Congenital Kidney Disease in Cats

Congenital kidney diseases can be classified into the following categories:

Hereditary: Polycystic kidney disease (PKD) is caused by a genetic anomaly generally affecting Persian cats. PKD is the most prevalent feline congenital kidney disease and is characterized by the formation of fluid-filled sacs within the kidney tissue. Symptoms of PKD usually manifest later in life.

Kidney malformations (renal dysplasia): Renal dysplasia occurs when the animal’s kidneys do not properly develop in the womb. If the malformation occurs on both kidneys, the prognosis is extremely poor, with kittens dying shortly after birth.

Developmental failure (renal agenesis): Renal agenesis occurs when one or both kidneys fail to develop before birth. A cat with renal agenesis can show underdeveloped reproductive organs. If both kidneys fail to develop the prognosis is extremely poor, with kittens dying shortly after birth.

Idiopathic (no known cause): Idiopathic congenital kidney diseases include Kidney Cysts and Perirenal Pseudocysts. Kidney Cysts generally do not cause any symptoms. Perirenal Pseudocysts, or false cysts, are a rare formation of cysts outside of the kidneys, which is generally asymptomatic. Prognosis is generally good, but depends on the size of the mass. These masses may increase in size over time, causing damage to surrounding tissues, including the kidneys. Symptoms include enlargement of one or both kidneys (renomegaly) and abdominal swelling.

Congenital kidney diseases are rare in cats. Most congenital kidney diseases cause renal failure over time. Any cat showing symptoms of renal failure such as excessive thirst and urination, vomiting, or weight loss requires prompt veterinary examination. Some congenital kidney diseases cause no symptoms, and do not affect expected lifespan. Many of these conditions are discovered by accident when investigating other medical issues. Severe congenital kidney diseases are incompatible with life, causing death in kittens shortly after birth.

A cat with one functioning kidney can live a normal life.

Congenital kidney disease can be:

• Hereditary: The most common hereditary congenital kidney disease is polycystic kidney disease (PKD). It is due to a genetic anomaly and it mostly affects Persian cats.

• Developmental: Developmental kidney diseases occur as a result of fetal malformations or the complete failure to develop kidneys in the womb. This is often a random event with no underlying cause.

• Idiopathic: A number of congenital kidney diseases have no discernible cause.

Cats presenting with congenital kidney diseases require the following diagnostics to determine the best course of treatment:

• Physical examination
• Urinalysis
• Genetic testing
• Diagnostic imaging
• Blood work

There is no specific cure for most congenital kidney diseases. Treatment is generally of a supportive nature and includes:

• Fluid therapy: to protect the kidneys
• Dietary modification
• Anti-nausea medication
• Surgery

In the case of malformation or the failure to develop both kidneys, prognosis is extremely poor with kittens dying shortly after birth.

Other congenital kidney diseases may cause renal failure over time. Most of these diseases have no cure, and treatment mainly consists in managing the condition for the cat's lifetime. Some conditions have no impact on the cat’s lifespan or quality of life.

Congenital kidney disease is not contagious. PKD is the only preventable congenital kidney disease. The only way to prevent PKD is to test the animal for the gene responsible for the disease. If the animal results positive, it should be neutered or restricted from breeding.

Any cat can potentially be born with a congenital kidney disease due to idiopathic or developmental causes. Although PKD primarily affects Persian cats it can also affect other breeds , such as British Shorthairs and Himalayans.

• Fluid therapy: to protect the kidneys
• Dietary modification
• Nausea and vomiting medication
• Surgery