutions to this problem.
Feeding Therapeutic Kidney Diets to Healthy Cats
It seems that many vets suggest that it is acceptable to
feed a therapeutic kidney diet to other family cats. I do not understand this.
If the food is so potent that it is usually available by prescription only, how
would it miraculously have no effect on other, healthy cats? The answer is
that it will have an effect: non-CKD cats fed a therapeutic kidney diet for any
length of time run the risk of malnutrition, particularly young cats and
kittens, because of the reduced protein content of such foods. In a study
into the use of a
new phosphorus binder which was given to healthy cats,
Efficacy and acceptability of the new oral phosphate
binder Lenziaren in healthy cats fed a standard diet
(2014) King JN, Erasmus HL, , Delport PC, Bester ICJ & Seewald
W BMC Veterinary Research10 258, a therapeutic kidney diet was also fed and the study states "the
choice of baseline in the statistical analyses including group F (renal
diet) was challenging due to the unexpected loss of body weight in the renal
diet group, which was most pronounced in the acclimatization period."
Even for an older cat, it may not be wise to feed a lower protein diet if
the cat is basically healthy.
Feeding the older cat to optimize health and longevity
(2003) Freeman LM A Presentation to the Waltham Feline Medicine
Symposium states "some nutritionists actually
recommend that older cats eat a higher protein level than younger cats. The
jury is still out but for older cats without significant kidney disease, it
is wise to avoid low protein diets unless there is a specific indication
such as severe renal or hepatic disease."
I know it can be tricky feeding a multiple cat household.
One possible solution is to use a feeder that only allows your CKD cat to
eat the food within it (see below for links to such products).
Alternatively, you may have to compromise by leaving out a therapeutic
kidney food for all
the cats when you are out of the house, but feeding the cats separately when
you are home. But do always supplement a non-CKD cat with normal cat food.
Not only is this better for their health, but it will also save you money —
therapeutic diets are expensive.
(2012) Scherk M
Presentation to the 73rd SCIVAC International Congress 2012 pp421-430 is an
excellent article about how to feed family cats with differing needs.
is a pet feeder system that works if a cat is microchipped, though it also
comes with a microchip that you can attach to your cat's collar if necessary. It is a
British product, available directly from the manufacturer in a number of
different countries. One model is also available
from
Amazon UK
and
Amazon USA. You can also buy
collars with RFID chips which act in a similar way.
Non-Therapeutic Diets: Commercial Foods or a Homemade Diet
If you are unable to persuade your cat to eat a
therapeutic kidney diet, you will have to consider
feeding other foods instead.
Although therapeutic kidney diets are often the ideal (see
above),
keeping weight on and your cat eating regularly are
more important. The main options are
non-therapeutic commercial foods
or a
homemade
diet.
Do not introduce any new food
suddenly, follow the guidelines for
When choosing a non-therapeutic diet,
as far as possible you want to
replicate the benefits of a therapeutic kidney diet. Unfortunately it is not
known exactly what is in the therapeutic kidney diets that makes them so
effective, and these foods themselves vary in their composition. You can read more about their main features
above.
Even if you do nothing else, aim to feed a food as low in
phosphorus as you can. See the
Phosphorus page for more
information on why this is so important.
I
deally, as mentioned by Dr
Scott Brown in Management
of feline chronic renal failure
(1998) Waltham Focus
8(3), you want your cat to eat food with less than 0.5% phosphorus
on a dry matter analysis (DMA) basis. In practice, you are unlikely to find any complete
adult cat foods
in the USA with a phosphorus level lower than 0.5% because that is the
minimum phosphorus level required by AAFCO.
Of course, you also
need your cat to eat. Therefore you may have to
have a less ambitious goal, at least to start with, of, say, feeding a food
with less than 0.75% or maybe even less than 1% phosphorus. If
your cat's phosphorus levels (as shown in blood tests) are not too high, you
have a bit more room for manoeuvre.
But the ultimate aim is to feed your cat a food containing as little
phosphorus as possible.
(2015) A Presentation to the
Virginia Veterinary Medical Association 2015 Virginia Veterinary
Conference, Dr D Chew has a very useful
algorithm on how to
control phosphorus levels via food and
phosphorus binders.
If you think you have found a food which is low in
phosphorus, please be sure that you are looking at it on a
dry matter analysis basis
(DMA) basis. The labels on cans
usually do not provide information on a DMA basis, so that
apparently low level of phosphorus is unfortunately
unlikely to be accurate. For this reason I have
created tables of many US foods showing their phosphorus levels
(see below).
High Quality Protein
During the breakdown of dietary protein in the digestive process,
waste substances are created which are filtered out of
the blood by the kidneys and excreted via
urination. This is sometimes referred to as the removal of
nitrogenous wastes.
Unfortunately damaged kidneys find
it harder to do this, which is why
blood urea
nitrogen (BUN)
levels rise in CKD.
Therefore the goal is to feed a
protein with the correct balance of amino acids to provide the cat with the
ability to maintain and repair bodily tissues but in a form which needs as
little breaking down as possible. That is what we mean in this context by
"high quality protein." Proteins of this nature are sometimes referred to as
having a "high biologic value." The food with the highest biologic value is
actually
eggs.
Some people criticise the quality of
the protein in therapeutic kidney diets. These foods may not have the type of
protein that you would consider high quality for yourself (e.g. organic
chicken breast) but the manufacturers do spend a lot of money trying to
create foods that are relatively low in protein but which contain high
quality protein from the CKD perspective, and studies do indicate that they
tend to achieve this goal.
