Hepatitis in dogs is a medical condition that is mainly characterized and identified by continuous inflammation of a dog’s liver. The infection is related to a buildup of inflammatory cells within the liver when there has been ongoing scarring or the appearance of an unreasonable amount of fibrous tissue in the liver.
Together, these conditions can lead to a malfunctioning or decreased functioning of your dog's liver. If the condition is not identified early on and is left to develop over time, it can become very serious. As the condition worsens, it can lead to permanent liver damage and possibly liver failure.
Survival times in dogs with hepatitis vary on many factors (1, 2, 3, 4). A number of studies observing dogs that were treated with different medications and diets established mean survival time to be 561 ± 268 days. Dogs with cirrhosis, the latest stage of liver damage, had the shortest mean survival time of 23 ± 23 days.
Causes of Hepatitis in Dogs
What causes hepatitis in dogs will vary, and it's not limited to one or two situations. Hepatitis may be caused by bacterial infections, gallstones, cysts, liver cancer, ingestion of toxic substances, drugs, diabetes, Cushing’s disease, leptospirosis, injuries to the liver, or many other endocrine diseases.
There is little evidence of viral causes for chronic hepatitis (5, 6, 7). Some bacteria has been shown to cause hepatitis in dogs, particularly Bacillus piliformis, Helicobacter canis, and Bartonella spp, as well as Ehrlichia canis, but more compelling evidence is needed (8, 9, 10, 11).
Leishmaniasis and many other systemic diseases, including Neospora, toxoplasmosis, Sarcocystis, histoplasmosis, Mycobacterium, shistosomiasis, visceral larva migrans may also be the cause of canine hepatitis (12, 13, 14, 15, 16, 17).
Studies show that several drugs used to treat other conditions in dogs may damage the liver and cause hepatitis. For example, phenobarbital, primidone, phenytoin and lomustine were found to cause chronic hepatitis in dogs (18, 19, 20, 21). More research found that acute hepatitis in dogs may be caused by drugs and toxins like carprofen, oxidbendazole, amiodarone, aflatoxin, and cycasin (22, 23, 24, 25, 26).
Copper-associated hepatitis may occur in any dog breed, but some breeds are more predisposed to develop it: Bedlington Terrier, Dalmatian, Labrador Retriever, Doberman Pinscher, and West Highland White Terrier (30, 31, 32, 33, 34, 35).
These breeds are predisposed to hepatitis due to their genetics, which greatly increases a dog’s risk of developing or contracting hepatitis during their lifetime. Nowadays, how likely a dog is to develop hepatitis later in life can be assessed with a dog DNA test.
It's not related to a dog's specific age, and can happen at any point in your pet's life.
Dog Food as Potential Cause of Hepatitis in Dogs
Some studies observed that cases of hepatitis, particularly chronic hepatitis in dogs, began to increase in the late 1990s. The increasing frequency of liver damage in dogs has been associated with pet food manufacturers supplementing commercial dog foods with copper, increasing the amount of bio-available copper in a dog's diet (36, 37, 38, 39).
There is some evidence that dietary guidelines from National Research Council (NRC) and Association of American Feed Control Officials (AAFCO), paired with addition of more bio-available copper chelate premixes in commercial dry pet foods, are directly related to the accumulation of dangerous levels of copper in dogs (40, 41, 42, 43, 44).
The above linked studies also found how concentration of copper levels in many dog foods were exceeding NRC dietary guidelines.
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How Hepatitis Affects Your Dog's Liver
The liver is responsible for completing many different tasks within a dog's body, making it one of the most essential and necessary organs. It produces enzymes that support digestion and metabolize proteins, fats, and carbohydrates that enter the body. It stores vitamins and nutrients critical for a dog's well-being, and breaks down the toxins, all while eliminating the waste from the animal's body.
A dog's liver is large enough to restore balance to itself; if one portion is not capable of completing its job, another part will take over. It is even capable of recreating its tissue when in the right environment and under the right necessary circumstances.
