Overview of Feline Polycystic Kidney Disease (PKD)
Polycystic kidney disease (PKD) in cats, also known as PKD or Autosomal Dominant Polycystic Kidney Disease (ADPKD), is a slowly progressive, irreversible, inherited kidney disease that can occur in cats. It is characterized by development of cysts in the kidney and sometimes also the pancreas, liver and/or uterus. Ultimately, PKD can result in renal failure, with clinical signs similar to those of cats with naturally occurring kidney failure.
Below is an overview of Polycystic Kidney Disease in cats followed by in-depth information about the diagnosis and treatment of this condition.
Polycystic kidney disease is most common in Persian and Persian-related cats. Himalayans, longhaired and exotic shorthaired cats are also affected. There has been an increased incidence in domestic shorthair cats. It is an inherited condition as an autosomal dominant trait. It has been estimated that polycystic kidney disease affects 40% of all Persians and Persian-related breeds.
The disease can occur in either gender and it can be diagnosed in kittens less than 6 months old. It may be diagnosed in some cats between 3 and 10 years of age with the clinical signs of the disorder typically occurring around the age of 7 years. It is estimated that 40% of all Persian and Persian related cats are affected. Not all cats with PKD will develop kidney failure.
What to Watch For
Signs of polycystic kidney disease can include some or all of the following:
- Reduced appetite or anorexia
- Increased thirst and urination (Polydipsia and Polyuria)
- Weight loss
Diagnosis of Polycystic Kidney Disease
Screening of healthy cats to determine if a disease is present may include:
- Genetic testing is available for cats older than 8 weeks of age
- Radiography with or without contrast
- Ultrasound is the test of choice for establishing the diagnosis
Clinically ill cats may have tests that include:
- Physical examination findings and routine laboratory data are recommended for diagnoses. The results will vary depending on the severity of the disease.
- Complete blood count
- Serum biochemical profile
- Blood pressure
Treatment of Polycystic Kidney Disease
There is no specific treatment for PKD. Treatment is the same as that for chronic kidney failure of any cause, for example:
- Restricted protein and phosphorus diets
- Fluid therapy that may include subcutaneous fluids
- Phosphorus binders
- Calcitriol (Vitamin D)
Home Care and Prevention
There is no specific home care for cats with PKD that have no symptoms. Cats with PKD that have developed chronic kidney failure undergo home care typical for that condition including:
- Prescription diet
- Subcutaneous fluid therapy
There is no way to slow the progression or prevent the onset of chronic renal failure once PKD has been diagnosed. Prevention requires responsible breeding to eliminate PKD from Persians and Persian-related breeds. Screening using abdominal ultrasound is recommended in kittens older than 16 weeks. If this screening is negative, an abdominal ultrasound should be repeated at > 10 months.
Cats affected with PKD should be neutered and not bred. Affected cats with no signs of illness should be monitored by checking laboratory work (including BUN, Creatinine, and urine specific gravity) every 6 to 12 months to evaluate progression of the disease to kidney failure. The rate of progression of polycystic kidney disease varies.
Genetic testing is available for cats older than 8 weeks of age. A swab of the oral mucous membranes can be collected by the cat owner. The laboratory performing this test is Veterinary Genetics Laboratory at the University of California at Davis. For more information, visit their website.
In-depth Information on Polycystic Kidney Disease in Cats
Polycystic Kidney Disease (PKD) is a slowly progressive, irreversible, inherited kidney disorder in Persian and Persian-related cats. Although reported in the veterinary literature for approximately 30 years, the disease and its genetic mode of inheritance has only been clearly understood in the last 15 years.
The disorder is present at birth. Multiple small cysts slowly grow in size, causing the kidney to enlarge dramatically. The cysts replace the normal kidney tissue, while kidney function continuously declines. The cysts can vary in size, from less than one millimeter to greater than one centimeter. The older an affected cat gets, the larger and more numerous are the cysts. PKD often progresses to cause clinical signs of kidney failure late in the cat’s life, with the average age being around seven years, although the slowly progressive nature of the disorder results in some cats not developing clinical kidney disease and death.
Clinical signs of PKD are non-specific and are similar to those seen in cats with chronic renal failure of any cause. These include depression, decreased appetite or anorexia, excessive drinking, excessive urination, weight loss, and sporadic vomiting.