kidney disease, or PKD, is a genetic disease which causes cysts to develop
in the kidneys.
It is most
common in Persian cats.
as the cysts grow, the cat may develop CKD.
What is Polycystic Kidney Disease?
Kidney Disease, known as PKD, is an
autosomal dominant genetic disease of the kidneys which is passed on by one or both
parents; siblings may be unaffected. PKD
affects around 6% of all cats, but appears to be more common in Persian cats,
British Shorthairs and others with Persian
ancestry. One of our cats, Harpsie (left), had PKD.
The distinguishing characteristic of PKD is that cysts are present,
usually on both kidneys, and as the cat gets older, these cysts often
increase in size and multiply. Eventually kidney function may be
diminished to the extent that CKD develops.
Some PKD cats may also show cysts in their liver — Harpsie also had these.
Polycystic kidney and liver disease in cats
(1998) Bosje JT, van den Ingh TSGAM & van der Linde-Sipman JS
Veterinary Quarterly20(4) pp136-139 found that "In 12 of the
18 cats (67%) with multiple rounded cysts in the kidney (PKD) in which the
liver was examined, there were also cystic changes of the liver." It also
found that, out of 27 cases in total, "In 5 cases there was severe
Cats tend to develop PKD around the age of 5 - 7 years (Harpsie was
diagnosed at the age of 7) but seriously affected cats with multiple cysts
can fall ill when they are as young as two. Stress or infection can
accelerate this disease.
However, CKD is not inevitable - it depends how badly the kidneys are
affected, and some PKD cats die from other causes before reaching CKD
status. Harpsie lived to 14, so he managed seven years after his PKD
diagnosis, and although his cysts were growing, he did not have CKD when he
died (he died of cancer).
There is another type of cyst called
perinephric pseudocysts (or
associated with CKD, so if your vet mentions cysts, be sure you know which
type is meant.
PKD is usually
asymptomatic, but a PKD cat may exhibit
polydipsia (increased thirst),
and in some cases the kidneys will feel enlarged (though there are other
possible causes for this, see
Many PKD cats show a slight heart murmur and slightly
swollen kidneys before CKD develops, and male PKD cats are often
susceptible to FLUTD
(feline lower urinary tract disorder), which Harpsie also had.
kidney infections: these are relatively common in PKD cats because the
bacteria can burrow deep into the cysts.
If the disease
progresses so far that CKD results, then the usual CKD symptoms will be
present, and the usual treatments can be used as appropriate.
is generally considered not to be a painful disease. Unfortunately, this
may not apply to cats who progress to severe end stage PKD: these cats may
suffer pain from the cysts growing rapidly and occasionally rupturing.
Sadly, nothing can be done to prevent this, but you do need to watch for it
occurring in a PKD cat so you can discuss your options (such as
with your vet. Infected cysts may also cause pain, and painkillers should
always be considered during treatment for the infection.
The University of California at Davis
identified the gene mutation that causes PKD in 2004.
Feline polycystic kidney disease mutation identified
in PKD1 (2004) Lyons LA,
Biller DS, Erdman CA,
Lipinski MJ, Young AE,
Roe BA, Qin B &
Grahn RA Journal of the American Society of Nephrology15(10) pp2548-55 reports on the discovery.
Gene Testing: USA
The University of California at Davis offers genetic testing at a cost of US$40 per cat. The test can be run as
soon as a kitten is 8-10 weeks old and is almost 100% accurate. You can
obtain the sample yourself, it is obtained by non-invasive means so your
vet does not need to be involved. You will be sent the results via
allow you to see how many cysts are present and how severe the cysts are.
Age-based ultrasonographic criteria for diagnosis of
autosomal dominant polycystic kidney disease in Persian cats
(2018) Guerra JM, Freitas MF, Daniel AG, Pellegrino A, Cardoso NC,
Castro I, Onuchic LF & Cogliati B Journal of Feline Medicine and
Surgery Epub examined whether ultrasound could be used to
consistently diagnose PKD in Persian cats and found that "the presence of
at least one renal cyst was sufficient to establish a diagnosis of ADPKD
in animals up to 15 months of age. Two or more cysts were required for
diagnosis in cats aged 16-32 months, and at least three cysts warranted
diagnosis of ADPKD in animals aged 33-49 months. Finally, four or more
cysts led to diagnosis in cats aged 50-66 months."
Ultrasound is a
reasonably accurate method of diagnosis if it is undertaken by a person
skilled in sonography, and ideally with experience of PKD kidneys.
Repeated scans may need to be taken if the cat is very young as the cysts
may not be visible at that time: it is often hard to detect PKD in cats
less than nine months old.
Cysts are rare
in cats but not all cysts are necessarily PKD; research is still being
done in this area.
If you have a
Persian cat suspected of having
cardiomyopathy (HCM), a type of
heart problem, and are planning to have the heart
examined by ultrasound, I would recommend having the cat's kidneys
examined by ultrasound at the same time in order to rule out PKD. This was
how we discovered that Harpsie has PKD — the cardiologist checked his
kidneys when he checked his heart.
incurable and sadly, there are very few treatments available other than
the standard treatments for CKD. Try to ensure
that your cat leads a stress free life, free of infection and toxicity. A soy protein
diet may possibly help.
the cysts could be drained. However,
Cornell University College of Veterinary Medicine says "It is conceivable, according to Dr.
Goldstein, that cysts within the kidney could be drained with a needle in
a procedure guided by ultrasound imaging. “But there usually are so many
cysts,” he notes, “that this is not a viable option. And even if you did
drain all of them, they would fill up with fluid again.”"
In theory, it
might also be possible to remove the cysts surgically, though the same
issues apply as with draining them. Having said that, one member of
Tanya's CKD Support Group did have her PKD cat's cysts surgically removed
and they did not grow back for four years.
We found that
our PKD cat was very prone to
Around 30-50% of human PKD patients will develop a urinary tract
Renal infections in autosomal dominant polycystic
(1987) Sklar AH, Caruana RJ, Lammers JE & Strauser GD American Journal
of Kidney Disease10(2) pp81-8 reports that these can be
difficult to treat, especially if the infection is in the cysts
(1998) Tanner GA American Society of Nephrology9 pp1242-48 indicated that potassium
citrate may help PKD rats; it is not known if this also applies to cats,
but potassium citrate is an ingredient in Royal Canin's Persian cat food.
Do not supplement potassium without your vet's knowledge and approval.
If the PKD
develops into CKD, then the usual CKD treatments can be used as
appropriate, as described elsewhere in this site.
There is limited research into the treatment of PKD in cats, since the
current focus is on eradicating it from breeding lines, which in the
longer term is of course the best approach.
The University of Bristol Langford Veterinary
Services explains more about
genetic testing and has a graph showing how this is gradually helping to
eradicate the disease.
The following links therefore contain information about research into
certain drugs which appear to slow the progression of the disease in
humans or mice only. I am not aware that anyone has used these treatments
Vascular endothelial growth factor C for polycystic
kidney diseases (2016) Huang JL,
Woolf AS, Kolatsi-Joannou M, Baluk P, Sandford RN, Peters DJM, McDonald
DM, Price KL, Winyard PJD & Long DA Journal of the American Society of
Nephrology27(1) pp69-77 treated the tiny blood vessels around
the cysts in mice with PKD with a growth factor called vascular
endothelial growth factor C (VEGFC). The study found that the blood
vessels normalised and states "these effects were associated with
significant reductions in cystic disease, BUN and serum creatinine
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.
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