In many ways,
this page is not particularly important, because in most cases it does
not matter how a cat developed CKD - the treatment is the same once it is
present (although in the case of
there may be other things which can be tried).
However, I am including the
information because so many people seem to blame themselves for their
cat's illness, when in truth CKD is rarely avoidable - as the
Happens in CKD page mentions, around 10% of cats over the age of ten will
develop CKD, with as many as 30% of cats over the age of 15 having the
This page is
divided into known causes of CKD and possible causes.
The possible causes
section is just that at this point, possible causes. This section
is not there to make you feel guilty about, say, your food choices. There is no
hard evidence that any of these possibilities truly do cause CKD, although
the anecdotal evidence is stronger for some than for others.
This is the
most commonly seen type of kidney problem, so when a vet says a cat has
CKD, s/he often means chronic interstitial nephritis. Cats with chronic
interstitial nephritis have small, shrivelled kidneys with scar tissue.
Happens in CKD page
explains why this occurs.
As humans age,
they are prone to developing cancer or heart disease; whereas cats are
more likely to develop kidney disease. It may be caused by any of the
other problems described in this section.
Feline morbillivirus, a previously undescribed
paramyxovirus associated with tubulointerstitial nephritis in domestic cats
(2012) Woo PC, Lau SK, Wong BH, Fan RY, Wong AY, Zhang AJ, Wu Y, Choi GK,
Li KS, Hui J, Wang M, Zheng BJ, Chan KH & Yuen KY Proceedings of the
National Academy of Sciences of the United States of America
109(14) pp5435-40 found that a recently discovered virus may also be
present in some cases of interstitial nephritis in cats.
Yahoo! News reports further on this
many cases interstitial nephritis is basically "old age" kidney disease
wherein the kidneys simply "wear out." In other words, it is nothing to do
with anything you did or how you cared for your cat, so no guilt trips
Polycystic Kidney Disease,
or PKD, is a condition in which cysts form on the kidneys. There is
detailed information about PKD on the
Polycystic Kidney Disease
conditions, the kidneys either do not develop normally (renal
dysplasia) or they do not develop completely (renal hypoplasia). In some
cases of renal hypoplasia, known as renal aplasia, the cat has only one kidney.
Cats with only one kidney tend to be male, and for some reason it is
usually the right kidney which is missing.
Cats who develop
CKD at an early age often suffer from renal dysplasia or renal hypoplasia.
These cats often are rather small, and may be
noticeably smaller than their littermates.
This is a rare
condition in which the kidneys are damaged by urine flowing backwards into
the kidney. A genetic form of this has recently been identified in
Ragdolls, and research is underway at the University of Helsinki in
is a bacterial infection of the kidneys. The cat may also have a lower
urinary tract infection - in some cases, untreated lower urinary
tract infections rise into the kidneys - but not always. Cats with
Polycystic Kidney Disease
particularly prone to pyelonephritis, since the bacteria can burrow into
the cysts. Our PKD cat, Harpsie, used to get regular bouts of pyelonephritis.
If your cat has a kidney infection
and also has high bloodwork values, the bloodwork may
improve once the infection is under control.
infectious peritonitis is a serious and often fatal condition that
develops in some cats who catch the corona virus. FIP is notoriously
difficult to diagnose, and testing positive for the corona virus does not
inevitably mean that the cat will develop FIP.
FIP occurs in
two forms, effusive (wet) and non-effusive (dry). Cats with the non-effusive form of FIP
sometimes have enlarged kidneys and kidney problems. However, very few
cats on Tanya's Feline CRF Support Group have FIP.
Dr Diane Addie
is a lecturer in veterinary virology, and is an expert on FIP. Her site is
available in a number of different languages.
are very fine blood vessels in the kidneys that act as filters of waste
products to produce urine. If they are damaged, blood proteins, which
would normally be recycled into the bloodstream, may leak out into the
urine (proteinuria). In severe cases, the resulting low levels of protein
in the blood may cause weight loss and a build-up of fluids under the skin
disease is an immune-mediated disease, and is not as common as
interstitial disease. It is actually relatively rare in cats, and is
usually secondary to some other condition such as an infection,
inflammatory disease or diabetes. Glomerulonephritis is often managed
differently to CKD - using medications to
suppress the immune system may help, and one study found that
amino acids may help.
ACE inhibitors may also be of use for
this condition because they appear to reduce the proteinuria commonly see
in patients with glomerulonephritis.
E Cure Me is a human site with
information about nephrotic syndrome.
It appears that
dental problems may be linked to an increased risk of other health issues.
Although the precise mechanism is not known, scientists believe that in
humans there may be a link between the oral bacteria associated with poor
dental hygiene and heart disease.
The National Institute of Dental and Craniofacial
Research reports on studies to date.
A similar link
is thought to exist in cats.
The American Animal Hospital Association
states that "Dental disease doesn’t affect just the mouth. It can
lead to more serious health problems including heart, lung and kidney
For many years it was thought that hypertension in cats was the result of
another condition, such as CKD or hyperthyroidism. Whilst it is true that
hypertension is more common in cats with these conditions, it is gradually
becoming clear that primary hypertension does exist in cats, and may in
fact contribute to the development of CKD. There is more information on
the Hypertension page.
