Cats are typically born with two fully functioning, bean-shaped kidneys that help filter toxins out of the blood. These little organs are very important to the health of your cat so when something is wrong with them, like in a cat with polycystic kidney disease, it's a serious matter. Cat owners should know what signs to watch for in order to best monitor their cat's health and to be able help to catch PKD in its early stages.
What is Polycystic Kidney Disease?
PKD, as polycystic kidney disease is often referred to, is a disease that forms small fluid pockets called cysts on a cat's kidneys. These cysts are typically present from birth and may grow slowly or rapidly. As they cysts get larger and multiply, they make it increasingly more difficult for the kidneys to do their job and ultimately cause the kidneys to fail. PKD can have a large number of cysts or just one large one.
Signs of Polycystic Kidney Disease in Cats
- Increased thirst
- Increased urination
- Decreased appetite
- Weight loss
- Blood in the urine
- High blood pressure
It is impossible to distinguish the symptoms of polycystic kidney disease from other kidney diseases, but these signs are still important to look for. An increase in thirst and urination, a decrease in appetite, weight loss, vomiting, high blood pressure, blood in the urine, and overall lethargy can all be symptoms of PKD. Any changes from what is normal for a cat could be an indication of disease and should be discussed with your veterinarian.
Causes of Polycystic Kidney Disease
Polycystic kidney disease is an inherited disease in cats, so it is passed from cat to cat at birth. It is thought that about 40 percent of Persians have this form of renal disorder, but it may also affect Himalayans, British Shorthair, and other cat breeds that were originally bred from Persians. It is rare in cats that have no Persian ancestry. PKD is due to a mutated gene called PKD1, but what exactly causes this gene mutation is unknown.
There is no cure for polycystic kidney disease, but you can manage the symptoms. Depending on how early in the disease progression PKD is identified, the treatment plan and longevity of the cat will vary. Antibiotics, anti-inflammatories, omega-3 fatty acids, pain medications, appetite stimulants, fluid therapy, dietary plans, and other treatments may be utilized. Drainage of the cysts may be performed but this is only a temporary answer as the cysts will simply refill with fluid.
Monitoring the progression of the disease may be done with the use of X-rays, ultrasounds, blood rechecks, blood pressure measurements, and the observation of symptoms. Once kidney failure has occurred, the decision to euthanize a cat with polycystic kidney disease is often discussed with the veterinarian.
How to Prevent Polycystic Kidney Disease
The best way to prevent polycystic kidney disease in cats is to practice selective breeding. Screening Persians and other at-risk breeds for the presence of PKD1 should be done prior to breeding, and any cats that test positive for this gene should not be bred.
Regular monitoring of kidney function is also recommended for Persians and cats who have Persian ancestry. Even though you cannot prevent your cat from developing polycystic kidney disease, you may be able to slow the progression of the disease by managing the symptoms.
The best way to definitively diagnose polycystic kidney disease is through the use of ultrasound. This will allow a veterinarian to visualize the cysts on the cat's kidneys. In advanced PKD, the cysts are sometimes able to be felt during a physical examination, but in the earlier stages of the disease they won't be palpable. Cats are usually around seven years of age when they start showing symptoms of PKD, but they will have had it since birth and the signs of the disease can appear at any time during their life.
Laboratory testing can also aid in diagnosing a cat with kidney disease, but these tests won't identify that there are cysts, only problems with kidney function. Blood tests can measure waste materials and other levels to check how well the kidneys are working, blood pressure measurements can check for hypertension, and X-rays can be performed to look at the size of the kidneys. These are all useful tools to help manage the disease.
A special genetic test is also available from the University of California in Davis to screen a cat for polycystic kidney disease. This test uses cotton swabs to collect DNA from inside a cat's mouth and then looks for the PKD1 gene. This test only provides a positive or negative result and does not tell you the severity or progression of the disease, though.
Polycystic Kidney Disease. Cornell Feline Health Center
Noori, Z et al. Prevalence of polycystic kidney disease in Persian and Persian related-cats referred to Small Animal Hospital, University of Tehran, Iran. Iranian journal of veterinary research vol. 20,2 (2019): 151-154.