Hepatitis In Dogs And Cats
Ron Hines DVM PhD
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Hepatitis means inflammation of the liver. Your pet's liver is a very complex organ that processes nutrients soon after they are absorbed through it's intestines. This makes it the first organ to come in contact with toxins and harmful products absorbed from your pet’s foods.
The liver plays a major role in metabolism, detoxification, energy storage and blood protein synthesis. It also produces bile, which aids in digestion. Your pet's liver has a very large reserve capacity - so it has to be severely damaged before any signs of illness will become apparent to you.
The following information relates to some of the more common causes of hepatitis in dogs and cats – there are many more, less- frequent, causes that I do not discuss here.
How Is Liver Disease Diagnosed In My Pet?
Until liver problems are quite advanced, the signs of the disease are rather vague and non-specific. The key to diagnosis is measuring the level of Liver enzymes that circulate in your pet’s blood. The most commonly elevated enzyme is ALT (Alanine Aminotranferase or SGPT). Elevated ALT tells your veterinarian that your pet has hepatitis but it does not tell what kind of hepatitis it is. Other enzymes that are often elevated in hepatitis are AST (Aspartate Transaminase SGOT) , GPT(Glutamate Pyruvate Transaminase), and alkaline phosphatase. A metabolite called bilirubin may also be elevated and blood albumin may be low. You can read the normal values for these tests here.
None of these test will tell your veterinarian what type of hepatitis your pet has or what caused it. To do that usually requires a biopsy of your pet’s liver. Using an ultrasound apparatus as a guide, the veterinarian will extract a small snippet of liver tissue using a specially designed needle. This is sent to a veterinary pathologist who will tell your veterinarian the type of hepatitis present, how severe it is and, perhaps, what caused it.
Infectious Canine Hepatitis Of Dogs (ICH, CAV-1)
This disease is caused by a virus. It is part of a group called adenovirus (CAV-1). This disease is not infectious to people or cats, but foxes, wolves and bears also catch and carry it. Dogs catch this disease by inhaling or eating the virus that is present in the urine, nasal and eye secretions of other infected dogs. Dogs can carry and pass on the virus for up to a year after recovering. Canine Adenovirus is part of the vaccine combinations your puppy receives when it is 12 -16 weeks old. Although the virus in the vaccine is Canine Adenovirus 2, it protects against type 1 as well. After receiving this vaccination at 12 and 14 weeks of age, your dog will be immune to CAV-1and CAV-2 for many years - probably for life. So booster vaccinations are not needed. Because of the effectiveness of this vaccine, Canine Infectious Hepatitis has become very rare in dogs in the United States.
After entering the blood stream, this virus attacks the cells of the liver, eyes, kidneys and the inner linings of blood vessels throughout the body. Most cases of CAV-1 are not serious. Many dogs have little or no symptoms after they are infected. In some dogs, only a cough develops. In this mild form, dogs simply loose their appetite, or are mopy and run a low fever for a few days. One or two weeks later, a few develop a temporary bluish discoloration of the cornea of the eye called “blue eye”.
All these dogs that recover from ICH are immune to the disease for the rest of their lives. A few puppies, , do become severely ill with infectious canine hepatitis. They can develop liver disease, internal bleeding, tonsillitis, and inflammation of the mouth and eyes. This can lead to shock and death.
After the virus gains entry to the dog, it localizes in the cervical lymph nodes and tonsils before traveling throughout the body. It takes approximately five days for infection to become apparent to the owners. By that time symptoms relate to virus in the liver, eyes, kidneys brain and lungs. Infected dogs shed the virus in their stool, saliva and urine. Over the next two weeks, the dog either dies from the disease or goes on to develop chronic hepatitis and cirrhosis of the liver. A few dogs develop chronic kidney disease (pyelonephritis), glaucoma or circulatory abnormalities (vasculitis, disseminated intravascular coagulation).
Once a dog has become infected with CAV-1 there is no treatment that will destroy the virus. The best one can do is to support the dog with good nursing care, intravenous fluids and medicines to lighten the workload on the liver. Antibiotics are also included in treatment to prevent additional infections.
Chronic Active Hepatitis (CAH):
This disease is sometimes called Chronic Canine Inflammatory Hepatic Disease. Chronic active hepatitis is more common in dogs than in cats. It can occur in any breed dog, male or female, and at any age, although most or the pets are middle-aged or older. The fact that is chronic means that the disease has been going on for weeks or months as opposed to acute hepatitis that comes on suddenly and then ceases. A pet with this problem is in Liver Failure.
Unfortunately full recovery is more likely after an acute hepatitis rather than the chronic condition. The term active means that liver cells are continually becoming inflamed and dying.