You can
compare the phosphorus levels in commercial foods to those in therapeutic
kidney diets quite easily because it is simply a matter of percentages; but
it is harder to compare the protein levels in foods because you cannot
easily measure biologic value. Therapeutic
kidney
diets have a protein content of around 28-35% on a DMA basis, so when choosing
a commercial food, I would advise at least trying to find one with
protein around this level and with meat rather than grain proteins; but the fact remains that
if you are feeding a non-therapeutic kidney diet, you are unlikely to be able to determine
whether you are feeding high quality protein from a CKD perspective.
Not all CKD cats need additional
potassium
but if yours does, your vet can recommend a potassium
supplement. Many people are not too concerned about
sodium
levels, but if for some reason you are, the food data tables (see below) do
include sodium information.
Commercial Non-TherapeuticFood: Ingredients and Quality
Many people who write to me do not like the idea of
feeding a therapeutic kidney diet, and the most common reason for their
reluctance is that they do not like the ingredients in these foods, often
considering them to be poor quality compared to the foods they usually feed.
This is not the place for me to start a big debate about
the best ingredients for cats, which could easily turn into a novel. But
just as I mention above that you did not cause your cat's CKD
because of the foods you chose to feed, it is equally true that whichever foods you
did choose
did not prevent your cat developing CKD. CKD is just not that simple.
explains more about the
guidelines of AAFPO (Association of American Feed Control Officials). Note
that the amounts given here are minimums.
Premium, Natural and Human Grade Foods
As with any lucrative market, there is a lot of marketing
and hype about quality cat foods. Let's take a brief look at some of those
catchy marketing claims.
People often assume that
I feed so-called premium foods. However, I
am not a fan of most premium foods:
they often contain fruits and vegetables including
cranberries, inappropriate for CKD cats,
and in my opinion are unnecessarily complicated
foods.
Many of these foods
seem to me to be designed to appeal to the humans buying them, not to
the cat.
The Association of American Feed Controls Officials
has stated "Because cats and dogs do not
select their own foods, and their human ownersdo, it is not rare at all that labeling and marketing information isdesigned to appeal to the latest trend in marketing human products."
Cats have very little need for fruits and
vegetables - normally they would only eat the small amounts contained in a
mouse's stomach, and even those would be pre-digested by
the mouse - so I do not see the attraction of all those carrots,
sweet potatoes and blueberries for my cats.
Some of these foods are also
acidified — many commercial foods are, unfortunately, but again this is
not suitable for a CKD cat.
(2015) LM
Freeman NAVC/WVC Symposia Proceedings says "Pets require nutrients,
not ingredients. A food full of great-sounding ingredients can be less
nutritious than one containing less appealing (to people) ingredients. Some
manufacturers may add ingredients to products solely for marketing purposes,
to increase the appeal of the food to consumers. These ingredients may have
unproven benefits, be present in miniscule amounts, and provide nothing to
the food but added expense. More ingredients also mean increased quality
control measures (and more time and expense) are necessary to ensure that
the finished product adheres to the desired nutrient formulation."
If you do decide to feed
this type of food (and I know some cats do enjoy them) and you are in the
USA, check the
food data tables
to find those with the
lowest phosphorus levels. If you can't
afford such foods, don't worry, because some relatively cheap foods are not
as poor in quality as you might have been led to believe.
(2014) Buff PR, Carter RA, Bauer JE & Kersey JH Journal of Animal
Science92(9) pp3781-3791 says "The term "natural," when used to market commercial pet foods
or pet food ingredients in the United States, has been defined by the
Association of American Feed Control Officials and requires, at minimum,
that the pet food be preserved with natural preservatives. However, pet
owners may consider natural as something different than the regulatory
definition."
has also stated "in
an effort to appeal to customers, marketers have increasingly used the term
on pet food product labeling", and says "Natural
is a liberal term that includes more ingredients than it excludes—most pet
food ingredients are derived from “plant, animal or mined sources." A feed ingredient
can be subject to a number of commonly-used processes during the
manufacturing process and still be deemed natural."
Human Grade Foods
Some people tell me they have always fed human grade
foods and are concerned that therapeutic kidney diets are not of this
quality.
Can we eat it?
(2009) Lau E Veterinary Information Network
quotes the chair of the
Association of American Feed Control Officials’ Pet Food Committee as
sayingthat
human grade food "is essentially a made-up term used by marketing interests
to describe and promote products in light of anthropomorphic responses
people have to their pets.”
says "There
have been “human-grade” claims on some pet foods for a few years. This term
has no definition in any animal feed regulations. Extremely few pet food
products could be considered officially human edible or human-grade. A pet
food that actually met these standards would be expensive. While pet owners
can buy what they feel is best for their pet, they should understand the
definitions and the odds."
Please also read the section above about
high quality protein
from a CKD perspective.
Grain-Free Foods
I know some people dislike feeding food with grains, and
try to avoid ingredients such as corn.
Whilst this may be necessary for medical reasons, e.g. cats with food
allergies or IBD), it may not be the best choice for other cats. This is
because, according to
FDA investigation into potential link between certain
diets and canine dilated cardiomyopathy
(2019) US Food & Drug Administration states, there have been recent reports
of dogs fed grain-free diets developing dilated cardiomyopathy, a heart
condition that can be difficult to treat.
It's not just grain-free: an update on diet-associated
dilated cardiomyopathy
(2018) Freeman LM Cummings Veterinary Medicine Center at Tufts University
explains more about this. As far
as I know, no cats have been diagnosed with a similar problem.
One grain where I have few concerns
is corn gluten meal. Corn gluten meal is actually the protein part of corn.
As obligate carnivores, cats require a particular mix of amino acids, and
corn gluten meal contains all of the ones that cats need (it may
be a little low in lysine).
Evaluation of meat meal, chicken meal, and corn gluten
meal as dietary sources of protein in dry cat food
(2005) Funaka M, Oka Y, Kobayashi S, Kaneko M & Yamamoto H, Namikawa
K, Iriki T, Hatano Y & Abe M The Canadian Journal of Veterinary Research69 pp299-304 found that corn gluten meal is almost as
bioavailable as chicken meal.
