The largest organ in both the human and canine body, the liver is located in the abdominal cavity adjacent to and behind the stomach. It sustains a number of biologic processes in the animal's body that are vital to survival. Any dysfunction of these processes, whether by infection, injury or ingestion of toxins, can cause liver disease in dogs.
The liver metabolizes carbohydrates and fats from the dog's food–turning glucose into energy, manufacturing cholesterol and regulating fatty acids. It produces numerous enzymes that synthesize into proteins and carry out other body functions. The liver also processes waste from the dog's body, detoxifying the blood of drugs and toxins.
Inflammation is the first stage of liver disease; it usually means that the liver is trying to heal itself from infection or injury. The inflammation might be palpable upon veterinary examination or show up on a radiograph, but it is usually not painful to the dog. At this point, liver disease can usually be treated successfully with medication and diet change.
The second stage is fibrosis. The inflamed liver will begin to scar and harden and replace healthy tissue with scar tissue. As this stage progresses, blood flow through the dog's liver will be compromised, and a blood screen will begin to show abnormalities. Treatment started now might still be successful with the dog's liver healing over time.
The third stage is cirrhosis. The liver is so seriously scarred that it can no longer heal itself, and damage is irreversible. It is at this point, usually when 75 percent to 80 percent of the liver has been compromised, that a diseased dog might begin to show symptoms. Veterinary treatment started now is usually intended to prevent the disease from getting worse and protect whatever healthy tissue is left.
Liver failure is the final stage. This means the dog's liver is no longer functioning–a life-threatening condition. Symptoms will worsen, and veterinary treatment now becomes palliative, designed to alleviate symptoms and make the dog more comfortable. At this point, the animal might become comatose and die.
Symptoms usually start gradually and progress through time. They might initially show signs of vomiting, diarrhea or constipation. Animals might become depressed and show a gradual weight loss with an unwillingness to eat. Fluid can accumulate in the abdomen, and the belly might become swollen and painful. The dog's skin and mucous membranes might become yellow (jaundice), and they might start producing orange urine and pale feces. In the final stages of the disease, the animal might exhibit neurological symptoms, including pacing, going in circles and seizures.
Treatment of canine liver disease usually includes intravenous fluids with additives such as electrolytes, glucose, potassium and vitamin K. Veterinarians might recommend antibiotics to treat any underlying infection and a change in diet to a dog food high in proteins and complex carbohydrates. Dogs might receive supplements of vitamin K, water-soluble vitamin E and a multivitamin.
At some point, the disease might become incurable, and the issue of euthanasia will have to be examined. Consulting a veterinarian at this point should give caregivers all the information they need to make a well thought out decision.