Dr. Dana Brooks, an internist at Seattle Veterinary Specialists in Kirkland, answers this week's questions.

danabrooks.jpgDr. Dana Brooks, an internist at Seattle Veterinary Specialists in Kirkland, answers this week’s questions.

Question: What role does the liver play in a dog or cat’s body?

Answer: The liver has many functions. The main functions are detoxification (takes drugs or toxins out) of the blood stream, regulation of blood-sugar levels, maintenance of blood protein and cholesterol levels, production of bile that helps to metabolize fats and production and maintenance of normal blood-clotting factors.

Question: What can go wrong with a liver?

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Answer: The basic disease processes are divided into infection; inflammation; toxicity; cancer; metabolic disease; congenital diseases; and trauma.
Most people think hepatitis (inflammation of the liver) is a viral disease, because this is common in people. But viral hepatitis is very uncommon in dogs. Cats can develop hepatitis as part of the viral disease feline infectious peritonitis.

Infectious causes of hepatitis in dogs and cats are more commonly caused by bacteria, and less commonly by fungal, parasitic or protozoal diseases, such as fungal (blastomycosis), parasitic (roundworm migration in puppies and kittens), protozoal (toxoplasmosis).

Hepatitis can also occur when the body’s immune system attacks itself. This is one of the more common causes of liver problems in dogs and cats.

The cause of the immune-system disturbance is not always apparent. In cats, it is often associated with inflammatory bowel disease (usually associated with food allergies).

Some breeds of dogs can be predisposed to developing hepatitis, such as the Doberman, Labrador and cocker spaniel.

Chronic hepatitis can lead to cirrhosis, which is an irreversible condition in which healthy liver tissue has been replaced by nonfunctioning scar tissue.

Liver toxicities can occur from ingesting certain poisonous mushrooms (Amanita); blue green algae; xylitol (found in sugar-free items such as chewing gum); acetaminophen (Tylenol); and abnormal reactions to some therapeutic medications (arthritis medications, immunosuppressant medications, anticonvulsants, and some antibiotics).