What is PKD?

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 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.

Source: http://www.cat-world.com.au/PolycysticKidneyDisease.htm