Hepatic Amyloidosis in Cats
Hepatic amyloidosis refers to the deposition of amyloid in the liver. Amyloidosis belongs to a group of disorders, all sharing a common feature: the pathologic and abnormal deposition of the fibrous protein amyloid into various tissues of the body, disrupting normal functioning of these areas. The accumulation of amyloid often occurs secondary to an underlying inflammatory or lympho-proliferative disorder. For example, when lymphocytes, a type of white blood cell, are produced in excessive quantities, amyloidosis can be a reaction to this condition. Or, it can occur as a familial disorder. Familial amyloidosis has been described in certain breeds of cats, including the Oriental shorthair, domestic shorthair, Siamese, Burmese, and Abyssinian.
Amyloid is a hard, waxy, substance that is the result of tissue degeneration. In this case, amyloid accumulates in the liver and occurs secondary to inflammatory or lymphoproliferative disorders (where lymphocytes, a type of white blood cell, are produced in excessive quantities), or as a genetically acquired familial disorder.
Multiple organs are commonly involved. Clinical signs are usually associated with renal (kidney) involvement. Or it may be associated with high liver enzymes, severe enlargement of the liver, coagulation disorders, liver rupture leading to hemoabdomen (blood in the abdomen), and/or liver failure. Liver amyloid accumulation is often insidious.
Oriental shorthair and Siamese cats are the most commonly predisposed breed to be affected with hepatic amyloidosis. This disease has also been reported in Devon Rex and Domestic Shorthair cats, though rarely. Hepatic amyloid is a familial disorder in Abyssinian cats, with liver signs predominating. The Siamese breed is usually less than five years of age when symptomatic signs of liver disease appear. In other breeds, the typical age for diagnosis is more than five years of age.
Symptoms and Types
- Sudden lack of energy
- Anorexia (loss of appetite)
- Polyuria and polydipsia (excess thirst and excess urination)
- Enlarged abdomen
- Abdominal fluid ‒ blood or clear fluid
- Yellowish skin and/or whites of eyes
- Swelling of the limbs
- Joint pain
- Diffuse pain: head pain (which may be presented as head pressing), and abdominal discomfort
- Familial immune disorders/genetics
- Chronic infection
- Bacterial endocarditis (inflammation of the inner layer of the heart)
- Chronic inflammation
You will need to give a thorough history of your cat's health and onset of symptoms. The history you provide may give your veterinarian clues as to which organs are being primarily affected. Your veterinarian will perform a complete physical exam, with a blood chemical profile, a complete blood count, an electrolyte panel and a urinalysis. These basic fluid tests are essential diagnostic tools for ruling out other causes of disease. The complete blood count will show any anemia which might be present due to internal bleeding or long-term disease, or it may indicate infection. The blood chemical profile may show kidney and liver abnormalities, and the urinalysis may show renal disease.
A clotting profile should also be performed on a blood sample to check the liver’s functionality. X-ray and ultrasound imaging may also reveal abnormalities in organs where amyloid might be collecting. If necessary, a minor surgery can also be performed to collect a sample for biopsy of the liver and/or other organs.
Cats with swelling in the joints should have joint taps taken. Cytology – a microscopic examination of the cells present in the fluid - of these samples can be performed to confirm or rule out the presence of malignancies in the cells. The composition of any fluid that has built up in the abdomen can also be analyzed at the laboratory.
There is no cure for amyloidosis, but supportive care is very helpful. Blood transfusions should be administered if your cat has recently lost a lot of blood. Fluid therapy and possible diet changes will need to be undertaken. Each patient should have its diet tailored to suit the organ function that is being affected most. If feline patients have a fractured liver lobe, surgery may be necessary.
Living and Management
This syndrome is difficult to treat and has a guarded to poor prognosis. Most animals will have episodes of fever and cholestasis, where bile cannot flow from the liver to the duodenum (small intestine). Some cats will benefit from medication, with resolved clinical signs and diminished hepatic amyloid. However, cats surviving liver hemorrhage eventually succumb to renal failure. Your veterinarian will schedule follow-up appointments with you for your cat as is necessary to monitor its organ function.