I would not choose a food that had corn gluten meal as
its first ingredient but if it is further down the ingredient list, it would
not be a concern to me.
By-Products and Poor Quality Ingredients
Many people are reluctant to feed by-products, fearing
they are not good quality ingredients.
AAFCO
defines
meat by-products as "the
non-rendered, clean parts, other than meat, derived from slaughtered
mammals. It includes, but is not limited to, lungs, spleen, kidneys, brain,
livers, blood, bone, partially de-fatted low temperature fatty tissue, and
stomachs and intestines freed of their contents. It does not include hair,
horns, teeth and hoofs. It shall be suitable for use in animal feed. If it
bears a name descriptive of its kind, it must correspond thereto.”
As you can see, by-products include the parts of an
animal which most of us humans would not choose to eat, but it must not be
forgotten that when cats catch their own prey, they usually eat the lot. If
I eat chicken, I prefer chicken breast, but my cats would happily eat
giblets. So the presence of by-products in a cat food does not automatically
put me off a food (for my cats; I live on chocolate).
Choosing a Food
So you have
ploughed through this page, and your head is spinning and you're now
thinking "please just tell me which food to feed!" I wish I could, but
sadly it's not that simple — I don't know your cat, his or her particular
needs and preferences or which foods are available where you live. But, assuming you
really, truly cannot persuade your cat to eat a therapeutic kidney diet, here are some
suggestions to get you started.
In order to make it easier for you to choose a food, I
have compiled food data tables showing the phosphorus, protein, sodium and
fat levels in many cat foods available in the USA,
including the therapeutic kidney diets and some other therapeutic diets, so you can make comparisons
of the components. Most of these foods are also
available in Canada.
It is not a case of looking at the
tables and simply buying the food nearest the top of the table that is
available to you locally. I am not recommending any of these foods. The tables simply list commercial cat foods in
order of phosphorus content. I am not recommending any of these foods.
How should you use the tables? The first thing to do is
to check if the food you have been feeding your cat is on the tables and if
so, how much phosphorus, protein etc. it contains. With any luck it will
be a food near the top of the table, in which case you can speak to your vet
about continuing to feed it.
If the food you are feeding is not on the table or is
lower down with a higher phosphorus content (remember, you want a food with
the phosphorus level as close to 0.5% as possible), you need to consider
alternative foods. Many members of Tanya's CKD Support Group go to their
local store and try to buy one can of various foods containing phosphorus
below 0.75%. They choose foods based on their cat's preferences for texture,
ingredients etc and also their own (no by-products etc). You can also contact manufacturers for samples
— some will mail
cans or vouchers to you. Then experiment to see which, if any, of these
foods appeal to your cat and feed the lowest phosphorus food you can. if
your cat gets bored with foods easily, maybe try
rotating two or more foods (i.e. feeding one food for a few days, then another,
or feeding one food in the mornings and another later in the day), though
remember frequent food changes may upset some cats' stomachs. Make sure
you keep notes so you remember which foods may work, because your cat will
probably go off whichever food you choose, at least for a while (you may be
able to re-introduce such foods later after a break).
With canned foods, a lot of cats seem
to like a pâté texture. Unfortunately many pâté foods are high in
phosphorus, but you could consider Hill's foods (which are
available in both the UK and the USA), because a lot of Hill's foods are
pâté texture and low in phosphorus, and many CKD cats seem to like them.
Many senior foods are relatively low in
phosphorus and protein, but they may also be lower in fat, which is not ideal for cats who are
already on the thin side, or for older cats who tend to have
poor fat digestibility.
in the USA (the nearest UK equivalent is Purina Gourmet Gold) is
often a big hit with cats but sadly it now has much higher phosphorus levels
than it used to, so would not be my first choice, though it is worth keeping
it in stock for times of crisis.
Foods which resemble human foods,
such as Weruva or Applaws, often seem to be popular with CKD cats, and many
of these are relatively low in phosphorus but they also tend to be
high in protein and low in fat and calories, so you should monitor your cat's
weight closely.
Always ensure the food you are feeding
is complete. Some of the Applaws foods, for example, are for supplementary
feeding only.
Personally I would not feed fish-based
foods exclusively. See
below for more on this.
It can be hard for cats who are used to receiving treats to find
that they are suddenly no longer given any. Some people like to use treats
to reward their cats, for example after sub-Qs.
If your cat normally eats canned food, you may find that
a couple of pieces of dry therapeutic kidney food are considered a treat by
your cat. Members of my support group have found Royal
Canin Veterinary Diet Renal Select RSE 24 good for this because it is
crunchy on the outside and soft on the inside. Hill's t/d (designed for
dental care) is also popular, and contains 0.79% phosphorus.
There are also one or two
kidney-friendly treats available. If your cat really prefers another treat,
since treats are only a small part of any diet, I personally would not worry about giving
a couple each day.
For information on diet for cats with
both diabetes and CKD, please see the
Diabetes
page.
Food Allergies or IBD
(Inflammatory Bowel Disease)
Generally speaking, you need to
control IBD over CKD, because it is academic what food you feed if your cat
can't keep it down or in. Fortunately there is a recent trend for manufacturers to
produce kidney-friendly hypoallergenic diets.
Trovet, a Dutch company, produces
Renal Venison RID
food in both canned and dry versions for those
in the UK or Europe, with phosphorus levels in the
0.50-0.65% range
If your cat cannot eat these foods for some reason, some
of the non-CKD limited
ingredient diets are at least relatively low in phosphorus. For example,
Hill's z/dand d/d
in the USA are low phosphorus foods.
