What Is Feline Polycystic Kidney Disease? A Vet Explains Symptoms, Diagnosis, and Treatment

Polycystic kidney disease (PKD) is a hereditary disease in which sacs called cysts form in the kidneys and gradually enlarge. Eventually, kidney function deteriorates, leading to chronic kidney disease.

This article explains polycystic kidney disease in cats in detail.

What is Feline Polycystic Kidney Disease (PKD)?

Basic Information about Polycystic Kidney Disease

Polycystic kidney disease is a condition in which sacs called cysts form in the kidneys, leading to a decline in kidney function and eventually developing into chronic kidney disease. Polycystic kidney disease is caused by an abnormality in the gene that produces kidney protein, so cysts form from a young age and gradually increase in number and size with age. As a result, normal kidney cells are destroyed, kidney function declines, and chronic kidney disease develops. Due to the genetic abnormality, cats born to a cat with this disease will also develop it.

Cysts appear around 10 months of age, and symptoms of kidney disease can develop as early as 3 years of age. The lifespan of cats with polycystic kidney disease is short, with an average lifespan of about 7 years.

Genetic Factors and Risk of Onset

Polycystic kidney disease has been identified as a hereditary disease in Persian cats, American Shorthairs, and Scottish Folds, among others. Although rare, non-hereditary polycystic kidney disease also exists.

Polycystic kidney disease is caused by a genetic abnormality. It is an autosomal dominant inherited condition, meaning that if there is an abnormality in one of a pair of genes, the disease will inevitably develop. The gene is passed on to offspring, and if one parent has polycystic kidney disease, 50% of the kittens born will develop the disease. Breeders are instructed not to use cats diagnosed with polycystic kidney disease for breeding.

Symptoms and Diagnosis of Polycystic Kidney Disease

Polycystic kidney disease often goes unnoticed in its early stages and is frequently discovered by chance during routine health check-ups.

Symptoms of Polycystic Kidney Disease

Polycystic kidney disease exhibits the same symptoms as chronic kidney disease, but there are often few symptoms in the early stages. While it may be noticed when the cat produces a lot of dilute urine and drinks more water, it is often discovered at an advanced stage.

The main symptoms of polycystic kidney disease include increased thirst and urination, loss of appetite, and vomiting. Other symptoms may include stomatitis, diarrhea, constipation, and a urine odor from the body.

Diagnosis of Polycystic Kidney Disease

At the veterinary hospital, the veterinarian first evaluates the size and hardness of the kidneys by palpation and asks about the cat's breed and whether there are any relatives with polycystic kidney disease. Then, blood and urine tests are performed to assess kidney function. In cases of polycystic kidney disease, an ultrasound examination is performed to check for cysts in the kidneys. If symptoms are present, these examinations are always performed. Genetic testing may be performed to make a definitive diagnosis.

Treatment for Polycystic Kidney Disease

Polycystic kidney disease is a hereditary condition, and there is currently no established cure in veterinary medicine. Since it eventually leads to chronic kidney disease, treatment focuses on managing chronic kidney disease. Treatment for chronic kidney disease primarily involves dietary management and medication, with the main goal being symptomatic relief to improve the cat's quality of life.

Dietary Therapy

To reduce the burden on the kidneys, it is necessary to switch to a therapeutic kidney diet that is restricted in protein and phosphorus. Additionally, dehydration is common, so hydration is crucial. Multiple water stations should be set up to ensure constant access to water.

Pharmacotherapy

Unfortunately, there is no treatment that completely cures polycystic kidney disease. Likewise, there is no cure for chronic kidney disease. When polycystic kidney disease progresses to chronic kidney disease, treatment focuses on slowing the progression of chronic kidney disease and protecting the kidneys. In addition, symptomatic treatment is administered to alleviate painful symptoms.

Medications used include blood pressure lowering drugs to protect the kidneys, phosphate binders to excrete excess phosphorus in the blood, activated charcoal to adsorb waste products in the blood, antiemetics and antacids to suppress nausea, and erythropoietin preparations to improve anemia caused by kidney disease.

When kidney disease occurs, essential body fluids are excreted as urine, leading to dehydration. Therefore, subcutaneous fluid therapy is administered to replenish fluids and facilitate the excretion of waste products in the urine.

Recently, the relationship between chronic kidney disease and intestinal bacteria has garnered attention, with intestinal bacteria being considered a factor in the worsening of kidney disease. Therefore, lactic acid bacteria preparations specifically for kidney disease have emerged. In addition to lactic acid bacteria preparations, supplements with antioxidant properties are also used for kidney disease.

Early Detection and Care of Polycystic Kidney Disease

Key Points for Early Detection

Polycystic kidney disease is common in Persian cats, and American Shorthairs and Scottish Folds that have been bred with Persian cats may be at risk. Therefore, Persian cats, as well as cat breeds known to be predisposed to the disease, need to undergo kidney examinations as early as possible. In cases of polycystic kidney disease, cysts can be observed as early as around 10 months of age. Therefore, regular kidney function examinations should be performed starting from about 1 year of age.

While there are few early symptoms of polycystic kidney disease, if it progresses to chronic kidney disease, symptoms such as increased thirst and urination, loss of appetite, and weight loss may appear. If you notice any unusual changes in your cat, consult a veterinarian immediately.

Care for Cats with Polycystic Kidney Disease

Even if polycystic kidney disease is diagnosed, if kidney disease has not yet developed, the cat will be monitored, but a switch to a therapeutic kidney diet will be necessary at an early stage. Using preventive supplements may also be beneficial.

If chronic kidney disease develops, the cat will tend to lose water from its body. Therefore, increase the number of watering stations in the cat's living space. If the cat doesn't drink much water, you can mix in some animal oral rehydration solution or the broth from wet food. Always provide fresh water and change it daily.

For this disease, it is crucial to slow its progression. Therefore, follow your veterinarian's instructions for medication and diet therapy, and schedule regular check-ups. Ultimately, subcutaneous fluid therapy will be necessary. This can be done at the clinic, but many owners also perform it at home. Discuss with your veterinarian which option is best, considering your lifestyle and your cat's personality.

Summary

Polycystic kidney disease is a hereditary condition, and if a cat carries the gene, it will inevitably develop the disease. Unfortunately, there is no cure, so slowing its progression is crucial. For a longer life together, aim for early detection, early treatment, and regular check-ups.