What is amyloidosis?
Amyloidosis occurs when proteins called "amyloid" are deposited outside cells in various tissues and organs, such as the kidneys and liver, which causes tissue damage and organ dysfunction. Amyloidosis is uncommon in cats except for Abyssinians, Siamese, Burmese, Tonkinese, Devon Rex, and oriental shorthair breeds.
While certain family lines of Siamese cats are identified as predisposed, there is no clear genetic profile in the affected cats. Most cats diagnosed with amyloidosis are older than 7 years of age, although the age range at diagnosis can be from 1 to 17 years of age. It appears that the risk for developing amyloidosis increases with age. Certain Siamese cats with hereditary amyloidosis may be diagnosed as early as 1 to 4 years of age.
What are the signs of amyloidosis?
The signs of amyloidosis depend on the organ system that is affected, but kidney involvement is most common. The affected cat may lose their appetite, become lethargic, have increased drinking and urinating, experience weight loss, vomiting, and diarrhea. In some cases, fluid builds up under the skin, in the abdomen (belly), and/or in the chest cavity. If the disease progresses, the cat may develop signs specific to kidney failure including:
- mouth ulcers
- extreme weight loss
- ongoing vomiting
Some affected cats develop blood clots and, depending on the location, there may be clinical signs such as difficulty breathing or weakness in one or both rear legs.
Siamese and Oriental shorthair cats are the exception. In these breeds, affected cats are prone to severe liver amyloidosis that leads to liver rupture and bleeding. Signs may include weakness, pale gum color, distended abdomen, rapid heart rate, rapid breathing, abdominal pain, and collapse.
What causes amyloidosis?
Chronic infection, chronic inflammation, and certain types of cancer have been associated with the development of amyloidosis. Hereditary amyloidosis occurs in certain breeds such as Abyssinian, Siamese, Devon Rex and other Oriental cat breeds with different organs being affected.
Is there any treatment for amyloidosis?
If the cat with amyloidosis develops kidney failure, hospitalization with IV fluids may provide a way to stabilize the condition. Once stabilized, the cat may be able to tolerate outpatient management focused on kidney support with proper nutrition and any necessary medications. There is, however, no specific medication for the treatment of amyloidosis in cats. Some cats with amyloidosis also develop hypertension (high blood pressure) that should be treated. Any underlying condition like cancer, infection, or inflammation should be treated if possible.
Ongoing monitoring of organ system function, fluid balance, and blood pressure is important in cats with amyloidosis. Any emerging symptoms can then be treated as soon as they are identified. Amyloidosis is a devastating disease, and if the kidneys are affected, most cats survive less than one year. Cats who are mildly affected may not develop kidney failure for some time and therefore may have a nearly normal life expectancy.