Royal Canin HP Hypoallergenic dry food in the USA is
apparently also low phosphorus, but the canned version is not. See the food
data tables (canned) and (dry) for more information.
has
a video about the nutritional requirements of cats with food allergies.
Foods for Cats with Struvite Crystals (Feline
Lower Urinary Tract Disease)
These foods are acidified and are therefore not suitable
for most CKD cats (see
below).
Although it is very rare, a CKD cat may
occasionally have struvite crystals, in which case you may need to
feed an acidified food. However, many manufacturers now make foods that aim
to balance the urine pH rather than to acidify it, so one of these foods may
be a better choice for a CKD cat with struvite crystals. Discuss this with
your vet.
If your cat has calcium oxalate
crystals or stones, most therapeutic kidney diets are suitable for this
problem, see
Kidney
Stones.
Homemade Foods
Some people feed their cat a homemade diet, either raw or
cooked. Since cats have very complex nutritional needs, this is not
something which should be undertaken lightly; you need to do a lot of
research in order to ensure that you are providing correct levels of
essential nutrients.
Pet Diets
says "Unless properly formulated by a
nutritionist, diets made at home are not likely to be nutritionally complete
and balanced. The nutritional profile of any diet—including homemade
diets—depends on how the recipe was formulated, the nutrient content of the
ingredients, and how the owner prepares the diet."
Evaluation of recipes for home-prepared diets for dogs and cats with chronic
kidney disease
(2012) Larsen JA,
Parks EM, Heinze CR & Fascetti AJ Journal of the American Veterinary
Medical Association240(5) pp532-8 found that many of the recipes
analysed in the study would not meet nutritional needs.
It is particularly important to get the ratio of phosphorus to calcium
correct, and to ensure that you are providing enough
taurine— taurine deficiency can cause blindness and heart
failure. You also need to be
particularly careful with
raw diets
since these may increase the risk of
salmonella poisoning.
Evaluation of the nutritional adequacy of recipes for
home-prepared maintenance diets for cats
(2019) Wilson SA, Villaverde C, Fascetti AJ & Larsen JA Journal of the
American Veterinary Medical Association254 pp1172-1179 analysed
114 recipes for homemade food (some of which were provided by vets) from
books (66 foods) and online (48 foods) and compared them with the guidelines
issued by
Your cat's nutritional needs
(2006) National Research Council.
There was not enough information to properly analyse ten of the recipes.
None of the remaining recipes met all the NRC guidelines. Eight of them
contained potentially toxic ingredients such as
onion or garlic. More
than 50% of the recipes did not contain enough
taurine. and lacked other vital nutrients or exceeded the safe limit for
others. The study concludes "Problems with nutritional adequacy were
identified in all evaluated HPMD [home-produced maintenance diet] recipes.
Appropriate formulation of HPMDs requires specialized knowledge of nutrition
and use of computer software to avoid potentially harmful nutrient
deficiencies."
If you still want to look into making a homemade diet, here are
some sites with more information and recipes. Personally I would only want
to use a recipe prepared by a specialist veterinary nutritionist. Be careful about using a diet
with a high amount of carbohydrate since cats have no nutritional
requirement for large amounts of carbohydrate. It can
also be difficult to work out the fatty acid ratio in a homemade food. Please
check with your vet before using any of these
diets. Be aware that CKD cats, who often have poor
appetites, may not appreciate your culinary efforts.
(2010) Schenck P has recipes from a vet. Scroll down to Cat Recipe
Nutritional Breakdowns Renal, and click on http next to Cat Recipe
Nutritional Breakdowns Renal. An excel file will download with five
different recipes for CKD cats. Some people have expressed concern regarding
baking soda and calcium carbonate being interchangeable in the recipes. Dr
Schenck actually addresses this issue on herAmazon page.
Please note the comment about working with your vet.
is a
site run by veterinary nutritionists. It sells supplements which are
designed to be used in the free recipes which the site generates based on
your cat's particular nutritional needs, including one for kidney
disease, but it also offers free recipes
based on supplements (such as fish oils) available from health food stores.
The site provides a nutritional breakdown of the recipe you create on a
metabolisable energy basis.
in the
USA can devise a diet to suit your cat if your vet contacts them and
provides current bloodwork. The personalised diet cost around US$250 in 2015.
provides a recipe for Hill's
homemade CKD food. This
recipe was apparently originally provided by Hill's to vets to offer to
people whose cats would not eat a commercial diet. Other versions of this
recipe which I have seen also included two cups of rice.
is a supplement for homemade diets available from Zooplus which is
apparently phosphorus-free. I have no idea if it is the correct balance, so
please check before using.
(2006) National Research Council report that
"If given free access to food, cats will eat between 12 and 20 meals a day,
evenly spread out over the 24-hour light-dark cycle. It goes against the
nature of the cat to force it to eat only one meal a day."
(2005) Kirschvink N, Lhoest E, Leemans J. Delvaux F, Istasse L,
Gustin P, Diez M Journal of Veterinary Internal Medicine19
p476 found that cats fed more frequently increased their fluid intake.
Free feeding a CKD cat has an additional benefit, namely that
feeding little and often
may reduce the problem of excess stomach acid, a common problem in CKD cats.
Dry food tends to lend itself quite well to free feeding,
but canned food may be a better choice for CKD cats. If you are out a lot
and wish to free feed canned food, an automatic timed feeder is a good idea.
As desert animals, healthy cats do not drink a lot, but
instead they obtain moisture from their prey. A mouse, for example, is
around 60% water. Canned cat foods contain even more moisture than this,
between 75-85% in most cases, so a healthy cat who eats primarily canned
food will not drink much at all.
Issues with Dry Food
Most dry cat foods only contain 8-10% moisture, so cats
who eat dry food do tend to drink more than cats fed on wet food, but they
simply cannot take in as much moisture overall as a cat fed on wet food.