When a dog suffers from hepatitis, the disease attacks the liver in a way that it cannot easily recover from. It’s breaking down the liver over time, making it less and less effective, eventually rendering it useless. As the dog continues to suffer, their condition will worsen, leaving their liver in a state that may not be repairable.
Types of Hepatitis in Dogs
There are three types of hepatitis in dogs, each with their origins and causes: metabolic hepatitis, autoimmune hepatitis and infectious hepatitis. They all share many of the same symptoms, and all three types do significant damage to your pet's liver.
Metabolic hepatitis is when the liver is inflammatory due to the dog being exposed to a toxic or chemical element, or drugs that have damaged the liver over a period of time. The damage is done to cells directly or by changing their structure or metabolism processes. For this type, symptoms will occur once the damage to the liver is severe.
Autoimmune hepatitis is when the liver inflammation is caused by the dog’s immune system. This happens when your dog's immune system attacks the liver cells because it mistakes them for pathogens rather than being part of the body. Autoimmune hepatitis is also known as autoimmune liver disease and is a chronic version of hepatitis.
Infectious hepatitis is most common in puppies. It is when the liver inflammation is caused by canine adenovirus type I, an acute viral disease. It's capable of spreading through urine, contaminated water, and contaminated objects.
Hepatitis in dogs will also progress from stage to stage, such as from acute hepatitis, to chronic hepatitis, to liver cirrhosis. How the condition progresses depends on a very large number of factors (46).
Infectious Hepatitis in Dogs
Infectious hepatitis is generally the most harmful form of hepatitis because it affects mainly dogs that are one year of age or younger (47). Typically, it's easily identifiable and preventable, but can sometimes be presented in a hyperacute form. When that happens, the condition becomes fatal.
Thankfully, as this type of hepatitis is developed by a virus, a vaccine has been created and is highly effective. It is critical that all puppies be vaccinated for infectious hepatitis. If they are not vaccinated, they pose a risk to other dogs and other puppies of the litter. They are also more likely to develop the hyperacute form of hepatitis and die.
Symptoms of Hepatitis in Dogs
As your dog's condition worsens, they will likely experience a range of symptoms. Not all dogs will experience the same symptoms and may only suffer through a select few. Even as the type of hepatitis differs, the symptoms stay relatively within the same limitations.
Vomiting/Diarrhea – Some of the very first indicators that the dog may have hepatitis are vomiting and diarrhea. As the liver becomes less effective in completing its functions and becomes incapable of completing specific tasks, that's when vomiting and diarrhea will occur.
Lethargy – As the dog suffers from a lack of nutrients due to a decreased appetite, they will become more lethargic, slow and weak.
Decreased Appetite – The dog’s liver is malfunctioning, causing problems with their ability to digest and metabolize proteins, fats, and carbs. Dogs often portray this externally as a lack of appetite.
Weight Loss – A symptom also caused by the lack of appetite, dogs will gradually begin to lose weight. In puppies, the weight loss may be drastic; the pup should be taken to the vet immediately.
Frequent Urination/Excessive Thirst – a decreased appetite and an upset stomach (vomiting and diarrhea) can contribute to excessive thirst. It is not unusual for dogs to drink more than they normally do. With the increase in liquids, they release more than average. Fluid intake is a crucial sign of when something is wrong with your pet.
Swelling of the Abdomen – As a side effect of the enlarging of the liver due to inflammation and a buildup of fluid in the abdomen, the dog's entire stomach becomes visibly swollen.
Jaundice – As the infection progresses, it can induce canine jaundice. This can lead to a dog’s gums, eyes, and sometimes their skin to turn yellowish. This is another obvious sign of hepatitis in dogs that pet owners will notice early on.
Neurological and Nervous System – These are symptoms that are experienced by the dog after the disease has progressed. The neurological symptoms can include disorientation, depression, aggression, and, in serious cases, blindness. Nervous system signs are mainly seizures and possibly a coma. The coma is rare in dogs, but has been known to occur in certain cases.
