Chronic Active Hepatitis (CAH) in Dogs
Overview of Canine Chronic Active Hepatitis (CAH)
Chronic active hepatitis (CAH) is a chronic and progressive inflammation of the liver of dogs that leads eventually to the replacement of normal liver tissue with scar tissue. The disease is also called chronic canine inflammatory hepatic disease. In most cases, the cause of this disorder is never discovered. Potential causes include canine hepatitis virus (adenovirus I), leptospirosis, copper storage disease, drug toxicity, and genetic factors. Reactions on the part of the immune system to the liver inflammation may contribute to the progressive worsening of the disease.
All breeds of dogs can be affected, although the incidence is greater in the Bedlington terrier, West Highland white terrier, Doberman pinscher, cocker spaniel and Skye terrier. CAH usually occurs in middle-aged animals, and females appear to be at higher risk.
What to Watch For
- Loss of appetite (anorexia)
- Weight loss
- Excessive urinating and drinking (polyuria/polydipsia)
- Fluid in the abdominal cavity (ascites)
- Jaundice (yellow color to the skin)
- Increased bleeding tendencies
Diagnosis of Chronic Active Hepatitis in Dogs
- Complete blood count (CBC)
- Biochemical profile
- Serum bile acids
- Ammonia levels
- Blood clotting profile
- Abdominal X-rays
- Abdominal ultrasound
- Liver biopsy and culture/sensitivity
Treatment for Dogs with Chronic Active Hepatitis
- Hospitalization and support (fluid and electrolyte therapy) as needed for dehydration from severe vomiting, diarrhea and anorexia
- Treatment of any underlying disorders.
- Nutritional support and dietary management
- Antibiotic therapy
- Corticosteroids to decrease inflammation
- Drugs that stimulate the liver (choleretic) to enhance bile flow
- SAMe to improve liver metabolism
- Copper chelating drugs to bind and eliminate copper from the liver
- Diuretics to help decrease water retention in the body
- Vitamin K supplementation
- Antifibrotic agents to decrease scarring in the liver
Home Care and Prevention for Chronic Active Hepatitis
Administer all medications and recommended diets as directed by your veterinarian. Return for follow up examinations and biochemical evaluations.
There are no preventative measures for this disease, although performing biochemical profiles on dogs of susceptible breeds and initiating therapy in the asymptomatic stages will help slow the progression and development of serious clinical signs.
Information In-depth on Chronic Active Hepatitis in Dogs
Chronic active hepatitis (CAH) is a chronic and progressive inflammation of the liver of dogs that leads eventually to the replacement of normal liver tissue with scar tissue. The disease is also called canine chronic inflammatory hepatic disease. Affected individuals may be ill for weeks to months with signs of intermittent anorexia, weight loss, lethargy, excessive urinating and drinking, and jaundice. In the end stages of this disease when scarring of the liver is severe and the liver can no longer function properly, affected dogs may develop fluid accumulation in the abdomen and signs of hepatic encephalopathy. Hepatic encephalopathy is malfunction of the brain due to the accumulation of toxins that are ordinarily cleared from the blood stream by the liver.
There are several diseases/disorders that can appear similar to CAH. These include:
- Cancer in the liver, such as lymphosarcoma
- Hepatotoxins, which are chemicals or drugs that injure the liver and include certain drugs, heavy metals, certain chemical flea and tick dips and sprays
- Chronic hepatitis due to bacterial, fungal, protozoal or parasitic infections
- Chronic liver disease due to abnormal copper storage and accumulation in the liver
- Pancreatitis, an inflammation of the pancreas that often causes vomiting, lethargy, and inappetence
- Pancreatic cancer that blocks the biliary tract (bile duct system) causing similar symptoms.
- Intestinal inflammation, tumors or foreign bodies
- Other causes of jaundice
- Primary gallbladder diseases, such as stones, cancer, inflammation, or infection
- Other causes of abnormal clotting of the blood (bleeding disorders)
Diagnosis In-depth of Chronic Active Hepatitis in Dogs
The clinical signs associated with CAH are rather vague and nonspecific, so your veterinarian may not be able to make a presumptive diagnosis without performing certain diagnostic tests. A complete history and thorough physical examination are important initial steps to take. The following tests are then considered to rule out other disorders and to confirm a diagnosis of CAH:
- A complete blood count (CBC) may be within normal limits. It may also reveal a mild anemia, an elevation in white blood cell count, and a low circulation protein level.
- A biochemical profile usually reveals elevations in liver enzymes. Other abnormalities may be seen, such as an elevated bilirubin (evidence of jaundice), low circulating proteins, low blood sugar, low blood urea nitrogen, and low cholesterol. Electrolyte abnormalities such as low potassium, low chloride and high sodium levels are also common.
- A urinalysis helps assess the kidneys and level of hydration of the patient and may sometimes detect bilirubin in the urine.
- Serum bile acids are usually elevated, which denotes an inability of the liver to function normally. Measurement of bile acids may be performed in patients who have normal bilirubin levels.
- A clotting profile, as clotting disorders are common with chronic liver disease. In addition, biopsies of the liver become more dangerous if the blood cannot clot properly.
- Blood tests to detect abnormal ammonia levels in the blood may be useful, particularly if the animal is depressed, disoriented, and has seizures or other signs of hepatic encephalopathy.
- Abdominal radiographs (X-rays) may be within normal limits, although they may reveal fluid in the abdomen (ascites), enlarged liver (hepatomegaly) or small liver (microhepatica).
