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)
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)
Serum bile acids
Blood clotting profile
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
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.