Jaundice and ascites are more rare in dogs with hepatitis, and studies show them to occur in about 33% of dogs. Bleeding tendencies occur in about 7% of dogs. Animals with a late stage of chronic hepatitis or liver cirrhosis will be more likely to have ascites as well as gastrointestinal bleeding (52, 53, 54, 55).
Other symptoms may be present within the dog and should be accompanied by one or more of the symptoms above. If your dog is experiencing any of these, take them to the vet immediately to make sure that they do not have and are not developing hepatitis.
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What to Do If You Believe Your Dog Has Hepatitis
If the dog is experiencing any of the common symptoms, or you suspect your pet to be developing hepatitis, schedule an appointment with the vet as soon as possible.
Once at the vet, they will usually initiate a blood test and urinalysis to verify and determine the overall health of the dog’s liver. In some cases, the vet may use an ultrasound to help with measuring the size of the liver and check for any cysts, gallstones, or the presence of cancerous cells (57). Depending on the results of the previous tests, a liver biopsy may be requested (58). This will help in providing a conclusive diagnosis of dog hepatitis.
While waiting for the results of the test, the vet may prescribe certain medications or antibiotics for your pooch. Long-term treatments with prednisolone or azathioprine have been shown to have good results and successfully treating the condition (59, 60).
These are meant to control the symptoms the animal is experiencing, and early treatment increases the success rate. The veterinarian may also begin fluid therapy to prevent your dog from becoming dehydrated.
How to Treat Hepatitis in Dogs
The recommended treatment for hepatitis will vary from dog to dog, and from case to case. There is a wide scope of possible vet-prescribed treatments that focus primarily on symptom treatment rather than eradication of the infection. It is also determined by the type of hepatitis a dog has been diagnosed with.
If the dog is diagnosed with acute hepatitis, they have a good chance of recovering quickly. On the other hand, one out of three dogs suffering from acute hepatitis will develop chronic hepatitis. Owners are often unaware of its development, as signs of chronic hepatitis take time to show. Most vets will recommend having a liver biopsy completed four to six weeks after being diagnosed with acute hepatitis.
There are also cause-specific treatments for hepatitis in dogs. For example, for drug and toxin induced hepatitis, antioxidant treatment will be recommended, with possible inclusion of anti‐inflammatory dosage of corticosteroids (61). Supplements like milk thistle may be used, although their efficacy still needs more compelling evidence.
For dogs with hepatitis due to extra copper in their diet, treatment involving complete removal of copper from the liver, and lifelong restriction of it in the dog's diet is recommended (62, 63). Zinc may be added to the diet to restrict copper absorption in a dog (64, 65).
As of right now, there is no complete cure for chronic hepatitis in dogs (66). This condition can then lead to cirrhosis in a dog (67). Often, pets are diagnosed only after the disease has progressed and developed already, which is why it is essential that the symptoms are easily recognized and known. When the symptoms are known, the diagnosis can happen much quicker.
When hepatitis in dogs is identified early on, the treatment can begin quickly. When the treatment is in effect and in a timely manner, there's a great chance of healing acute hepatitis in a dog’s system before it has a chance of turning into chronic hepatitis. If treated early enough, the chances of hepatitis becoming fatal or detrimental to their health are drastically reduced.
After successful treatment of hepatitis in a dog, the animal can be kept completely symptom-free using a life-long treatment of zinc gluconate or penicillamine.
Dietary Adjustments for Dogs with Hepatitis
Generally, feeding a low protein diet will be recommended for most dogs with hepatitis, but the amount of protein should only be decreased after a consultation with a vet. This highly depends on an individual dog, causes of hepatitis, and a case by case basis (68, 69).
The starting point is a diet with protein restricted to 2.1‐2.5 g protein/kg body weight.
Fat does not need to be restricted for dogs with hepatitis, and supplementation with Vitamin K is also unnecessary in a large majority of cases. More commonly, Vitamin B supplements may be recommended due to risks of urinary loss of water‐soluble B vitamins in the dog.
Before, salt restriction was recommended for both humans and dogs with hepatitis. However, this stance has changed recently, because severe restriction of sodium has negative effects on nutritional state, diet palatability and it has limited efficacy (70, 71).