Kidney amyloidosis is an uncommon disorder of protein metabolism in which a protein called amyloid is abnormally deposited in the kidneys, causing excessive protein loss in the urine.

Kidney amyloidosis is uncommon in cats, except for Abyssinian cats, in which it is familial. Chronic inflammatory diseases can predispose cats to the development of kidney amyloidosis, however only a small percentage of cats with chronic inflammatory conditions develop amyloidosis, thus, other factors must also be important in the development of amyloidosis. These other factors are poorly understood. Most cats with amyloidosis do not have discernible inflammatory or infectious conditions at the time of diagnosis.

Most cats with kidney amyloidosis are old at the time they are diagnosed with the disease. The average age is 7 years. The hereditary form tends to strike earlier; Abyssinian cats are less than 5 years of age on average, at the time of death or euthanasia from the disease.

Amyloid deposits in the kidneys lead to eventual kidney failure. Signs of kidney failure include anorexia, lethargy, and weight loss. Excessive water consumption and urination is another common sign of kidney failure. Occasional vomiting is also seen.
        
Kidney amyloidosis causes excessive protein loss in the urine. One of the proteins lost in the urine is a protein responsible for preventing the blood from clotting. As a result, affected cats are more susceptible to formation of blood clots. These clots tend to lodge in the lungs, causing clinical signs that may not be obvious, ranging from labored breathing to major respiratory distress.

Excessive urinary loss of a protein called albumin may lead to ascites, which is an accumulation of fluid in the abdomen. It may also lead to edema, which is a swelling of the limbs and/or face. Ascites and edema are relatively uncommon occurrences in cats with kidney amyloidosis.