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What is Hepatitis?
Hepatitis is inflammation of the liver. It is a syndrome - a group of clinical signs or symptoms - rather than a specific disease, and it has many causes. Your dog can have immediate inflammation in their liver called acute hepatitis or long-term inflammation called chronic hepatitis. Chronic hepatitis (CH), also called chronic active hepatitis, can lead to scar tissue formation and cirrhosis in the liver. Cirrhosis is extensive, end-stage scar tissue. Some dogs with acute hepatitis progress to the chronic form.
Infectious Canine Hepatitis
One disease that causes chronic hepatitis is infectious canine hepatitis (ICH). ICH is caused by a virus but not the same as the Hepatitis A, B or C viruses that cause disease in humans; you and your family won’t get sick if your dog is infected. Similarly, The hepatitis viruses that cause human heptitis do not affect dogs. ICH is spread through animal feces, urine, saliva and objects. Since most dogs are vaccinated as puppies against ICH, it is considered a rare infection. However, outbreaks sometimes occur, mostly in dogs less than 1 year old or unvaccinated dogs. An infected dog may show signs of depression, fever, vomiting, diarrhea, and abdominal pain. Treatment involves supportive care such as fluids and medications to boost liver function; the latter may include SAMe, milk thistle, ursodiol, and vitamin E.
Aside from ICH, there are many other causes of hepatitis. Causes of acute hepatitis include toxins, drugs, viruses, bacteria (particularly leptospirosis) and fungi. On the other hand, chronic hepatitis is caused by bacteria, viruses, excess copper in the liver, drugs, and immune system issues. If a cause cannot be determined, this is referred to as idiopathic hepatitis and is the most common cause. Idiopathic means no cause can be found.
Age and Breed Predispositions
Any dog can have an acute episode of hepatitis. Chronic hepatitis, on the other hand, is most common in middle-aged to older dogs; most dogs diagnosed with chronic hepatitis are 4-10 years old.
Some breeds are suspected to have a genetic predisposition to CH, making them more likely to develop it. These include the Bedlington Terrier, Doberman pinscher, West Highland white terrier, Dalmatian, English springer spaniel, American and English cocker spaniels, Jack Russell terrier, standard poodle, Great Dane, Labrador retriever, and others. CH is also more common in females than males.
Dogs with acute hepatitis often have more severe signs than those with CH. Symptoms may include anorexia (lack of appetite), vomiting, diarrhea, dehydration, depression, fever, and jaundice (yellow discoloration of the eyes, gums, and skin), enlarged abdomen and weight loss. How serious your dog’s symptoms are depends on how much liver damage they have and this may vary from mild to severe. In severe cases, there are signs of bleeding and bruising. Bleeding can occur inside the body or through any opening of the body, such as the nose and mouth.
Dogs with chronic hepatitis often appear normal early on. It is often surprising how normal the dog appears, even with significant progressing disease. This is why it is a good idea to pay attention to elevations in the liver enzymes (particularly ALT), as there is a better chance of slowing down the disease the sooner it is detected and appropriate management begins. As the disease gets worse, common signs are poor appetite, vomiting, diarrhea, depression, increased thirst and urination, weakness, jaundice and weight loss. A small number of dogs have severe signs such as bleeding, incoordination, and behavior changes. Similar to acute hepatitis, bleeding can occur through any opening in the body.
Similar to many illnesses, a thorough history and physical examination from your veterinarian are crucial to making a diagnosis. Drug history and potential exposure to toxins are particularly important as these can cause significant liver damage. Some dogs with hepatitis have increased levels of liver enzymes that can be seen on lab work. These increases do not have to be large to be important; they may indicate liver damage but can also be caused by many different diseases.
Elevated liver values are a common abnormality, but they are often non-specific and can be confusing to pet owners. Not all cases of elevated liver enzymes indicate specific liver disease. The liver performs many functions and, in some cases, the liver enzymes may elevate due to problems elsewhere in the body, or simply due to age. It is a good idea to look into these sooner rather than later, especially if your dog is one of the breeds predisposed to hepatitis. They may be the only abnormality a dog with chronic hepatitis has at that time.
To add to the confusion, some dogs with hepatitis can have normal liver enzymes. This normalcy does not rule out chronic hepatitis: CH can be so severe in some dogs that there is little functioning liver tissue left to release enzymes, making test results look ‘normal.' If hepatitis is suspected, your veterinarian may recommend a serum bile acids test specifically to evaluate liver function. Another diagnostic test is an abdominal ultrasound. Abnormalities on these tests may strongly suggest hepatitis, but often do not pinpoint a cause. A liver biopsy is the most accurate way to make a diagnosis.
Treating a dog with acute hepatitis involves supportive therapy such as fluids, medications and antioxidants.
Treating chronic hepatitis has several goals: treat the underlying cause, reduce inflammation and scarring/cirrhosis, provide supportive care, and treat complications. This support may involve changing current medications, use of antibiotics, and medication meant to reduce excess copper. Steroids, and/or other immunosuppressive drugs, may be used to reduce inflammation if infection is not suspected. Supportive care works to boost liver function, while treating complications depends on the specific problems.
Your dog may benefit from specific dietary changes depending on their individual condition and the cause of their chronic hepatitis. Dogs whose chronic hepatitis is associated with excess copper in the liver should be fed diets reduced in copper. They can also have a zinc gluconate supplement added to their food which acts to reduce copper levels as well. Regardless of cause, dogs with chronic hepatitis may benefit from diets with restricted protein levels. Restricted protein diets are not always necessary however and are only considered if your dog has evidence of protein intolerance. Your veterinarian will work with you to determine if your dog needs to be on a protein restricted diet. Another important dietary factor to consider for a dog with CH is how tasty and nutritious the food is. Dogs with CH often do not want to or are reluctant to eat. It's important your pet's food is appetizing to them and has high levels of carbohydrates and moderate levels of fat to provide them with their necessary calories. There is evidence that fiber may benefit dogs with liver disease and is another factor to consider increasing in your dog's diet.
Your pet’s prognosis depends on the underlying cause of their hepatitis. In general, acute hepatitis has a better prognosis than the chronic form. If the liver is not too damaged, most dogs recover. Some, however, progress to chronic hepatitis.
According to one study, the average survival time with chronic hepatitis was two to three years, although individual results depend on the condition and response to treatment. Identification of the liver disease (via biopsies) is the best way to ensure the proper treatment. The prognosis is much worse if scarring and/or cirrhosis is extensive or blood clotting test results are abnormal. To ensure the health of your pet, it is important to not only treat hepatitis as soon as it is diagnosed, but also to look into abnormal test results such as elevated liver enzymes; these may be early signs of liver issues.