The liver is the largest gland in the body and serves many complex functions. Because of its key role in many metabolic processes, the liver is subject to damage by a wide variety of diseases.

Liver disease is any destructive or metabolic disorder involving the liver and is not limited to any particular age or breed. Often a specific diagnosis cannot be made, but some possible causes of liver disease include viral and bacterial infections, poisonous substances eaten by the pet, congenital abnormalities and cancer. In cats, not eating for two to three days may result in a life-threatening disease called hepatic lipidosis, which occurs when fat builds up too high in the liver.

The more common signs of liver disease in dogs and cats include lack of appetite and weight loss, depression, jaundice, increased thirst, and dark colored urine. Other signs of illness associated with liver disease can include ascites (fluid build up in the abdomen), pale gums and associated bleeding tendencies. The pet's abdomen may be enlarged as a result of the fluid accumulation and enlargement of the liver. This sometimes leads owners to think their pet is obese or has gained weight.

The above signs may appear very quickly or develop slowly. Other diseases may cause similar signs so it is important to take your pet to your veterinarian for examination. If your veterinarian suspects liver disease after a thorough physical examination, he or she will recommend blood work, abdominal X-rays, and other diagnostic procedures that are thought necessary to diagnose the problem and treat it correctly. The important step is to recognize that there is a problem that needs to be addressed.

(The authors are Dr. Steven B. Holzman, Dr. William R. Haagenson and Dr. Kathleen Tapley. They are associated with the Nassau-Suffolk Veterinary Hospital of Farmingdale.)