Feline hypertension: risks and management
(2005) is a presentation by Dr Clarke Atkins to the World Small
Animal Veterinary Association Thirtieth World Congress, in which he states
"adding to the confusion in
understanding the pathogenesis of hypertensive renal disease, renal
disease begets hypertension and hypertension begets renal disease."
(kidney stones) may cause kidney problems. The stones may calcify, and cause
damage that way, or they may lodge in the ureter, thus allowing waste
products that would normally be excreted by the bladder to build up in the
kidneys - this is called obstructive nephropathy. If a cat's
suddenly becomes extremely high, a kidney stone blocking the ureter may be
the cause. The diagnosis can usually be confirmed via
ultrasound. The ultrasound may show one small kidney and one enlarged kidney (see
There is more
information about kidney stones on the
Kidney Stones page.
(lymphosarcoma) is a type of cancer in which white
blood cells called lymphocytes become cancerous and produce tumours.
Around 50% of cats with lymphoma also have feline leukaemia.
Lymphoma may be
found in several parts of the body; if it occurs in the kidneys, it is
called renal lymphoma. It is the most common type of renal cancer in cats. As renal lymphoma progresses, it may cause
Some of the
symptoms of renal lymphoma resemble those of CKD. For example,
BUN may be
elevated because of internal bleeding (which may eventually also cause
anaemia). Renal lymphoma
may cause the kidneys to become enlarged (see
but this is not always visible on x-ray because it is a soft tissue type tumour,
though it may show on
can often be treated with
steroids and occasionally chemotherapy, and in many cases it has a good
prognosis. Cats tend to cope far better with chemotherapy than humans do,
so I would consider this treatment if you are offered it.
Renal diseases in cats (2002) is a
presentation by JP Pagès to the 27th World Small Animal Veterinary
Association Congress. Section 2.5 discusses renal cancer.
nephrotoxins include lilies and antifreeze, which cats may lick or eat
accidentally (the taste of antifreeze is unfortunately very attractive to
cats). In most cases these cause
Injury, but in some cases, if the cat recovers, there may
be residual kidney damage resulting in CKD.
Non-steroidal anti-inflammatory drugs are very effective at controlling
pain and inflammation in cats, but unfortunately cats cannot metabolise
them very well. Meloxicam
is an NSAID available in both injectible and liquid
(oral) form. Although it is approved in the UK for the ongoing
treatment of arthritis in cats (and I myself used it successfully for my
not CKD cat who had severe arthritis), there are concerns that it may
cause kidney problems
in some cats,
particularly when used at higher doses, as tends to happen in the USA
where cat-sized formulations are not available.
read more about meloxicam and other NSAIDs in
Treatments section, which includes a protocol for what to do if your
cat experiences an adverse reaction.
Amyloid is a
type of protein found in the body. In amyloidosis, amyloid is deposited in
organs and tissues where it does not belong, so it adversely affects them. In cats, the deposits
are often found in the kidneys, and they eventually lead to CKD. Amyloidosis is not particularly common, but it may be found in Abyssinian
cats in particular, and sometimes in Siamese and Oriental cats. Cats with
amyloidosis often have
Perinephric or perirenal pseudocysts are large fluid-filled sacs that form around one
or both of a cat's kidneys. They appear to be more common in male cats,
and the cat may appear healthy apart from having an abdomen that is
increasing in size but not usually tender to the touch. Upon examination,
which is usually performed via
ultrasound, the kidneys are usually
The cysts may be treated by draining the fluid, but this is often only a
temporary measure. Removing the wall of the cyst may be more effective,
but in more severe cases it may be necessary to remove a kidney. However,
this is a last resort because it may
lead to CKD, since many cats with these cysts tend to have
compromised kidneys (they are often already in early stage CKD) and/or urinary tract infections. However, the first
link below does state that the prognosis is usually good if accompanying
CKD is not severe and no other diseases are present.
These are just
that - areas where people have their suspicions, but there is no real
evidence that these are causes of CKD, although the evidence for some is stronger than for others. Further research is
needed, and in some cases is ongoing.
The connection arises because feline vaccines are grown
on kidney cells known as Crandell Reese Feline Kidney (CRFK) cells. It has
long been known that growing the vaccines in this way produces some
unidentified antibodies in addition to those required for the vaccine, but
it has only recently been discovered that the unidentified antibodies were
to renal tissue. These additional antibodies occur in all modified live or killed vaccines,
but do not occur with intranasal vaccines. In the UK, live vaccines are
Interstitial nephritis in cats inoculated with
Crandell Rees feline kidney cell lysates (2006) Lappin MR,
Basaraba RJ, Jensen WA Journal of Feline Medicine and Surgery
8(5) pp353-6, found that 50% of the cats in the study who were given
normal vaccines developed
nephritis according to biopsies. However, these cats were
vaccinated 12 times in 50 weeks, which is obviously far more often than is
normal (the current US guidelines are for cats to be vaccinated only once
every three years). One group of cats in the study were given intranasal
vaccines, and they did not develop any signs of interstitial nephritis.