The carnivore connection to nutrition in cats
(2002) Zoran D
Journal of the American Veterinary Medical Association 221
pp1559-67, states "cats eating commercial dry foods will consume
approximately half the amount of water (in their diet and through drinking),
compared with cats eating canned foods...In older cats that tend to produce
urine with a lower concentration, an increase in water consumption becomes
even more important to avoid dehydration and development of
prerenal
azotaemia."
Whilst many healthy cats seem to manage fine with dry
foods, it may be preferable to give a CKD cat a wet food if possible so as
to reduce the possibility of dehydration. The cat food manufacturers produce
their therapeutic kidney diets in both dry and wet versions, but
I would try to feed your cat the wet versions if possible. However, if my
CKD cat would not eat wet CKD food but would eat the dry version, I would
feed that.
Johnson-Bennett P has tips on switching your cat from dry to canned food.
Issues with Canned Food
One study,
Epidemiologic study of relationships between consumption of commercial
canned food and risk of hyperthyroidism in cats
(2004) Edinboro CH, Scott-Moncrieff JC, Janovitz E, Thacker HL & Glickman LT
Journal of the American Veterinary Medical Association224 (6)
pp 879-886, indicates that cats who eat canned food, particularly from
pull-ring cans, appear to be at increased risk of developing
hyperthyroidism. It is thought that this may be related to the lining
used in these cans, bisphenol-A (BPA), a potential endocrine disrupter. It
is therefore probably worth trying to feed your cat food from foil pouches
or plastic trays rather than from cans. If you do use cans, be sure to store
any leftover food in glass containers in the fridge rather than in the tins
themselves.
The University of Warwick
has more
information on this.
(2011)
Wei A, Fascetti AJ, Villaverde C, Wong RK & Ramsey JJ American Journal of
Veterinary Research72(7) pp918-23 found that healthy cats fed a canned diet
ate more than cats fed the same diet in freeze-dried form, but took in less
energy and "had a significant decrease in body weight." This is
perhaps
because the amount of water in canned foods makes the cat feel full more
quickly.
Another possible issue with canned food is that some cats
find it harder to eat than dry food. Canned food does not allow cats to
get their teeth into it as with a mouse. They often have to lap canned food
up, almost as if it is liquid. Many cats do this with foods canned in gravy
— my Persians (one of whom was not particularly flat-faced) always seemed to
simply lick the gravy and leave the chunks. Again, this may lead to a lower
calorie intake overall. and in severe cases, the cat may go hungry. For this
reason I usually feed pâté-style canned food, and as my cats eat and spread
the food all over the bowl, I put it back into little piles at intervals.
For a CKD cat, a possible compromise,
especially with dry food junkies, is to feed them both dry and canned
therapeutic kidney diets. Some people do this by feeding a dry therapeutic
kidney diet
while they are out at work all day, but they then feed the canned food when they are home.
(2008) Buffington CAB Canadian Veterinary
Journal49 p561-3 states that there is little evidence that dry
food contributes to diabetes or ill health generally in cats.
(2010)
state (page 48) "Both canned and dry food have been found to support
health during all life stages.
The panel examined published peer-reviewed evidence-based studies in
healthy, client-owned cats for any significant health effect of: feeding
canned versus dry food (including contribution to dental health); providing
a variety of foods versus a consistent diet; feeding high protein, low
carbohydrate versus lower calorie and high fiber diets; feeding raw diets;
providing dietary supplements, or access to grass or plants. Based on the
available data, specific recommendations in favor of any of these practices
cannot be made."
With CKD cats, obviously you wish to avoid dehydration as
much as possible, but the most important thing is to keep them eating. If
your cat is a dry food junkie, and is prepared to eat a dry therapeutic
kidney food,
I would feed it. You can always add water to the dry food to
make it less dry, though if you do this, you should not leave the food down
for too long because it will spoil. An alternative would be to switch to
semi-moist renal food in pouches.
Food Cautions
The following are not recommended for your CKD cat:
You should never feed anything containing onions to any
cat. Onions contain an alkaloid disulfide compound which can damage red
blood cells and cause a cat
to develop a serious form of anaemia called Heinz body anaemia. This can kill,
and particularly susceptible cats may only need to eat a tiny amount of
onion for this to happen, although symptoms may take several days to appear.
Since garlic is a member of the same family (allium), some people believe the same caution applies to garlic.
Sixteen cases of allium poisoning in cats were dealt
with by The Veterinary Poisons Information Service (VPIS) in the UK, which
is part of the Medical Toxicology Unit at Guy's and St Thomas'Hospital in London. Follow up details were
only available for four of these cats. One died, two recovered. As for the
fourth, "anaemia and jaundice were ongoing problems at the time of follow up
after a cat had eaten garliccloves."
(2011) Salgado BS, Monteiro LN
& Rocha NS Journal of Venomous Animals and Toxins including Tropical
Diseases17(1) pp4-11 found that all allium species can be toxic
to cats and dogs but that cats are 2-3 more times susceptible to damage than
other species. It states that poisoning can
occur if a 10lb cat eats 10oz (250g) of onion and that it can still be
dangerous even if the cat eats smaller amounts over several days.
(2005) Cope RB Veterinary Medicine100 (8) pp562-566 mentions
that onions, garlic, leeks and chives are potentially toxic to dogs and
cats, and that problems may occur after consumption of a single large
quantity or repeated consumption of small amounts, even of dietary
supplements rather than garlic or onion themselves.