In CAH, continuous liver inflammation and cell death eventually lead to the replacement of the normal liver tissue with scar tissue. This is called cirrhosis. In most cases the exact cause of your pet's problem will remain unknown.
Certain breeds are predisposed to Chronic Active Hepatitis, these include Bedlington Terriers, Doberman Pinschers, Skye Terriers, Standard Poodles, Cocker Spaniels and West Highland White Terriers. In many of these cases, copper is found in excessive quantities in the dog’s liver. Other diseases that can lead to chronic active hepatitis are infectious canine hepatitis, leptospirosis, autoimmune disease and drug and chemical toxicities. Aflatoxins found in moldy grain – especially corn – can cause this disease. High quality dog foods test the grains they use for this toxin. You can read about some of the problems associated with these high-corn-content products here.
A recent study of chronic hepatitis in English springer spaniels in the UK found that it occurred at a younger age in that breed and with increased frequency in female dogs. No infectious cause could be found and the authors suggest that, perhaps, many cases of chronic hepatitis in dogs are a form of autoimmune disease. (ref)
What Are The Signs of Chronic Active Hepatitis?
Symptoms of chronic active hepatitis are quite variable because the liver does so many things. The most common signs are increased lethargy, loss of appetite and diarrhea. Pets often drink and urinate more. As the disease progresses, many cases develop a swollen abdomen that is filled with fluid (ascites) and yellowish (icteric, jaundiced) gums, eyes and skin. In some cases the disease attacks the nervous system and the dogs become blind and obtuse. This can progress to seizures, coma and death.
How is Chronic Active Hepatitis Diagnosed?
Diagnosis relies on blood chemistry results that show an increase in the level of hepatic enzymes and on biopsies of the liver. Physical examination of the dog can suggest the disease when jaundice is present. Dogs with chronic active hepatitis have smaller than normal livers. This can sometimes be seen on x-rays and ultrasound images of your pet. The texture of the liver with serious cirrhosis also changes. This is quite visible using these imaging techniques.
Can My Pet Be Helped?
Copper-Associated Chronic Hepatitis of West Highland White and Bedlington Terriers
Both these breeds sometimes inherit a defect in the metabolism of copper within their liver which causes a disease called copper-associated chronic hepatitis (CACH).
of the dogs that develop this problem become depressed and jaundice.
When it occurs in Bedlington terriers, they may also become severely
anemic and pass red urine. If they survive this crisis, they suffer
periodic bouts of hepatitis - particularly when stressed. Blood
tests show elevations in all the enzymes associated with hepatitis.
In the form seen in Westies, liver levels of copper build up to toxic level by six months of age and then sometimes decline and the overall concentration of copper in the liver is lower than in Bedlington terriers. Westies do not appear to suffer the hemolytic anemia that is common in Bedlington terriers with this disease.
Treatment in both breeds consists of a low copper diet and drugs that bind and lock up copper (chelating agents), vitamin C to help flush copper out through their urine and zinc acetate to block its absorption.
We see two types of Bedlington Terriers with this condition. The first are young dogs less than six years of age that suddenly develop liver failure. Most of these dogs pass away quickly in spite of intensive treatment. A few do recover but are plagued with liver problems for the rest of their lives.
The second group are older dogs that develop a slower, less severe form of the disease. They sicken very gradually and loose weight but the can live a long time. West Highland Terriers that develop this disease tend to have lower levels of copper in their livers and a less severe form of the disease. We estimate that 25% of Bedlington terriers suffer from this disorder and half the rest carry the genetic code for the defect but do not become ill. This is because two defective genes must be present for the disease to appear. These dogs can, however pass the disease on to their offspring.
In these pets copper accumulates within the cells of the liver due to the presence of an abnormal binding protein. These dog’s failure to excrete toxic copper through their bile slowly leads to hepatitis or cirrhosis of the liver. Clinical signs include enlarged liver, vomiting, depression, lack of appetite, jaundice, hemolytic anemia and hemoglobin in the urine. Treatment includes feeding diets low in copper and administering compounds that lower body copper stores. One of these compounds, D-penicillamine, binds with copper causing it to be voided in the urine. Another compound, trientine hydrochloride, decreases the amount of copper absorbed through the intestine. Prednisone anti-inflammatory treatment is also often helpful. Ursodeoxycholic acid (ursodiol; Actigall or Urso) is another anti-inflammatory and bile facilitating drug that has been helpful. S-adenosylmethionine (SAMe) is an antioxidant compound that appears to help some of these dogs. Milk thistle herb is yet another compound used to treat liver disease. It was thought that it’s active ingredients, which include antioxidants, might protect liver cells and facilitate liver repair (unfortunately, the only recent scientific study of milk thistle's "active" ingredient, silymarin, found it of no value in humans with one form of chronic hepatitis ref. Silymarin is one of the two "active" ingredients in Denamarin). Some veterinarians suggest these dogs receive vitamin E to protect against oxidative damage to liver cells. Dogs with this condition should not be bred, as they will pass on the disease through their genes.
