Polycystic Kidney Disease in Cats

PKD in cats usually begins to appear through kidney-related clinical signs at around seven years of age, but can affect the cat in earlier stages of life. Common symptoms a cat owner may note at home are those associated with kidney failure including lethargy, polydipsia, polyuria, vomiting, depression and weight loss. Upon veterinary diagnostic exams, the kidneys will appear large in size and the biochemistry profile (a blood test used to detect hormones released by the body’s organs) will indicate abnormal kidney function. Most felines that are diagnosed with (PKD) are in advanced stages of kidney disease, which may likely be fatal. However, there is a (PKD) screening test available for breeders with felines at risk for the disease that will aid in the prevention of the gene abnormality from being passed to future generations. 

Polycystic kidney disease (PKD) in cats is a form of kidney disease, characterized by numerous fluid-filled cysts within the two vital organs. The cysts are present at birth, progressively growing in size and compromising the healthy kidney tissues, which leads to kidney failure. Polycystic kidney disease (PKD) in cats is an inherited disease found in Exotic Shorthaired cats and Persians. The actual name your veterinarian may give this hereditary kidney abnormality is autosomal dominant polycystic kidney disease, abbreviated AD-PKD, as it is a single pair of genes, or “autosomal dominant” genes, that will determine whether or not a kitten will possess PKD. This means that if only one of the parents, either the father or the mother, are affected by PKD, the affected gene will remain dominant and pass the kidney disease onto about half of the offspring.

The symptoms of polycystic kidney disease in cats are related to general kidney failure and disease. The progressive growth of cysts within these vital organs will slow down their function of filtration, which may lead to complications in the bladder and abdominal pain. Additional symptoms related to PKD in cats can include: 

• Lethargy 
• Polydipsia (excessive thirst) 
• Polyuria (excessive elimination of urine) 
• Vomiting 
• Depression 
• Weight loss 
• Anorexia 
• Poor hair coat 
• Listlessness 
• High blood pressure 
• Anemia 
• Weakness 
• Blindness 
• Seizures 
• Ataxia 
• Presence of blood in vomit or diarrhea 

Autosomal dominant polycystic kidney disease, abbreviated AD-PKD, is caused by a single pair of genes, or “autosomal dominant” genes, that will determine whether or not a kitten will possess PKD. This means that if only one of the parents, either the father or the mother, are affected by PKD, the affected gene will remain dominant and pass the kidney disease onto about half of the offspring. If a cat is found with one PKD gene, then that feline is said to be heterozygous, whereas a feline that possesses two PKD genes is referred to as homozygous. If two cats of heterozygous nature mate, the litter has a less likely chance of infecting all kittens; roughly 75 percent are estimated. If two cats of homozygous mate together, however, will result in an infection of the entire litter of kittens. 

Clinical signs often suggest complications with a cat’s kidneys, so the veterinarian will likely run diagnostic exams to adhere to this observation. A biochemistry profile and complete blood count will likely be conducted to take note of the functionality of the kidneys. As the kidneys filter toxins from the blood to be passed in the urine, a urinalysis (examination of the urine), may also prove to be effective in diagnosing a kidney problem. Determining whether a feline has PKD requires a differential diagnosis. The veterinarian will radiograph the location of the kidneys, which often reveals enlarged kidney organs. The diagnosis will proceed to an ultrasonic test, revealing the presence of cysts. The veterinarian will take your cat’s breed, age and genetic history into consideration before requesting a gene test. A genetic test is available for cat suspected of having PKD and only requires a small blood sample, or mouth swab.

Polycystic kidney disease has no known cure and treatment is only prescribed as supportive life care for the feline. Potassium supplements or IV fluids are commonly given to felines suffering from PKD, as failure of the kidneys often lowers potassium levels in the blood. The blood cells themselves can also be affected, resulting in anemia that may require iron supplementation, as the red blood cells carry iron to circulate throughout the body.

As PKD progressively worsens as the cat ages and there is no known treatment, the prognosis for cats affected by this disease is rather poor. To improve the quality of a cat’s life, the veterinarian may recommend a diet change, low in sodium, and supplement absent minerals or vitamins. Routine testing to evaluate the cat’s blood electrolytes are to be expected to balance the prescribe treatments over time.