Overview of Feline Polycystic Kidney Disease (PKD)
Polycystic kidney disease (PKD), also known as PKD or Autosomal Dominant Polycystic Kidney Disease (ADPKD), is a slowly progressive, irreversible, inherited kidney disease. 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, long-haired and exotic short-haired cats are also affected. It is an inherited condition as an autosomal dominant trait.
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 11 years of age with the clinical signs of the disorder typically occur around the age of seven 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
Screening of healthy cats to determine if disease is present may include:
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.
There is no specific treatment for PKD. Treatment is the same as that for chronic kidney failure of any cause, for example:
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:
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, abdominal ultrasound should be repeated at > 10 months.
Pets affected with PKD that 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.
Genetic testing is available for cats older than 8 weeks of age. A swab of the oral mucous membranes can be collected by the pet owner. The laboratory performing this test is Veterinary Genetics Laboratory at the University of California at Davis. For more information, go to their website: www.vgl.ucdavis.edu.
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 10 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.
There are two forms of PKD in humans: Autosomal dominant PKD (ADPKD) and autosomal recessive PKD (ARPKD). The autosomal recessive form of PKD is uniformly fatal in people at a relatively young age, however the autosomal dominant form (ADPKD) is slowly progressive and is similar to PKD in cats. Genetic studies in cats have shown that PKD in cats in autosomal dominant. This means that if an affected cat is bred to a normal cat, 50 percent of the offspring will be affected.