Hepatitis Of Unknown Origin: Hepatitis of unknown origin or idiopathic or periportal hepatitis sometimes occurs in dogs. It is most commonly seen in middle aged dogs. All breeds and both sexes are susceptible. Signs include vomiting, diarrhea, weight loss, jaundice, ascites, depression and weakness as well as increased thirst and urination. Lab work shows an increase in the enzymes ALT and AP as well as increases in bilirubin, bile acids and globulin and a decrease in blood albumin and red blood cells. We treat this disease with supportive care, antibiotics, low-protein diets and sometimes immunosuppressants. How the disease progresses or resolves depends on the amount of functional liver tissue that can be saved.
Chronic hepatitis of Doberman Pinschers:
This is s a perplexing disease. Some of these cases suggest copper storage disease similar to West Highland and Bedlington Terriers but we are uncertain if excessive copper causes the condition or if the disease simply causes excess copper to be stored in the liver. Female dogs are more commonly affected than males. This disease can occur at any age. Signs include weight loss, diarrhea, jaundice, vomiting and drinking and urinating excessively. Dogs may also be disoriented due to increased blood ammonia and they may bleed excessively due to lood clotting defects. Liver enzymes, bilirubin, blood ammonia and serum bile acids are usually elevated. Ultrasound studies will reveal a shrunken liver. Treatment for this disease includes supportive care, anti-inflammatory drugs and azathioprine and ursodeoxycholic acid. Chances for a long life after this disease has been diagnosed are quite poor.
Hepatic Lipidosis in Cats: This disease occurs in cats that will not eat for a variety of health reasons. Cats that are affected were often overweight. These cats may have stopped eating because of a change made in their diets or because of a stressful situation at home such as moving, kenneling or health problems in their owners. Secondary hepatic lipidosis also occurs in cats that suffer from diabetes, intestinal disease, pancreatitis or any other serious systemic disease. No mater what the cause, all cats develop an over-accumulation of triglycerides (fat) within their liver which blocks normal liver activity. Signs of this disease include weight loss, vomiting diarrhea, listlessness, drooling and jaundice. Laboratory tests reveal elevated liver enzymes and anemia. In treating this condition we try to address any underlying disease in order to get the cat to eat. Until this is done, cats need to be tube-feed energy-rich, high caloric foods.Inflammation Of The Biliary System In Cats: This condition is common in cats but rare in dogs. Suppuration is the accumulation of white blood cells called neutrophils in an organ. In the suppurative form (called Suppurative Cholangitis or Cholangiohepatitis) bacterial, fungal or protozoal infection of the liver’s system of ducts that transport bile result in the diseases. In the non-suppurative or lymphocytic form of the disease, blood cells called lymphocytes and plasmacytes accumulate around inflamed bile ducts. In biliary cirrhosis fibrous tissues surround and occlude the biliary system. A similar condition, lymphocytic portal hepatitis, is an inflammatory condition that is probably an underlying autoimmune disease. You can read more about these chronic inflammatory conditions of cats here. Hepatitis Due to Feline Infectious Peritonitis Of Cats:
Feline infectious peritonitis or FIP is a deadly disease caused by a coronavirus that affects only cats. It causes inflammation of tissues throughout the body including the liver. Signs of this disease include weight loss, depression, abdominal fluid, jaundice, vomiting, diarrhea and fever. Mortality from this disease is a withering 100%. Affected cats are usually less than two years old or older than 10years. Many of these cats are also infected with the feline leukemia virus. Despite my intensive efforts cats with FIP do not live long.
Although many veterinary products for liver disease are sold, there are not many that have been scientifically proven to improve liver function in dogs and cats. Various special diets, nutritional supplements and "nutraceuticals" are marketed to improve dog and cat liver function; but most are based on theories that have have not been adequately confirmed. Humans also suffer from a number of inflammatory liver problems and liver problems in which the metabolism of fats and sugars within liver cells is impaired. The most common one is steatohepatitis (aka NASH) - related to obesity. As you know, that is a growing problem. When folks just can't seem to make the diet changes required to solve this problem, there have been encouraging results administering a synthetic bile acid, obeticholic acid. (ref) I do not know of any reports of it having been used in dogs or cats. But veterinarians often come to rely on discoveries that are the offspring of studies designed to help humans. Another compound under study is elafibranor. (ref) Let me know if you have additional information.