- Abdominal ultrasonography is recommended in most cases. It is very helpful in evaluating all of the abdominal organs, including the liver. It is equally important to rule out other disorders or diseases that may initially be difficult to differentiate from CAH. With the guidance of ultrasound, it is often possible to obtain a sample of the liver for evaluation and culture/sensitivity. A clotting profile should be performed first, and tissue should only obtained if the clotting parameters are within normal limits. Your veterinarian may refer your dog to a specialist in veterinary internal medicine or veterinary radiology to perform this procedure.
Your veterinarian may recommend additional tests to exclude or diagnose concurrent conditions and to confirm the diagnosis of CAH. These tests are not necessary in every dog, so are selected on a case-by-case basis:
- Laparoscopy is a procedure that allows visualization and sampling of abdominal structures via a small scope introduced into the abdomen through a tiny incision. It is more invasive than an ultrasound-guided biopsy, but it allows the veterinarian to look directly at the liver and its associated structures. It helps ensure that the biopsy is taken from an area of the liver that is clearly abnormal. It requires that the animal be placed under general anesthesia, and usually requires referral of the animal to a veterinary facility with the appropriate specialized instruments.
- Laparotomy is an abdominal exploratory surgery. It allows close inspection of the entire liver and other abdominal structures. It allows large biopsy samples to be obtained and may be indicated in cases where an biliary obstruction needs to be relieved and diverted. It also provides a mechanism for the removal of certain masses and tumors that may be responsible for the clinical signs.
Treatment In-depth for Dogs with Chronic Active Hepatitis
Goals in the treatment of CAH include eliminating any underlying cause; decreasing inflammation within the liver and providing an environment in which the liver can recover; controlling any complications; and attempting to stop progression of the disease. Patients with CAH may need to be hospitalized and treated aggressively. Depending on the stage of disease and clinical signs involved, outpatient therapy may or may not be sufficient. It is extremely important to have a diagnosis confirming CAH prior to treatment, as treating the symptoms is often ineffective.
- Eliminate or treat any underlying disorders if at all possible. Use antibiotics for bacterial infections. Stop the administration of all drugs that are cleared by the liver.
- The animal is hospitalized and intravenous fluid and electrolyte therapy is instituted as needed for dehydration or to correct electrolyte disturbances from severe vomiting and diarrhea.
- Intravenous nutrition may be started in malnourished dogs or dogs that cannot retain food due to vomiting.
- Dietary recommendations for dogs with liver disease include reducing the amounts of protein in the diet and changing to a higher quality of protein. A major dilemma in formulating these diets is that the animal is often malnourished, and it is vitally important to maintain body weight and muscle mass while minimizing the signs of liver failure. There are commercial prescription diets available that are designed to provide reduced levels of high quality protein, including Hill’s Prescription Diet L/D. Formulas are also available for making homemade diets.
- Choleretic drugs that enhance bile flow, such as ursodeoxycholic acid (Actigal®), may be tried. In addition to protecting liver cells from the local effects of bile acids, it also has anti-inflammatory properties.
- SAMe (Denosyl®) can be administered in an attempt to improve the metabolism of the liver. It is manufactured in the normal liver, but its production is often deficient in the diseased liver, so replacement therapy with SAMe may be beneficial.
- Corticosteroids, such as prednisone, may be administered when active inflammation is demonstrated on the liver biopsy. The administration of prednisone may make some of the clinical signs associated with CAH worse (such as retention of fluid in the abdomen, ulceration of the stomach and intestinal tract, bacterial infections), and the drug is somewhat hard on the liver itself. The use of prednisone must be decided on a case-by-case basis.
- When copper storage is involved in CAH, specific treatments that limit the accumulations of copper can be tried.
- Antifibrotic drugs, or drugs that decrease scarring in the liver, may be tried, especially when scarring is a prominent finding on the liver biopsy. The most common drug used to decrease scarring is colchicine.
- Fluid accumulation in the abdomen (ascites) may be treated with diuretics to facilitate removal of fluid. Such diuretics include spironolactone (Aldactone®) and furosemide (Salix®). Ascites due to low circulating blood protein levels may improve with the intravenous administration of plasma and other blood expansion products.
- Although drugs that alter the immune system have been used in the past to treat CAH, currently their use is reserved for those cases that do not respond to other therapies. The most common immune-modulating drug used in dogs with CAH is azathioprine.
- Gastrointestinal ulceration is a common complication of chronic liver disease. It may be prevented with drugs that decrease acid production by the stomach. Cimetidine (Tagamet®), famotidine (Pepcid®), ranitidine (Zantac®), and omeprazole (Prilosec®) can be used for this purpose.
- Coagulopathies are clotting disorders associated with liver disease and are treated with injectable vitamin K.
Follow-up for Dogs with Chronic Active Hepatitis
Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not improve rapidly. Administer all prescribed medications and diets as directed. Alert your veterinarian if you are experiencing problems treating your pet.
Initially blood tests are taken every few weeks to monitor response to therapy and the status of the liver. As the animal stabilizes, the testing frequency may be decreased to every 4 to 6 months.. In patients with ascites, monitor body weight on a daily basis. As fluid is lost from the body, the dog’s body weight will drop.
A second liver biopsy is often needed at some point to assess what is happening on a cellular level within the liver. This disease is very difficult to treat and is rarely cured. With consistent care and monitoring, the progression of the disease can sometimes be slowed, and the dog can be provided with a good quality of life. If the disease is ignored or if treatment and monitoring are inconsistent, then CAH often progresses to cirrhosis of the liver and end stage liver failure.