 What is Polycystic Kidney Disease - PKD?Polycystic Kidney Disease is an inherited kidney disease that has
been found in Persian/Exotic cats. Feline Polycystic Kidney Disease (PKD) has been
reported sporadically in the literature since 1967, but actual study into this renal
disease did not begin until 1990. In1990 an affected female Persian was referred to the
Ohio State University teaching hospital with symptoms of renal failure.
Offspring of this
female were used to start a colony and begin research into this condition.
How is PKD diagnosed?
PKD is most easily diagnosed by ultrasound,
which can identify the disease very early in its course. All that is required is a
mid-ventral abdominal area hair-clip and a short time period for imaging to detect the
possible presence of cysts. It takes a few minutes, with little or no sedation needed. It
is very important that experienced personnel and
proper equipment perform the ultrasound! When so, ultrasound diagnosis is 98% accurate
after approximately 10 months of age. The frequency of the transducer has to be
7,5 MHz - 10
MHz, with a greyscale of 256. The higher frequency, the better details. A
DNA-test for ADPKD in cats is not available at this time.
What
does this disease cause in cats?
Polycystic Kidney Disease is a slowly progressive
disease. It clinically shows up later in life (late onset), with enlarged kidneys and
kidney dysfunction on average at seven years of age. The condition is inherited and cysts
are present from birth. The size of cysts can vary from less than one
millimeter to
several centimeters, with older animals having larger and more numerous cysts. Problems
occur when these cysts start to grow and progressively enlarge the kidney, reducing the
kidneys' ability to function properly. The ultimate end is kidney failure.
Some of the clinical signs are depression, lack of
or reduced appetite, excessive thirst, excessive urination and weight loss. There is a
marked variability in how quickly individual cats succumb, with the possibility of the
symptoms of PKD developing late enough in life that the cat can die of other causes before
kidney failure. However, kidney failure is certain when and if the cysts grow and cause problems.
How
does a breeder eliminate PKD from a breeding colony/cattery?
As PKD is the result of an autosomal dominant gene,
it is relatively easy to track and eliminate from the breeding population. All breeding
animals need to have an ultrasound to detect the possible presence of kidney-cysts. The
quickest way to eliminate the problem is to neuter or spay the affected individuals and
only breed from PKD-negative cats. A PKD-negative cat is also genetically PKD-free!
If a particular
breeding-stud or queen is extremely
valuable, there is still a possibility to produce PKD-negative kittens. To achieve that,
one parent has to be PKD-negative and the other parent heterozygous in its gene. Please,
read more about this in the article «Autosomal Dominant Polycystic Kidney
Disease in Persian Cats», by Dr David S.Biller, Dr Stephen P. DiBartola and Wilma J.
Lagerwerf. The article was published in the Cat Fanciers’ Magazine, Feb 1998, and can
also be found on the CFA home page.
Other reference articles are: Biller DS. et al;
«Inheritance of Polycystic Kidney Disease in Persian Cats», Journal of Heredity, 1996
Jan; 87(1): 1-5 and Eaton KA, et al; «Autosomal Dominant Polycystic Kidney Disease in
Persian and Persian-cross Cats», Vet Pathology 1997, Mar;34(2): 117-126.
What can you do?
It is theorised that PKD is more common in
Persians/Exotics than what is currently diagnosed. With more studies and published
information about this disease, breeders and veterinarians can work to establish PKD-free
breeding programs.
You can help in this! You can have your breeding
cats ultrasounded, and aim to breed from PKD-negative individuals as soon as possible.
Copyright © Professor David S. Biller, DAVM, DAVCR, Kansas State University, USA,
and Marie Thiers, Sequoyahs Persians, Sweden
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