(2006) National Research Council
in the USA
provides a summary of the findings from the Committee on Examining the
Safety of Dietary Supplements for Horses, Dogs and Cats (2008) and
states that the committee was unable to determine a presumed safe intake
level of garlic for cats.
is a site owned by Dr Rebecca
Remillard, a veterinary nutritionist, which states "the possibility of
developing a Heinz body hemolytic anemia appears to be variable between
pets, and it is not possible to predict which animals may or may not have
such a reaction to onion or garlic." Search for garlic, and it is
in the answer to the last question on page 3 (Is it OK to give
my pet a garlic pill once a week?)
(2000)
Lee KW,
Yamato O,
Tajima M,
Kuraoka M,
Omae S
&
Maede YAmerican Journal of Veterinary Research61(11) pp1446-50
found that HCT levels reduced in dogs fed garlic extract, and Heinz bodies
were detected. The conclusion was that
"foods containing garlic should not be fed to dogs." Cats are even more
sensitive to Heinz body anaemia than dogs, so this advice applies even more
so to cats.
Foods for Urinary Tract Health
People often assume that foods which
state that they are designed to "support
urinary tract health", or "magnesium-controlled",
or words to that effect are intended for CKD cats, but
this is not the case.
This type of food is acidified because it is designed to treat a different kind of problem
called
FLUTD (Feline
Lower Urinary Tract Disease), where the cat's urine is too alkaline
(sometimes referred to as struvite crystals). These foods are not intended for CKD cats
at all, because
CKD cats tend to have quite high acid levels anyway.
Acidified foods may
also have the effect of increasing the amounts of potassium lost in
the urine, which is bad for most CKD cats.
You should also avoid foods that contain
cranberries
or additional
vitamin Cfor similar reasons.
If your cat has both CKD and struvite crystals,
click
here.
Raw Food
I sometimes hear from people who think
a raw food diet will solve all their CKD cat's problems. I wish it were that
simple! I'm not opposed to raw diets per se, I considered feeding one myself
during the 2007 pet food recall scandal. But feeding raw is not a magic cure
for CKD, and there are possible problems:
Firstly, it can be hard to create a
proper balanced diet. It's not just a
case of plonking a piece of raw chicken on a plate and thinking you've
cracked it. You need the correct balance of nutrients, and it isn't easy.
Please see
homemade foods
for more information.
Secondly, it
can be hard to know the protein and phosphorus content of the food you are
feeding. The
USDA National Nutrient Database
may help
with this — it is a
database where you can search for any food ingredient and get a nutritional
breakdown, including phosphorus and protein levels.
The main concern for CKD cats is the
risk of infection, because
CKD cats are immune-compromised, so
are more at risk of infection.
(2017) Giacometti F, Magarotto J, Serraino
A & Piva S
BMC Veterinary Research13(1) p224 reports on two cats from the same
household suspected of having salmonella (which was found in their faeces)
after being fed a homemade raw diet. It concludes "RMBD should be fed to
pets with caution as they could lead to infection, especially in animals
with impaired host immune defences."
(2017) Hamper BA, Bartges JW & Kirk CA
Journal of Feline Medicine and Surgery19(4) pp424-434 compared the
feeding of two raw foods and commercial canned food to healthy
kittens. It found that all of the diets supported feline growth, but that "Salmonella
serovar Heidelberg and C difficile enterotoxin were detected in the
feces of some of the raw feeders, substantiating pathogen exposure and risks
to both animal and owner."
(2006) Weese JS & Rousseau J Canadian Veterinary
Journal47(9) pp887–889 found that salmonella
could persist in bowls used to hold raw meat despite thorough cleaning. The
study states that this was surprising, "particularly their survival
following soaking in bleach and washing in a dishwasher at 85°C. Bleach is
typically a highly effective disinfectant that would be expected to kill
Salmonella spp. However, bleach is less effective in the presence of organic
debris, so possibly the small amount of food residue in the bowl was enough
to permit survival of the Salmonella sp. in some cases. This likely accounts
for the finding that only scrubbing followed by soaking in bleach was
effective at reducing the Salmonella sp. contamination. However, even this
method of disinfection did not completely eliminate Salmonella bacteria in
all bowls."
The incidence of salmonella
in cats generally is very low, but
immune-compromised CKD cats may be at greater risk. Salmonella
is a very nasty disease which could push a CKD cat over the edge. At the very least
it will probably take a CKD cat longer to recover from it than a healthy cat.
(2005) is a report by the Journal of the American Veterinary
Medical Association which found that 99% of raw meat samples intended for
dogs were contaminated with a variety of bacteria. Some people believe that
freezing the food before feeding kills pathogens but the
New Zealand Food Safety Authority
explains that this is not necessarily the case.
(2019) O’Halloran C, Ioannidi O, Reed N, Murtagh K, Dettemering E,
Van Poucke S, Gale J, Vickers J, Burr P, Gascoyne-Binzi D, Howe R,
Dobromylskyj M, Mitchell J, Hope J & Gunn-Moore D
Journal of Feline Medicine and Surgery21(8) pp667-681
reports on an outbreak of TB in cats in the UK. Five of the six cats showing
symptoms died, and another seven cats living in the same households were
also found to have TB. In one case, the cat's caregiver also had to be
treated for TB. All of the cats were fed Natural Instinct wild venison food
and the study states "the only probable source of infection is that the cats
were all exposed to M bovis via the same commercially available raw food."
(2013) Freeman LM, Chandler
ML, Hamper BA & Weeth LP Journal of the American Veterinary Medical
Association243(11) pp1549-1558 discusses the pros and cons of
raw meat-based diets, and mentions that a study of dogs found that dogs fed
a raw diet had significantly higher BUN, creatinine and HCT levels than dogs
not fed such a diet.
(2020) Summers SC, Stockman J, Larsen JA,
Zhang L & Rodriguez AS Journal of Veterinary Internal Medicine34(1)
pp 266-273 states
"Of the 82 study foods, 7 foods (9%) contained concentrations of total P
[phosphorus]
(≥4.8 g/1000 kcal) that previously were demonstrated to cause a rapid
decline in renal health in adult cats when most of the P was provided by
inorganic P sources.
