The liver is an important organ with many functions essential for life.
These functions include detoxifying poisons and drugs, metabolizing fats, storing carbohydrates, manufacturing bile, and producing blood proteins and blood clotting factors. The liver is also a key part of the immune system.
Liver disease has many causes and is often difficult to detect because of the liver's large reserve capacity and its ability to partially regenerate itself when damaged. You'll begin to see signs of liver disease when the reserve capacity is depleted or the regenerative capacity can't keep up.
Causes of liver disease include toxins (poisons and drugs), viruses (including infectious canine hepatitis virus), bacteria (such as Leptospira), parasites, cancers, anatomic abnormalities, immune system disorders, inflammatory disorders, and gall stones. Liver disease also can accompany such diseases as pancreatitis, Cushing's syndrome, heartworm infection, and diabetes mellitus.
Risk factors and detection
Liver disease affects dogs of all ages, but it's most common in middle-aged to older dogs. Certain breeds are predisposed to particular forms of liver disease. For example, portosystemic shunts (a congenital abnormality of the liver's blood vessels) are most common in Yorkshire terriers, Miniature schnauzers, Lhasa apsos, Shih Tzus, retrievers, Irish setters and Irish wolfhounds. Copper-associated hepatitis, a hereditary condition in which copper accumulates in the liver, is most common in Bedlington terriers, Doberman pinschers, and West Highland white terriers.
Unvaccinated dogs are at risk of developing infectious canine hepatitis or leptospirosis. Dogs who roam freely are more likely to encounter toxic and infectious causes of liver disease. Treatment with certain medications for epilepsy, heartworm infection, and fungal infections raise the risk of liver disease. Any underlying medical conditions that alter metabolism, such as Cushing's syndrome, diabetes mellitus, or pancreatitis, also predispose dogs to liver disease.
Signs of liver disease include:
- jaundice (look for yellow-colored gums, eyes, and skin)
- appetite loss
- weight loss
- increased thirst and urination
- vomiting
- abdominal enlargement
- bloody stool
- dark or bloody urine
- bruising or bleeding
- seizures
- behavioral changes, such as weakness and uncoordination and head pressing (pressing the head into such vertical objects as walls).
When to see the veterinarian
If you notice signs of liver disease in your dog, see your veterinarian immediately. The doctor will ask about exposure to toxins, current illnesses, and any medications your dog is receiving. He or she will perform a complete physical examination and may use blood and urine tests, X-rays, ultrasound, and a liver biopsy to determine the cause and severity of the liver disease.
Prevention and treatment
Feeding your dog a balanced diet and not allowing him to roam freely will help prevent liver disease. Routinely vaccinate dogs for infectious canine hepatitis and leptospirosis..
Treatment for liver disease depends on the cause and type of liver disease present. Your veterinarian also must treat any underlying medical conditions. Treatment options include:
Surgery. Your veterinarian may recommend surgery to obtain a biopsy sample, treat an abscess, correct a portosystemic shunt, or to remove gall bladder stones, liver cysts, and isolated liver tumors.
Copper chelators. Zinc salts, D-penicillamine, or trientine treat copper-associated hepatitis.
Diet changes. Some dogs with liver disease develop a condition called hepatic encephalopathy in which the liver's inability to clear ammonia and other substances from the blood results in behavioral changes. Feed dogs with this condition restricted amounts of a food containing high-quality proteins to reduce the amount of ammonia in the blood. Giving your dog lactulose, a laxative, will acidify the intestinal contents and trap ammonia, as well as lower ammonia production by intestinal bacteria.
Antibiotics. Your veterinarian will use antibiotics to treat bacterial infections of the liver. If the doctor finds a liver abscess, he or she will use antibiotics and surgery to treat it.
Antifibrotic agents. These drugs treat fibrosis (cirrhosis) of the liver. Colchicine is the preferred drug for dogs.
Anti-inflammatory and immunosuppressive agents. Inflammation or immune system disorders cause some forms of liver disease. For such cases, your veterinarian may use glucocorticoids (prednisone) or the immunosuppressive drug azathioprine.
Chemotherapeutic agents. If cancer is the cause of liver disease, then treatment may include cancer-fighting drugs.
Treatment of liver disease often requires a combination of these treatments and supportive care, such as intravenous fluid therapy and nutritional supplementation.
Because the liver has some capacity to regenerate, some forms of liver disease can be cured. In other cases, the treatment goals are to slow disease progression and control complications.
