Canine Liver Disease
The liver is a vital organ, crucially involved in the process of digestion and the absorption of nutrients, and in filtering the blood to remove toxins. In addition, the liver manufactures proteins to assist in blood-clotting. It also and stores fat- soluble vitamins D and E. Because of the liver's importance, liver disease is significant and frequently life-threatening.
Causes of Canine Liver Disease
Liver disease can be caused by a great number of factors including infectious diseases, parasites, underlying conditions and certain chemicals and plants. Any of the following may be responsible for dysfunction of the liver:
- Hepatitis
- Leptospirosis
- Heartworm infection
- Cushing's syndrome
- Diabetes
- Tumors
- Toxic chemicals such as lead
- Certain medications
- Some plants and molds
- Blockage of the bile duct
Medications that may harm the liver, especially with prolonged or excessive use, include antibiotics, antifungals, anesthetic gases, analgesics, anticonvulsants and corticosteroids. Plants that may cause liver damage include blue-green algae, certain mushrooms, ragwort and aflatoxin, a mold that grows on corn. Reasons for bile duct obstruction include tumors, gallstones, liver flukes and pancreatitis.
Symptoms of Canine Liver Disease
During the early stages of liver disease, the liver enlarges, resulting in symptoms common to other disorders: loss of appetite, vomiting and diarrhea, frequent thirst and urination. At this point, the dog can still recover and return to normal if the underlying condition can be successfully treated.
As liver disease progresses, however, liver cells die and the scar tissue replacing them is hard and rubbery. Once the disease reaches this stage, called cirrhosis, it is not reversible and the dog's condition is terminal. Eventually, when about 80 percent of the liver is dysfunctional, the condition is known as liver failure. The symptoms of liver failure are more specific than the symptoms of early liver disease. These include:
- Jaundice
- Spontaneous bleeding
- Hepatic encephalopathy
- Ascites, accumulation of fluid in the abdomen
- Edema of the lower limbs
In dogs, jaundice is detected as a yellowing of the whites of the eyes, the inside of the ears, and the mucous membranes. Jaundice also causes the urine to darken to a deep brown. Hepatic encephalopathy, which affects the brain, may cause the dog to become weak, disoriented, mentally dull or to behave oddly in other respects. Once the encephalopathy is advanced, the dog will experience seizures and eventually become comatose. Spontaneous bleeding may show up as bruises, blood in the urine, gastrointestinal ulcers, or tiny blood spots on the gums.
Diagnosis of Canine Liver Disease
Preliminary tests for canine liver disease include: blood tests and ultrasound or CT scans. If these tests lead to a suspicion of liver disease, a liver biopsy will most likely be performed, since this is the only definitive diagnostic test for liver disease.
Treatment of Canine Liver Disease
If treatment is begun promptly and not too much liver damage has occurred, early stages of canine liver disease can be successfully treated. Infectious diseases can be treated with medications. The negative effects of toxic medications or plants can be reversed if discovered early. In the case of bile duct obstructions, these can often be surgically removed.
Some treatment of canine liver disease involves attempting to prevent serious complications, like spontaneous bleeding and encephalopathy. Dogs may be prescribed a special diet low in protein and have their blood levels carefully monitored for ammonia, electrolytes and blood-clotting factors. Canine antacids may also be administered to prevent gastrointestinal ulcers. Some dietary supplements, such as milk thistle and SAM-e, may also be prescribed since these have been shown to help return the liver to normal function.