Hepatic Amyloidosis in Dogs

 

Amyloidosis refers to a group of disorders that share a common feature: the pathologic abnormal deposition of a fibrous protein called amyloid into various tissues of the body.

 

Hepatic amyloidosis is the deposition of amyloid in the liver. 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. Most affected dogs are thought to have reactive or secondary amyloidosis affiliated with an underlying primary inflammatory disorder. Familial amyloidosis has been described in certain dog breeds. The most commonly affected breeds are beagles, shar peis, and foxhounds.

 

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.

 

Certain Chinese shar-pei dogs with cyclic fevers (known as shar-pei fever syndrome), Akitas with cyclic fever and multiple joint inflammations, and collies with “gray collie syndrome” are predisposed to developing amyloidosis. They usually develop renal signs first although some develop symptoms of liver failure first.

 

Symptoms and Types

 

• Episodic fever and swollen hocks (Shar-peis)
• Episodic joint inflammation, pain, and signs of meningitis (Akitas)
• Sudden lack of energy
• Anorexia (loss of appetite)
• Polyuria and polydipsia (excess thirst and excess urination)
• Vomiting
• Pallor
• Abdominal fluid – blood or fluid
• Yellowish skin and/or whites of eyes
• Enlarged abdomen
• Swelling
• Joint pain
• Diffuse pain: head pain, and abdominal discomfort

 

Causes

 

• Familial immune disorders/genetics
• Chronic infection
• Cyclic neutropenia (gray collie syndrome)
• Bacterial endocarditis (inflammation of the inner layer of the heart)
• Chronic inflammation
• Tumor

 

 

 

Diagnosis

 

You will need to give a thorough history of your dog'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.

 

Dogs 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.

 

Treatment

 

There is no cure for amyloidosis, but supportive care is very helpful. Blood transfusions should be administered if your dog has recently lost a lot of blood, and 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. Surgery intervention may be necessary if there is a fractured liver lobe,.

 

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 dogs will benefit from medication, with resolved clinical signs and diminished hepatic amyloid. Shar-peis may survive more than two years. However, Akitas with cyclic clinical signs have a grave prognosis. Your veterinarian will schedule follow-up appointments with you for your dog as is necessary to monitor its organ function. Your veterinarian will schedule follow-up appointments with you for your dog as is necessary to monitor its organ function.