Autoimmune Liver Disease in Dogs

A dog can act healthy with only 30 percent of his liver functioning properly.

A dog's liver is an important organ. It performs many functions that are critical to good health. The liver can function with only 30 percent healthy tissue--after that, the dog will show signs of liver disease. There are several diseases that affect the liver, and some of them are autoimmune in nature. There is some debate whether autoimmune liver disease exists, but if not, certainly other autoimmune diseases can cause liver disease.

Liver Function

The liver is a multi-lobed organ that is responsible for many different functions in a dog's body. It removes toxins from the blood; helps with the production and elimination of bile; is involved in the metabolism of proteins, fats and carbohydrates; and stores blood, glycogen, vitamins and iron. Liver disease affects the whole body.

Autoimmune Disease

The immune system of a dog is composed of white blood cells, antibodies and other substances. The job of the immune system is to protect the body against infection and foreign proteins. In autoimmune disease the immune system malfunctions and begins to attack its own tissues and cells, causing damage and illness.

Autoimmune Liver Disease

There are many different autoimmune diseases that affect dogs, and they can negatively affect the liver, but there is some question as to whether autoimmune liver disease itself exists. According to Dr. Robert Hardy from the Internal Medicine Department at the University of Minnesota "whether dogs or cats are truly affected by immune-mediated liver disease remains to be proven." However, according to Dr. Cynthia Smith of the American Shih Tzu club, "A recent study identified a group of dogs with chronic hepatitis that has specific antibodies against the liver. This is the first definitive evidence that supports the autoimmune theory." The most likely liver disease to have an autoimmune component seems to be idiopathic chronic active hepatitis.

Idiopathic Chronic Active Hepatitis

Idiopathic means of unknown cause. Signs of liver disease occur when more than 70 percent of the liver has been damaged. Early clinical signs include decreased appetite, lethargy, weakness, increased water consumption and increased urination. The dog may vomit and have diarrhea. As the disease progresses it may appear jaundiced, and there may be bleeding into the abdomen. Idiopathic chronic active hepatitis can remain stable or can progress. According to the Dalmatian Club of America, this form of liver disease is believed to have an autoimmune component. Treatment involves the use of immune suppressive medications, among other medicines such as antibiotics and anti-inflammatories.

Other Autoimmune Diseases

Autoimmune hemolytic anemia is a condition where the dog's immune system destroys his red blood cells faster than new ones can be made. Because fewer red blood cells are circulating in the dog's system, there is less oxygen to the tissues and this can cause organ failure, including the liver. Other autoimmune diseases like autoimmune thyroiditis, (common cause of thyroid disease in dogs), immune-mediated thrombocytopenia (destruction of clotting cells) and lupis can cause inflammation of the liver, which impairs its ability to function properly, causing signs of liver disease in affected dogs.

References

• Family Vet: Acute Hepatitis/Acute Hepatic Failure
• University of Minnesota: Chronic Hepatitis/Chronic Active Hepatitis in Dogs; Robert M. Hardy, DVM, MS, Diplomate ACVIM (Internal Medicine)
• American Shih Tzu Club: Clues to Liver Disease; Cynthia Smith, DVM
• The Dalmatian Club of America: Liver Disorders
• Michigan Veterinary Specialists: Chronic Hepatitis - Information for Pet Owners