Inflammatory Liver Disease of Dogs and Cats:
Canine chronic active hepatitis and feline cholangiohepatitis
The liver is a large organ located in the abdominal cavity, and it performs more than 500 functions. Some important functions of the liver are:
· To process all of the blood coming from the stomach and intestines à thus, the liver plays a major role in the digestion, absorption, and assimilation of nutrients
· To produce bile that helps the body digest and absorb fats, as well as eliminate metabolic waste products from the body
· To regulate the production of amino acids, the building blocks of muscle
· To manufacture proteins for the immune system to protect the body from infection
· To clear the blood of toxic substances and drugs
· To help control blood clotting
· To store sugar for later use as energy
Dogs and cats can develop inflammation of the liver, significantly impairing any and/or all of these functions. This will make you pets feel very ill, and if left untreated could damage and/or destroy the liver. Inflammatory liver disease of dogs is called chronic active hepatitis (CAH). Inflammatory liver disease of cats is called cholangiohepatitis (CH).
Causes of liver inflammation
There are many causes of liver inflammation. The most common cause of liver inflammation is an attack of the liver by the immune system. For some reason as yet undiscovered by veterinary scientists, the immune system comes to perceive the liver as abnormal or foreign, and thus subsequently targets the liver for an immune “attack.” In cats, other organs, including the gastrointestinal tract and/or pancreas may “attacked” as well.
Hereditary predisposition to inflammatory liver problems is common in several breeds of dogs, including Doberman Pinschers, Cocker Spaniels, and certain terrier breeds (i.e. Bedlington terriers, Skye terriers, West Highland White terriers).
Toxins and/or drugs may also cause liver inflammation. For example, some types of wild mushrooms are very toxic to the liver. Medicines commonly used to prevent heartworm infection and seizures, as well as some types of antibiotics may also potentially harm the liver. Copper, a normal element contained in foods, may accumulate to toxic levels in the liver of some dogs, subsequently causing inflammation.
Infections by bacteria, parasites, and/or viruses may also cause liver inflammation in dogs and cats.
Symptoms of liver inflammation
One of the first signs of a liver problem may be an abnormal blood test when performed for routine screening on a well animal. Often the blood is tested prior to general anesthesia for a dental cleaning or during an annual wellness exam. At these times, symptoms of liver disease are not present yet because the liver is a very large organ with an extraordinary reserve capacity à it will still function normally at this early stage of the inflammation!
As liver disease progresses, chronic inflammation causes normal liver cells to be replaced by scar tissue. The presence of scar tissue directly interferes with the many jobs the liver performs, and therefore the liver can no longer function normally. Thus, symptoms of a liver problem become evident, as the animal no longer feels well.
Common symptoms of liver disease at a later stage include poor appetite, lethargy, weakness, vomiting, diarrhea, excessive thirst and urination, weight loss, and possibly jaundice (aka: a yellow tint to the skin and/or “whites of the eyes”).
Diagnosis of liver inflammation
Inflammatory problems of the liver are diagnosed by complete evaluation of a pet’s medication history, physical examination findings, blood and urine tests, abdominal ultrasound examination results, and liver biopsy/culture results. In dogs, a sample of liver will be evaluated for copper content as well.
A biopsy of the liver (evaluation of liver tissue by a specially trained veterinary pathologist) is the only way to diagnosis the specific liver disease present. As there are many different types of liver diseases that may cause the identical symptoms, accurate diagnosis is essential to reliably determine the best treatment for your pet, as well as to predict the most likely outcome (prognosis).
Treatment of inflammatory liver diseases
If toxins or medicines may have played a role in the development of liver disease in a dog or cat, the first steps are to stop administering these drugs and eliminate exposure to the toxin(s).
The cornerstone of therapy for most cases of inflammatory liver disease is the administration of medicine to reduce inflammation (anti-inflammatory medicines) and to suppress the immune attack of the liver.
The goals of additional therapy may include:
· Preventing scar tissue formation
· Promoting the flow of bile
· Protecting the liver, and helping it recover from injury
· Treating/Preventing infection
· Treating/Preventing stomach and/or intestinal ulcers
· Promoting normal blood clotting
· Eliminating copper from the liver
· Minimizing the accumulation of toxic waste products in the blood
· Preventing the buildup of fluid in abnormal body spaces
Nutritional support is an essential component of the treatment of dogs and cats with liver disease. Nutritional support may involve the use of special medicines to prevent nausea and/or vomiting, thereby enhancing appetite. Special diets easily digested by the liver may also be administered via temporary supplemental feeding tubes.
Prognosis of inflammatory liver disease
The outcome of dogs and cats with inflammation of the liver is variable, and directly related to the degree of inflammation and presence/absence of scar tissue. With minimal scarring, an appropriately treated pet with an inflamed liver may recover very well. This is the reason why early intervention is so important. The prognosis for an animal with a severely scarred liver and minimal normal liver is guarded to poor. This stage of liver inflammation is called cirrhosis.