Of these 7 foods with total P ≥4.8 g/1000 kcal ME, most (4/7; 57%) were raw
foods, which is possibly attributable to these foods being high in protein
and possibly bone derivatives, the main source of organic P in pet food."
Although I often hear people extolling the apparent
benefits or raw, there is no research that I am aware of into the
superiority or otherwise of raw diets for cats, and certainly not for CKD
cats.
In
Advising clients who feed raw diets to pets
(2005) NAVC Clinician's Brief, Dr R Remillard, a veterinary
nutritionist, says "No scientific
evidence exists that a raw diet is superior to any dry or canned pet food.
As a result, this practice is associated with health risks to pet and family
with no demonstrable benefit." Ten years later, nothing had changed.
Pet food myth busters: answering common questions
owners ask about pet food
(2015) LM
Freeman NAVC/WVC Symposia Proceedings says "Despite anecdotal reports
from pet owners and even some veterinarians, there is currently no evidence
that raw foods offer any benefits over cooked ones. There is substantial
evidence, however, that raw foods may be associated with nutritional
deficiencies, bacterial and parasitic infections, and other health concerns
in pets. These foods also pose potential risk to people-especially those
that are immuno-compromised, such as young children, the elderly, and
patients receiving immune-modifying drugs or who have cancer."
advises against
feeding raw. If you already feed a raw diet which
your cat enjoys and with which you have had no problems, please do discuss
whether to continue with your vet. If you have not
previously fed raw, I would not recommend starting it because of the
possible risks of infection and because it can be quite a change for an
already sick cat. There are a few commercially available raw foods which are
pasteurised.
Fish is not an ideal food for
cats for
a number of reasons:
Steatitis
If you feed a cat a fish diet exclusively, the
cat can develop a condition called steatitis (yellow fat disease), which
is caused by a vitamin E deficiency resulting from the imbalanced diet.
Firstly the cat becomes very nervous, and then becomes hypersensitive in
all the nerve endings of its skin, so it is very painful for the cat to be
touched.
The treatment is usually massive doses of vitamin E under a vet's
supervision, and discontinuing any food containing vegetable oil or
mineral oil because this will deplete the body's stores of vitamin E even
more.
states that "like meat, it is deficient in calcium with an inverse calcium:phosphorus
ratio. Coley (or Saithe) a popular fish with cat owners in the UK and the
fillet cut contains 15-20 mg calcium per 100g but over 200 mg phosphorus
per 100g, a Ca:P ratio of 1:10. Cod and other white fish are similar."
Hyperthyroidism
One study,
Evaluation of dietary and environmental risk factors
for hyperthyroidism in cats(2000)
Martin KM, Rossing MA,
Ryland LM,
DiGiacomo RF, Freitag WA
Journal of the American Veterinary Medical Association217(6)
pp853-856, found that "cats that preferred fish or liver and giblets
flavors of canned cat food had an increased risk"
of
developing
hyperthyroidism. This may be because of the iodine content in the
food.
Domoic Acid
Domoic acid is a neurotoxin found in shellfish which can cause permanent
neurological damage sometimes referred to as amnesic shellfish poisoning.
There are strict regulations on the levels of domoic acid permitted in
shellfish for human consumption for this reason.
Domoic acid is excreted primarily via the kidneys, so researchers wanted
to examine its effects on the kidneys.
Characterization of renal toxicity in mice
administered the marine toxin domoic acid
(2014)
Funk JA, Janech MG, Dillon JC, Bissler JJ, Siroky BJ & Bell PD Journal
of the American Society of Nephrology 25(6) pp1187-97 found
that domoic acid may damage kidneys at levels one hundred times lower than
those which cause neurological problems. This research was performed in
mice who were given domoic acid directly rather than in shellfish, and
earlier studies indicate that this is more likely to cause problems.
Further tests are necessary to understand the implications for humans and
cats, but in the meantime, it might be wise to avoid feeding shellfish to
your CKD cat.
(2017) Davies M, Alborough R, Jones L, Davis C, Williams C &
Gardner DS Scientific Reports7 17107 found that some
fish-based foods sold in the UK contained high levels of arsenic. The
study states "some foods, particularly those with fish, were relatively
high in the metalloid, arsenic. Further examination revealed that only
those foods that declared incorporation of higher levels of fish
derivatives, as oppose to fish oil, had high levels of arsenic with three
being above a safe upper limit (SUL) for organic As, two above the legal
limit for food stuffs. Indeed, As levels tended to increase steeply when
≥30–40% fish was declared." The study goes on to say "Arsenic is water
soluble and accumulates in organs such as the liver and kidney, where it
is relatively toxic either by itself or via interactions with other
catalytic metals such as iron and copper. High urinary arsenic is
associated with increased risk of CKD."
There appeared to be a degree of correlation between high levels of
arsenic and high levels of mercury (see below).
Additional Risks for Tuna
Addictive Behaviour
Firstly, tuna
can be a very addictive food for some cats, to the extent that they will
refuse to eat anything else. Since tuna is not a balanced diet for cats,
this can be a problem.
Neurologic Disturbances
Commercial cat
foods formulated from tuna may be balanced, but The Merck Veterinary
Manual has said
"there are reports of
commercial cat food causing severe neurologic disturbances in cats fed an
exclusive tuna diet for 7-11 months."
advises pregnant women not to eat tuna. The
US Environmental Working
Group,
which worked on
the studies with the FDA, believes that
human-grade tuna has
unusually high levels of the toxic metal methylmercury.
It recommends
that pregnant women should not eat tuna at
all, and that children should eat tuna no more often than once a week.
