What is
polycystic kidney disease?
Autosomal
Polycystic Kidney Disease (PKD) is a progressive, inherited
condition which causes multiple fluid filled cysts on the
kidneys of Persians and breeds with
Persians in their lines.
Cysts are
present from birth, but start out small, slowly increasing
in size. Cysts can range from very small to several
centimeters in diameter. The increasing size of the cysts
damage the normal kidney tissue, eventually causing kidney
failure.
The number of
cysts & the speed & size in which they grow varies from
Persian cat
to Persian cat. The average age of kidney failure in
Persian cats with PKD
is 7 years, but some Persian cats will suffer from kidney failure at
an earlier age & some cats much later, and in fact succumb
to something other than PKD.
How is PKD
inherited?
Genetic
studies in Persian cats have shown that
PKD in Persian cats is autosomal
(non sex linked gene) dominant. This means only one parent
needs the gene to pass it onto the offspring - the
Persian kittens. There is a 50%
chance of a Persian cat inheriting PKD if a parent has it. If a
cat
is genetically free of PKD it is not possible to pass it
onto offspring.
What are
the signs of PKD in Persian Cats?
How is it
diagnosed in Persian cats?
-
Ultrasound: Ultrasound diagnosis is 98% accurate after
approximately 10 months of age. Ultrasound should be
performed by a veterinarian skilled in the use of
ultrasound.
-
Genetic
Test: A swab from inside the cheeks (buccal swab) is
provided to a specialized laboratory for testing. This
test is 100% accurate.
How are
Persian cats treated for PKD?
There is no
way to slow down the growth of the cysts & they can't be
removed. As the kidneys begin to fail, they lose their
ability to filter out toxins. To understand the treatment it
is necessary to give a brief summary of how the kidney's
work;
-
Kidneys
help control blood pressure by releasing an enzyme
called renin. When blood pressure drops and kidneys
don’t receive enough blood, renin is released; causing
blood vessels to contract (tighten). When blood vessels
contract, blood pressure goes up.
-
Kidneys
filter waste products & excess water from the blood. The
cleaned blood stays in the body & the waste products
leave the body in urine.
-
Stimulation of red blood cell production.
-
They help
maintain the proper balance of acid and minerals,
including sodium, calcium, potassium and magnesium, in
the blood.
Therefore
helping reduce the level of toxins in the Persian cat is important.
Treatment is based on that of a cat with chronic renal
failure & may include:
-
Administration of fluids subcutaneously to treat
dehydration.
-
Prescription diet: Such a prescription diet contains a
lower percentage of protein and less phosphorus than
normal cat food. Persian cats need protein every day for growth,
building muscles and repairing tissue. After the body
uses the protein in the foods, a waste product called
urea is made. Persian cats with kidney failure are not able to
get rid of this urea normally. Damaged kidneys may not
be able to remove phosphorus from the blood. This causes
the level of phosphorus in the blood to become too high.
A high blood phosphorus level may cause the cat to lose
calcium from their bones.
-
Phosphorus
binders may be given. These come in tablet or capsule
form.
-
High blood
pressure (hypertension): Medication may be prescribed if
your cat's blood pressure is too high.
-
Antacids &
anti nausea medication.
-
Erythropoeitine: The kidneys produce a hormone,
erythropoietin, which instructs the bone marrow to
produce red blood cells. Cats with kidney failure often
have a low red blood cell count. Only the human form is
available & some cats may eventually recognize this
substance as foreign & antibodies will be created
against it.
What is the
likely outcome for a Persian cat with PKD?
It really
varies from Persian cat to Persian cat. How many cysts are present, how
large they grow & how quickly they grow. A cat with only a
few small & slow growing cysts may live to an old age &
eventually die from something unrelated to PKD. Other
cats
may have numerous, large & quick growing cysts & die at an
early age.
Is there a
cure?
No,
there isn't a cure for PKD. Persian
cat breeders are advised to test
their cats & if they are found to have
PKD have them altered.
How can I
avoid getting a Persian kitten with the PKD gene?
The best way
to avoid purchasing a Persian kitten with
the PKD gene is to buy from Persian
cat breeders using PKD negative Persian
cats. These are catteries that have DNA
tested all of their Persian cat breeders
for the PKD gene. Remember, if both both parents are
PKD negative, then your Persian kitten will
be negative as well meaning he/she will never get
PKD.
