Renal Amyloidosis in Cats

Abyssinian cat up close, side view of face
Abyssinians are more likely to develop renal amyloidosis than other breeds.

Getty Images/Josef Timar 

There are several different types of kidney diseases that can affect cats. Renal amyloidosis is a specific condition that occasionally occurs in cats and it is a serious disease. Knowing more about this deadly problem can help a cat owner keep their pet healthy as long as possible.

What is Renal Amyloidosis?

Renal amyloidosis is an accumulation of amyloid around kidney cells. Amyloid is a type of inflammatory protein that can build up around different tissues and organs in the body, including the kidneys and liver. Renal amyloidosis is a specific type of amyloidosis that affects the kidneys of cats and is a serious disease that has no cure.

The kidneys are two bean-shaped organs inside the abdomen of a cat. They play an important role in filtering wastes out of the body. If the kidneys cannot function properly, such as in a cat with renal amyloidosis, kidney failure and eventual death results.

Signs of Renal Amyloidosis in Cats

  • Dehydration
  • Excessive thirst
  • Excessive urination
  • Weight loss
  • Vomiting
  • Diarrhea
  • Swollen legs

The symptoms of renal amyloidosis are the same as most other kidney diseases in cats.

Excessive thirst and urination are usually the first things a cat owner sees in a cat with renal disease. A cat with renal amyloidosis may empty its water bowl more quickly than usual, spend more time drinking water or seeking out water from other places such as bird baths, drinking glasses, and the sink, and leave bigger wet spots in the litter box from the excessive urination that results.

Because of the excessive urination, dehydration can occur even when cats are drinking a lot. Dehydration can cause a cat's skin to "tent" meaning if the skin is picked up around the neck and gently pulled away from the body it will form a "tent" instead of going right back to its normal place on the body. This indicates a lack of fluid within the cells of a cat. It is very serious and can cause a cat to feel really sick. The build up of waste products in the body can also cause a cat to feel very ill, stop eating, and start vomiting. If a cat doesn't feel well it won't eat and weight loss will naturally occur. Weight loss can occur in cats with kidney disease, even if they are eating well, due to a process called cachexia, which is a loss of muscle that occurs in animals with chronic disease.

Finally, swollen appendages could result from renal amyloidosis. With amyloidosis, the kidney's filtering system gets clogged which can lead to protein being lost in the urine. Protein helps keep fluid in the blood vessels. When protein levels in the blood drop to low, it can cause fluid build-up in the legs in the lymphatic system. This is called lymphadema.

Causes of Renal Amyloidosis

Certain breeds of cats are more likely to develop renal amyloidosis than others but the specific cause of this disease is not known. Abyssinians and Oriental cat breeds such as the Siamese are thought to have genetic predispositions to developing renal amyloidosis. Other than being fairly breed specific, it is thought that chronic inflammation from disease such as chronic kidney infections, and kidney cancer can lead to renal amyloidosis.

Diagnosing Renal Amyloidosis

In most cases of renal disease, cats will have misshapen or shrunken kidneys. But with renal amyloidosis, cats may have normal sized kidneys. This can make it difficult for a veterinarian to diagnose renal amyloidosis solely on feeling the kidneys during a physical examination or visualizing them on an X-ray or ultrasound. Blood tests to look at red and white blood cells along with kidney levels, as well as a urine sample to check the urine concentration and protein levels will be needed for an initial diagnosis. To make a definitive diagnosis of renal amyloidosis, a biopsy of the kidney's is needed so that the cells can be looked at microscopically.

Treatment

Renal amyloidosis may not be very common in cats but for those that do develop it there is unfortunately no cure. Managing the symptoms of the disease may prolong the quality of life and slow the disease progression for a cat with renal amyloidosis but there is no reversal or stopping of this protein build-up. Symptomatic treatment may include fluid administration, dietary changes, and medications to entice a cat to eat, address vomiting and diarrhea, manage pain, and treat any secondary problems such as hypertension.

How to Prevent Renal Amyloidosis in Cats

Abyssinian and Oriental cat breeds should be regularly monitored for renal amyloidosis. Even though no one knows exactly what causes this disease, if signs of renal amyloidosis are discovered early enough the progression may be able to be slowed down with medications and specific dietary changes. Annual blood screening for young cats and twice yearly screenings for older cats is often recommended to monitor kidney health.