Goals of Treating Liver Disease
The liver is unique in that it has a large reserve capacity and more regenerative capability than almost any other organ. As a result, canine liver disease typically can be treated, or at least managed, if a diagnosis is made early. Treatment depends upon the underlying cause of the condition. The goals of treating liver disease are to eliminate harmful toxins (or minimize their detrimental effects on the liver), promote healing and regeneration of liver tissue, prevent or control complications of liver dysfunction, treat the underlying cause when possible and keep the dog as comfortable and stable as possible until sufficient liver function can be restored. Treatment options include prescription and over-the-counter medications, dietary supplements, lifestyle changes, supportive care, surgical procedures and a number of other possible therapies that the attending veterinarian will discuss with her patient’s owner.
Treatment protocols for dogs with liver disease vary based upon the cause of the condition. Acquired liver diseases in dogs are extremely diverse, especially chronic disorders which are collectively referred to as “chronic hepatitis.” Chronic hepatitis in dogs refers to a range of disorders that have similar historical features and clinical signs. Hepatitis can be familial (especially in Bedlington Terriers, Doberman Pinschers, West Highland White Terriers, Skye Terriers and Dalmatians), but it also can be caused by infection, ingestion of certain drugs or toxins or by unknown factors. Treatment options for dogs with liver disease may include some or all of the following approaches and often will be long-term.
Dietary adjustments are normally recommended to ensure that a dog with liver disease receives the caloric and nutrient intake necessary to support liver regeneration and to manage the effects of hepatic encephalopathy. So-called “liver diets” are commercially available but can also be homemade. They are designed to contain extremely digestible, high-quality but restricted levels of bioavailable protein, to reduce the metabolic demands on the liver. Protein restriction is important to reduce the levels of circulating ammonia, which comes from bacterial breakdown of protein in the gut. Non-meat protein sources, such as dairy products and eggs, generally are preferred in diets for dogs with liver disease. The attending veterinarian can recommend an appropriate diet, which might include carefully regulated portions of certain carbohydrates, vitamins, proteins, minerals and fats. Dietary sodium (salt) should be restricted in dogs that are retaining excess fluid in their abdomens due to liver disease. In addition to dietary changes, the veterinarian may suggest vitamin or other oral supplements that can promote liver regeneration and improve liver functioning, such as Vitamin E, Vitamin C, Vitamin K, zinc, S-adenosylmethionine (“SAM-e”), milk thistle (silybin) and/or Ursodiol.
Treatment of Copper-Related Hepatitis
For liver disorders associated with abnormal accumulation of copper, the amount of ingested copper must be minimized. There are several commercially available prescription diets, and/or diets that can be made at home, that contain restricted copper levels. The attending veterinarian may recommend supplementation with zinc or copper chelating agents, which help remove these elements from the bloodstream.
Drug therapy is warranted for many dogs with liver disease. Glucocorticoids (“steroids”) have been used to prolong survival times in dogs with liver disease due to their anti-inflammatory and immunosuppressive properties, although their use and appropriate dosage protocols are somewhat controversial. Azathioprine has been used to manage some of the adverse effects of steroid medications. However, azathioprine can contribute to bone marrow damage. Antibiotics are sometimes prescribed to combat bacterial infections, especially when hepatic abscesses are present. Other medications have been used to combat liver fibrosis, including colchicine. Studies of this anti-fibrotic agent in people with fibrotic liver disease show remarkable improvement in symptoms and survival rates. Some dogs have benefitted from its use as well, although reported side effects include diarrhea, vomiting and abdominal discomfort.
Other medications are available to relieve vomiting (emesis), gastrointestinal bleeding and gastric ulcers, if present. These currently include ranitidine, famotidine and omeprazole, sometimes in combination with sucralfate. Lactulose is commonly prescribed in cases of hepatic encephalopathy to increase the dog’s gastrointestinal tolerance of proteins. Lactulose is broken down by bacteria in the colon and traps ammonia molecules there, making them non-absorbable and therefore excreted in the dog’s feces. Lactulose also changes bacterial metabolism so that less ammonia is generated in the first place. If the dog has seizures associated with its liver disease, barbiturates such as phenobarbital may be recommended, although generally barbiturates are avoided in cases of liver disease.
Other medications will no doubt be developed over time to help treat the causes and consequences of liver disease. Drugs that require metabolism by the liver to become effective (or to be eliminated by the body) are normally avoided, and drugs are prescribed conservatively and in moderate doses in dogs with liver disorders. Protocols for medical management of canine liver disease are rapidly changing based on the results of scientific studies and drug trials.
Sometimes, liver disorders are treated only with supportive care, although normally supportive care accompanies other treatment methods. Intravenous or subcutaneous fluids may be given to resolve dehydration and restore proper electrolyte balance. Antacids or other medications for taxing symptoms like vomiting and diarrhea can be given. Of course, a safe, calm, quiet, temperature-regulated environment, a healthy diet and free access to fresh water are all essential.
Blood transfusions may be appropriate in dogs that have severe bleeding disorders associated with clotting and coagulation abnormalities caused by liver disease. Fresh whole blood, fresh packed red blood cells or fresh frozen plasma typically are used, because stored blood products contain high ammonia concentrations which are undesirable in most cases of liver disease. High ammonia concentrations contribute to the behavioral and neurological signs associated with hepatic encephalopathy.
When a dog has an identifiable liver or gall bladder mass, the treatment of choice usually is surgical removal. Internal hemmorhage is the most common complication of these surgeries, and fresh blood products should be available in case transfusion is necessary before, during or after surgery. Dogs with liver disease are anesthetic risks, because most anesthetic agents are processed by the liver. Chemotherapy and radiation therapy can be used for some forms of liver cancer. Unfortunately, treatment options are very limited for those cancers affecting more than one lobe of the liver, and for those that are metastatic.
Newer Treatment Options in Development
New treatment options are being explored for companion animals with liver disease - especially for those with cancer (neoplasia). These include intra-arterial chemotherapy, trans-arterial chemoembolization, percutaneous ethanol injections, microwave coagulation and various immunotherapeutic strategies. While these potential therapies are beyond the scope of this article, owners of dogs with liver disease may want to discuss them with their veterinarian to determine the most current status of their development, availability and cost.
The liver is a remarkably complex organ that can malfunction and yet recover in multiple ways. Specific treatment protocols and an accurate prognosis depend almost entirely upon the cause and extent of liver dysfunction. Only a veterinarian can assess which treatment methods are best in any given case of canine liver disease and provide an accurate prognosis for the patient in question.