Feline vaccine side effects (2012) is a
presentation by Dr Lappin to the 84th Western Veterinary Conference,
in which he states that in his research cats who developed antibodies did
not go on to develop CKD. He recommends that core vaccines should continue
to be given to healthy cats in accordance with the
American Association of Feline Practitioners
these findings, I
would not recommend giving any vaccines to a cat who already has CKD:
vaccines are intended for healthy cats and a CKD cat is not healthy. Once
Thomas had been diagnosed, our vet felt it was not wise to give him his
usual vaccinations, and we agreed with her. For healthy cats,
intranasal vaccines appear to be safer. Please see the
Treatments page for more information on the use of vaccines in
cats, and discuss what is appropriate for your own cat with your vet.
Chronic renal failure in cats Dr D Chew
mentions that low potassium levels (hypokalaemia) "can both
initiate and perpetuate chronic renal damage." One study,
Chronic renal disease and potassium depletion in
cats(1992) (no abstract
provided) Dow SW & Fettman MJ Seminars in Veterinary Medicine and
Surgery (Small Animal)7 (3) pp198-201, suggested that all cats
with CKD should be supplemented with potassium, even if they do not appear
to have low potassium levels. Some people go further and believe that all
older cats should be supplemented with potassium, whether they have CKD or
Feeding potassium-restricted acidified diets (see
below) to cats with
normal renal function reduces gastro-intestinal absorption of potassium
and may therefore lead to potassium depletion. I therefore would not
recommend feeding such diets to older cats; and these diets should not be
fed to CKD cats anyway (see
I would be wary about giving potassium to any cat with a serum potassium
level over 4.4 - high potassium levels may develop quickly,
particularly as the CKD progresses, and are potentially very dangerous
It is thought
that feeding an exclusively dry food diet may cause chronic dehydration,
which in turn may contribute to the development of CKD. This is not
proven, but it is true that cats may benefit from more water in their diet, particularly
CKD cats, as
do cats with FLUTD.
Nutritional Requirements page has more information on dry food versus wet.
diets over the last ten years have been re-formulated to promote "urinary
tract health", or words along those lines. Essentially, these diets are
acidified, so as to reduce the risk of cats developing
urinary tract disease (FLUTD). Cats with FLUTD tend to have urine that is too alkaline, and are therefore
at risk of developing struvite crystals, which develop in an alkaline
environment. Feeding an acidified diet reduces this risk.
Unfortunately, feeding these diets to cats who are not at risk of FLUTD may lead to urine that is too acidic.
It is speculated that acidified diets may be a factor in the increase in renal
calculi (kidney stones)
i.e. calcium oxalate stones, which develop in an overly acidic
which in turn are a risk factor for
developing CKD. These stones, unlike struvite,
cannot be dissolved by diet - they can only be removed by surgery.
free feeding with Factor-2 (a composite variable composed of fiber,
magnesium, protein, sodium and ash);
and fibre alone.
concluded that free feeding was associated with increased odds of
developing CKD. However, they did not simply free feed the cats; they also
gave them additives. It is therefore not known whether free feeding alone
would give similar results.
I myself have always free fed, and will continue to do so. In the wild,
cats naturally feed multiple times a day. See
Nutritional Requirements for more information on this topic.
Case control study of risk factors associated with
feline and canine chronic kidney disease (2010) Bartlett PC,
Van Buren JW, Bartlett AD & Zhou C Veterinary Medicine InternationalVol 2010, Article ID 957570, states that "There was a
nonsignificant finding that the percent of diet from hunting might be
positively associated with CKD, and further investigation may be
warranted. This question was asked because infectious or toxicologic
agents associated with hunting, such as hantavirus in rodents, may
contribute to renal destruction as a hidden cause of CKD."
Some people on
Tanya's CRF Support Groupbelieve that new carpets and floors contain potential
toxins for cats - several people have noted that their cats developed CKD
shortly after new flooring was laid.
Carpets and other floor coverings may
contain various volatile organic compounds, particularly in the backing.The Carpet
and Rug Institute
in the USA recommends ventilating the area where new carpet is
installed for 48 - 72 hours.
Cats appear to be particularly sensitive to smells;
essential oils, for example, are toxic to cats, who lack the metabolic
pathways to process them. I therefore would recommend keeping cats away
from new carpets and floors for several days after installation, if
TREATING YOUR CAT WITHOUT VETERINARY ADVICE CAN BE
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
change that. I would love it to display perfectly everywhere, but my focus
is on making the information available. When I get time, I'll try to
improve how it displays in other browsers.
You may print
out one copy of each section of this site for your own information and/or
one copy to give to your vet, but this site may not otherwise be
reproduced or reprinted, on the internet or elsewhere, without the
permission of the site owner, who can be contacted via the
This site is a labour of love on my part. 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