Chronic Hepatitis in Dogs

What is Chronic Hepatitis?

Chronic hepatitis (CH) is a progressive liver condition caused by chronic inflammation. Over time, the ongoing inflammation can lead to liver cell death (apoptosis). These dead cells are replaced by scar tissue (fibrosis), which can lead to reduced liver function.

Important liver functions that can be affected include filtering toxins out of the blood, breaking down fats, and storing energy. The liver may also lose the ability to produce important proteins and other substances important for health. Ultimately, if the liver becomes too damaged, cirrhosis and liver failure can occur.

What causes CH?

In most cases, the underlying cause is idiopathic, meaning it cannot be determined or is unknown. Many potential causes have been linked to idiopathic CH, including:

• Bacterial infection such as leptospirosis or leishmaniasis
• Protozoal infection such as neosporosis or toxoplasmosis
• Toxins, including aflatoxin and certain medications
• Immune-mediated (abnormal, damaging response of the immune system)

Many cases can be linked to a buildup of copper in the liver caused by either a defect in normal copper metabolism or from increased copper ingestion. Some breeds have a recognized genetic problem with copper regulation, including Bedlington terriers, Dobermans, Dalmatians, West Highland white terriers and Labrador retrievers, but potentially all breeds and mixed breeds may be affected.

What dogs are more commonly affected?

Most dogs diagnosed with CH are middle-aged, between 4 and 10 years old. It may be diagnosed in older dogs.

What are the signs?

Clinical signs of CH mirror the extent of liver damage/scarring. In early stages, there may be minimal or no signs and the disease may only be noticed on routine wellness screening tests. Signs of early disease include vomiting, diarrhea, decreased appetite, vomiting, increased drinking, and urination.

As the disease progresses, dogs may develop more specific signs of liver disease, including:

• Jaundice: yellowing of the skin and mucous membranes
• Hepatic encephalopathy: a condition that affects the brain, resulting in varying signs including extreme lethargy and/or dullness, an unsteady gait, drooling, sudden blindness, seizures, and head pressing
• Ascites: fluid buildup around the abdominal organs often creating a bloated appearance and potentially abdominal pain

How is CH diagnosed?

Your veterinarian may see clues that your dog has CH when they perform a thorough examination, history, urine testing and baseline blood testing (complete blood count [CBC] and biochemistry profile). 

Liver enzymes such as alanine transferase (ALT) and alkaline phosphatase (ALP) may be elevated; however, they can be elevated with many conditions and, in some cases of CH, these enzymes may be normal. Your veterinarian may suspect CH when they look at trends in bloodwork over time, such as persistent elevations in ALT and ALP, especially if bilirubin becomes elevated. Your veterinarian may recommend bile acid testing to better assess liver function. Many dogs with CH have abnormal bile acid results, but not all.

"Your veterinarian may suspect CH when they look at trends in bloodwork over time."

In more severe or advanced cases of CH that compromise liver function, albumin, a blood protein, will decline. Other substances produced by the liver, including bilirubin, glucose, urea, will also decline. Your veterinarian may also recommend testing to determine how well your dog’s blood clots (coagulation testing), as reduced liver function will cause prolonged bleeding.

An ultrasound may be recommended to look for signs consistent with chronic hepatitis or other diseases affecting the liver. However, an exact diagnosis of CH requires a liver biopsy, which involves removing tiny pieces of your dog’s liver to examine them under a microscope.

How is CH treated?

Depending on your dog’s condition, hospitalization and supportive care may be required, including intravenous fluids. Supportive care may include treatments for hepatic encephalopathy or bleeding disorders secondary to liver dysfunction.

Chronic hepatitis treatment usually involves a multifaceted approach, including addressing the underlying cause (if found), ensuring adequate nutrition, reducing inflammation that leads to fibrosis (scarring), and providing general liver support. Your veterinarian will discuss the best therapies for your dog.

Addressing the underlying cause may include:

• Discontinuing a medication or exposure to an identified toxin
• Treatment with antibiotics if an infection is determined or suspected
• Using penicillamine or trientine to chelate copper (bind copper and remove it in the urine) in dogs with confirmed copper storage disease

Nutrition:

• Diet should be balanced and sufficiently appealing to ensure your dog eats enough calories.
• A reduction in dietary protein may be recommended if your dog shows signs of hepatic encephalopathy.
• A diet low in copper may be recommended for dogs with copper storage disease.

Anti-inflammatory:

• Your veterinarian may recommend medications to reduce inflammation, including corticosteroids such as prednisone, cyclosporine, and azathioprine, or treatment with immunosuppressive medications such as prednisone, cyclosporine, azathioprine, or mycophenolate.

Liver support:

• Nutraceuticals that have protective or antioxidant effects may be recommended, including vitamin E, S-adenosylmethionine (SAMe – Denosyl®, Novifit®, Zentonil®), and silybinin – the active compound in milk thistle (Marin®, ZentonilAdvanced®, Denamarin®).

Other treatments:

• Ursodeoxycholic acid (Ursodiol®) improves bile flow through the liver, reduces inflammation, and may modify harmful immune responses.
• Angiotensin receptor blockers (losartan, telmisartan) may reduce or prevent scarring.

What is the prognosis for dogs with CH?

Unfortunately, the prognosis depends on how aggressive the underlying disease is and how much liver scarring occurred before diagnosis. Some patients may live for several years, especially if diagnosed earlier in the course of the disease. Routine monitoring may be recommended to ensure the best treatment. If liver function is already reduced, then the prognosis may be poorer.