Human-grade tuna tends to consist of the white "meat", while animal-grade
tuna tends to consist of the lower grade red "meat", so, at least in
theory, animal-grade tuna could contain more pollutants.
A 2003 study in The Lancet indicated that eating tuna may not be a problem
for pregnant women and children after all
(Web
MD
has a report on this), but I think it might be wiser
to err on the side of caution with a sick CKD cat.A
tuna fish diet influences cat behavior
(1988) Houpt KA, Essick LA, Shaw EB, Alo DK, Gilmartin JE,
Gutenmann WH, Littman CB, Lisk DJ Journal of Toxicolology &
Environmental Health24(2) pp161-72 found that "Cats fed the
tuna had elevated tissue levels of mercury and selenium."
What is in commercial cat and dog food? The case for
mercury and ingredient testing
(2019) Dunham-Cheatham SM , Klingler K, Peacock M , Teglas MB & Gustin MS
The Science of the Total Environment 684 pp276-280 found
mercury in 16 of the first 100 cat food samples they examined. Most of
these foods were tuna, as you might expect, but mercury was also found in
some foods containing other types of fish.
Thiamine (Vitamin B1) Deficiency
You might
decide to feed human grade tuna instead, but that does not avoid another
problem associated with tuna, namely
vitamin B1
(thiamine)
deficiency. Cats who eat tuna regularly can develop this
problem. Symptoms are often neurological and include the inability to
hold up the head (ventroflexion), dilation of the
pupils, loss of balance, seizures and death if left untreated.
Pet Place
has some information about this.
Provet
has information on this and on the dangers of feeding fish
to cats generally.
(2017) Steele MS VCA Animal Specialty Group discusses the case
of a cat who developed neurological problems linked to a thiamine deficiency
caused by a fish-based diet.
As you can see, feeding fish
regularly has some serious health implications for cats. A little
fish occasionally is unlikely to be cause for
concern, and feeding it for a few days during a time of
crisis should not be a problem (in fact, if you're in the UK, I find feeding
a bit of fish from the chippy - batter removed - can help with poor appetite
in many cats), but I would not recommend feeding it for any length of
time or too often, especially tuna.
Commercial Fish-Based
Foods
Please also read the section immediately above about
fish and tuna.
I tend to divide fish-based commercial foods into two
camps:
the "old school type", which are often mixed with other
ingredients (e.g. Chicken & Tuna) and which look like, well, catfood; and
the newer type foods which often contain fish only. These
are often advertised as "natural ingredients" and "high quality" and tend to
look like something that would be served to humans in a fancy restaurant.
These newer style foods are becoming increasingly popular
with manufacturers, but in most cases they are actually manufactured in
Thailand, which seems to be doing an amazing job marketing these foods.
Brand names include Weruva, Soulistic, Best Feline Friend and Tiki Cat in
the USA, and Schesir, Almo Nature and Cosma in Europe. Many manufacturers
are introducing some of this style of food as part of their general range
e.g. some of the Fancy Feast Elegant Medley foods.
Most commercial cat foods based on
fish are usually complete because they do not only contain fish, and are
formulated with additional ingredients such as taurine and Vitamin E to
prevent steatitis and taurine deficiency.
However, you do need to check the can closely because some commercial
fish-based foods are not complete foods e.g. some Applaws foods in the UK.
Unfortunately, the newer type foods
which only contain fish tend to be extremely low in both fat and calories,
so you may find that your cat either needs to eat several cans a day (very
expensive) or loses weight on such a food.
Personally speaking, I don't think I
would choose to feed commercial fish-based foods exclusively. I also would
not feed tuna-based ones longer-term exclusively — The
Merck Veterinary Manual states that
"there are reports of
commercial cat food causing severe neurologic disturbances in cats fed an
exclusive tuna diet for 7-11 months."
However, most cats do seem to love the newer style fish-based foods in
particular, so they may be helpful at times when your cat's appetite is poor
— you can add a little to your cat's regular food to encourage him/her to
eat.
One possible compromise is to add the water in which tuna
is packed to your cat's veterinary or other diet in order to make it more
palatable. See
tuna
water for more information.
Cat Food Recalls
Cat food recalls are frighteningly common. In 2007 quite
a few cats either died or suffered permanent kidney injury because of cat
food contamination (see
2007 Cat Food Recall).
In the UK in 2021 there were a number of cases of
pancytopenia, a serious condition which damages blood cells. A number of
brands, including Sainsburys and Applaws, have had some of their foods
recalled, although a causative link has not yet been established.
The Food Standards Agency
has a list of recalled foods.
The Royal Veterinary College
has an update dated August 2021 stating that they have treated 563
cats, of whom 63% have died.
TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE
EXTREMELY DANGEROUS.
I have
tried very hard to ensure that the information provided in this website is
accurate, but I am NOT a vet, just an ordinary person who has lived
through CKD with three cats. This website is for educational purposes
only, and is not intended to be used to diagnose or treat any cat. Before
trying any of the treatments described herein, you MUST consult a
qualified veterinarian and obtain professional advice on the correct
regimen for your cat and his or her particular requirements; and you
should only use any treatments described here with the full knowledge and
approval of your vet. No responsibility can be accepted.
If your cat
appears to be in pain or distress, do not waste time on the internet,
contact your vet immediately.
This site was
created using Microsoft software, and therefore it is best viewed in
Internet Explorer. I know it doesn't always display too well in other
browsers, but I'm not an IT expert so I'm afraid I don't know how to
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is on making the information available. When I get time, I'll try to
improve how it displays in other browsers.
This site is a labour of love, from which I do not make
a penny. Please do not steal from me by taking credit for my work.
If you wish to
link to this site, please feel free to do so. Please make it clear that
this is a link and not your own work. I would appreciate being informed of
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