You might have heard of amyloidosis – but the chances are it’s a bit of a mystery to you, as it’s not a widely known condition. So we asked our vet blogger Amelia to look into the condition…

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What is amyloid?

The body is made up of different types of proteins, from keratin that’s found in hair and nails to collagen found in the skin. Amyloid is a substance made up of abnormally folded proteins that has potential to cause disease. “Amyloidosis” is a general term that refers to the deposition of amyloid protein between cells in organs such as the kidney and liver, there are different types of amyloidosis and the types are classified by the specific protein causing the disease process (Woldemeskel, 2012; Tizard, 2024).

What types of Amyloidosis can affect cats?

The most well-known amyloidosis in cats is known as familial amyloidosis, meaning that there is a genetic component. This familial amyloidosis is most well documented in Abyssinian cats and was particularly prevalent in the 1980s within the breed (ICC, 2018). This type of amyloidosis is caused by serum amyloid A, an acute phase protein being deposited within the kidneys. It is uncommon for other types of amyloidosis to affect the kidneys in this way (Tizard, 2024). Because of this genetic component, selective breeding has been used to reduce the incidence of this disease. 

The second type of amyloidosis seen in cats is the most common amyloidosis in other domestic animals, this is AA amyloidosis, resulting from the misfolding of the acute phase protein serum amyloid A (Woldemeskel, 2012). This can be the result of a long-term inflammatory condition, cancer or can be idiopathic, meaning it has no known cause (Woldemeskel, 2012). This type of amyloidosis has been seen in siamese cats, domestic short hair and various other breeds and amyloid can be deposited in organs such as the kidney, intestines and liver (ICC, 2018). Luckily, both disease types are uncommon in cats.

Are there any symptoms?

Symptoms of amyloidosis vary based on the organ they are affecting. In the case of renal (kidney) amyloidosis, the symptoms seen are those of chronic kidney failure (Tizard, 2024). Sympotms of chronic kidney disease can have an insidious onset, such as weight loss, lethargy and increased thirst and urination. In the cases of familial amyloidosis, this is typically seen in cats younger than six years old (Amyloidosis, 2018). Amyloidosis affecting other organs may show no outward symptoms. In Siamese cats, the common place for amyloid deposition is the liver, therefore symptoms can be that of liver disease and failure, such as jaundice, inappetence and vomiting and diarrhoea (Woldemeskel, 2012).

How is amyloidosis diagnosed?

A definitive diagnosis cannot be made without a biopsy of the affected organ, but your veterinary surgeon may be able to give a presumptive diagnosis based on clinical signs of kidney or liver failure after a period of chronic inflammation of infections. If the affected animal is an at-risk breed, such as an abyssinian or siamese cat, this would increase clinical suspicion of amyloidosis.

What treatments are available?

Unfortunately, there is no treatment available for amyloidosis. There are also no known preventative measures that can be taken. Supportive treatment can be implemented depending on the organ affected. 

In the cases of renal amyloidosis, treatment is the same as for chronic kidney disease. A renal specific diet is used to deliver the appropriate type and amount of proteins, as well as helping to lower phosphate, as hyperphosphatemia is common in renal disease. Supportive treatments can also include gastroprotectants, appetite stimulants, sub- cutaneous fluids to manage dehydration and blood pressure medication, which is a common co- morbidity of kidney disease in cats. 

Although there is no direct treatment available, the familial disease is much less common now due to breeders only breeding from animals not affected by the disease, with time the incidence of the familial disease should continue to become rarer.

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