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 declines, leading to chronic kidney disease (CKD).

In this article, we will provide a detailed explanation of polycystic kidney disease in cats.

What is feline polycystic kidney disease?

Basic information on polycystic kidney disease

Polycystic kidney disease is a condition where sacs called cysts form in the kidneys, leading to a decline in kidney function and, ultimately, chronic kidney disease. Because PKD is caused by an abnormality in the gene responsible for producing renal proteins, cysts begin forming from an early age, and their number and size increase gradually with age. As a result, normal kidney cells are destroyed, causing a decline in renal function and leading to chronic kidney disease. Due to the genetic nature of the disorder, kittens born to affected cats will also develop the disease.

Cysts typically begin to appear around 10 months of age, and in severe cases, symptoms of kidney disease can develop as early as 3 years old. Cats with polycystic kidney disease have shorter lifespans, with an average life expectancy of about 7 years.

Genetic factors and risk of onset

Polycystic kidney disease has been confirmed as a hereditary condition in Persian cats, American Shorthairs, Scottish Folds, and other breeds. While rare, non-hereditary cases of polycystic kidney disease do exist.

PKD is caused by a gene mutation. It is an autosomal dominant trait, meaning that if one of the pair of genes carries this abnormality, the disease will definitely develop. The gene is passed on to offspring, and if either parent has polycystic kidney disease, 50% of the kittens will inherit the condition. Breeders are advised not to use cats diagnosed with PKD for breeding.

Symptoms and diagnostic methods of polycystic kidney disease

Because symptoms of polycystic kidney disease are often minimal in the early stages, it is frequently discovered by chance during routine health check-ups.

Symptoms of polycystic kidney disease

Polycystic kidney disease presents with the same symptoms as chronic kidney disease, but there are often few signs in the early stages. Owners may sometimes notice the condition because the cat is producing large amounts of dilute urine or drinking more water, but it is often discovered only 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 an odor of urine coming from the body.

Diagnosis of polycystic kidney disease

At a veterinary clinic, the vet will typically start by palpating the kidneys to assess their size and firmness, and will ask about the cat's breed and whether there is any history of PKD among its relatives. They will then assess kidney function through blood and urine tests. In cases of suspected PKD, ultrasound imaging is used to check for the presence of cysts in the kidneys. If symptoms are present, these tests are performed as a matter of course. Genetic testing may be performed to reach a definitive diagnosis.

Treatment for polycystic kidney disease

Polycystic kidney disease is a hereditary condition for which there is currently no established cure in veterinary medicine. Because the disease eventually results in chronic kidney disease, treatment is focused on managing CKD. Treatment for chronic kidney disease primarily involves dietary therapy and medication, with symptomatic treatment being the main focus to improve the quality of life.

Dietary therapy

To reduce the burden on the kidneys, it is necessary to switch to a therapeutic renal diet that is low in protein and phosphorus. Furthermore, as affected cats are prone to dehydration, proper hydration is crucial. Multiple water stations should be set up so that water is always easily accessible.

Drug therapy

Unfortunately, there is no treatment to completely cure polycystic kidney disease, and there is no cure for chronic kidney disease either. Once the condition has progressed to chronic kidney disease, treatment is focused on slowing the progression of the disease and protecting kidney function. Symptomatic therapy is also used to alleviate distressing signs.

To protect the kidneys, medications such as blood pressure reducers, phosphorus binders, activated charcoal to absorb waste products in the blood, antiemetics and antacids for nausea, and erythropoietin preparations to treat anemia associated with kidney disease may be used.

When a cat develops kidney disease, fluids essential to the body are lost through urine, leading to a tendency toward dehydration. Therefore, subcutaneous fluid therapy is often used to maintain hydration and help the body excrete waste products through the urine.

Recently, the relationship between chronic kidney disease and gut microbiota has received attention, with gut bacteria being considered a factor that worsens kidney disease. As a result, probiotic supplements focused on kidney health have emerged. In addition to probiotics, antioxidant supplements are also used in managing kidney disease.

Early detection and care for polycystic kidney disease

Key points for early detection

Polycystic kidney disease is common in Persians, and breeds like the American Shorthair and Scottish Fold, which may have been bred with Persians, are also at risk of developing it. Therefore, not only Persians but also other breeds prone to the condition should be screened for kidney health as early as possible. In cases of PKD, cysts can be identified as early as 10 months of age. For this reason, regular kidney function tests should be conducted starting around the age of one.

While early symptoms of PKD are minimal, once the condition progresses to chronic kidney disease, symptoms such as increased thirst and urination, loss of appetite, and weight loss will appear. If you notice any changes in your cat's behavior, see a veterinarian immediately.

Caring for a cat with polycystic kidney disease

If a cat is diagnosed with PKD but has not yet developed chronic kidney disease, they will be kept under observation, though a transition to a therapeutic renal diet will likely be necessary at an early stage. Using preventative supplements may also be beneficial.

Once the cat develops chronic kidney disease, fluids are lost from the body more easily. Therefore, increase the number of water stations throughout the cat's living space. If your cat does not drink much water, mixing in a little animal-safe oral rehydration solution or broth from wet food can be helpful. Always provide fresh drinking water and change it daily.

It is important to slow the progression of this disease. Follow your veterinarian's instructions regarding medication and dietary therapy, and ensure your cat attends regular check-ups. Eventually, subcutaneous fluid therapy may become necessary. While this can be done at the clinic, many owners perform it at home. Discuss with your veterinarian which option is best based on your lifestyle and your cat's temperament.

Summary

Polycystic kidney disease is a hereditary condition; if a cat carries the gene, they will definitely develop the disease. Unfortunately, there is no cure, so slowing the progression is essential. To spend as much time as possible with your cat, prioritize early detection, early treatment, and regular veterinary check-ups.