Liver Disease in Dogs

A dog with liver disease may experience illness associated with various functions of this vital organ. The liver is crucial to digestion, helping a dog metabolize fat, protein, carbohydrates, vitamins, and minerals. Additionally, it filters out toxins and waste found in foods and medications. Disorders of the liver, collectively called liver disease, can lead to a really sick pet. However, some liver problems are more serious than others, and the liver has the remarkable ability to regenerate in the early stages of disease. Learning how to spot liver issues before they become a full-blown disease can prevent liver damage and get a sick dog back to health.

What Is Liver Disease?

Liver disease refers to any abnormality in the liver that prevents it from functioning normally. There are several different types of liver diseases. Bile duct obstruction occurs when the tubes that carry bile from the liver to the gallbladder become blocked. A portosystemic shunt (also called a liver shunt) happens when blood from the stomach, intestines, pancreas, and spleen bypasses the liver, preventing the blood from being properly detoxified. Autoimmune disease can cause scarring of the liver. Liver tumors, most common in older dogs, can be cancerous or they can be benign but still affect your pet by pressing on the surrounding liver or other organs.

Symptoms of Liver Disease in Dogs

Many types of liver problems can appear in a dog, causing a multitude of symptoms. Often there are no symptoms until the disease has progressed, which is why regular exams and blood work are important, especially in older animals.

Jaundice—a yellowing of the eyes, tongue, skin, or mucous membranes—is a tell-tale sign that something is abnormal with your dog's liver. Other signs are more subtle or may be attributed to other illnesses. Any sign of severe gastrointestinal upset or neurological problems like loss of balance or seizures should be evaluated by a veterinarian. Of course, signs of sickness other than overt jaundice may be caused by a problem unrelated to the liver. Again, a visit to the vet will help identify the problem.

Causes of Liver Disease

Liver disease has many different causes, depending on the type. Each type is unique to a particular form of the illness.

• Acute liver disease can develop after exposure to a toxic substance or poison, or from exposure to excessive heat (never leave your pet in a hot car!).
• Some toxins can cause different organs to fail, leading to secondary liver damage.
• Bile duct obstruction presents from generalized inflammation, an infection, a tumor, gallstones, or a build-up of thickened bile in the gallbladder called a mucocele.
• A portosystemic shunt may be present at birth or develop due to another liver problem.
• Chronic hepatitis can be caused by an overactive immune system, infection, toxins, or other damage that the liver could not completely recover from.
• Viral, bacterial, fungal, or parasitic infections can all cause chronic liver problems, too. This bacteria, when contracted by an unvaccinated dog, can cause severe liver damage.

Diagnosing Liver Disease in Dogs

If liver disease is suspected, a vet will order lab work to evaluate organ function. Elevated liver enzymes found in the blood, like alanine transaminase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP), can indicate a problem. Additionally, the blood levels of bilirubin, a substance found in bile, and albumin, a protein made by the liver, provide information about overall liver health.

Blood sugar levels, cholesterol, and levels of urea nitrogen—a byproduct of protein metabolism—can also give information on whether the level of liver disease constitutes liver failure. A complete blood count may indicate the presence of an infection or inflammation.

Abdominal imaging, like radiographs (X-rays) or an ultrasound, may reveal scar tissue and tumors in or around the liver region. A liver biopsy may be recommended to check for the presence of bacteria, cancer cells, and more and is often the only way to get a definitive diagnosis for the cause of the liver disease.

Treatment

The treatment options for acute liver disease depend on the type of disease and the degree of damage done to the liver. Fluids and electrolytes, and restricted activity are the recommended protocol for pets who have been acting sick. Medications and liver supplements are often used as well.

Bile duct obstruction can sometimes be remedied with medications like ursodiol. However, for full duct obstruction, surgery is often necessary. Surgery has a high success rate for liver shunts and can be a cure for most dogs, however not all shunts can be repaired surgically and these cases will need lifelong management with diet and medication. Antibiotics and antiviral medications can be given in the presence of infection.

Chronic active hepatitis—not reversible or curable—is often managed with medications and a restricted diet. Treatment for liver tumors or cancer will depend on test results and may involve surgery, chemotherapy, and the administration of medications.

Medications and supplements, like Denamarin, can help many dogs with liver disease or damage live for years with minimal symptoms. In some cases, dietary changes are also necessary. The response to treatment depends on the individual dog, but compliance from the owner is a major component to success. Be sure to adhere to your vet's recommendations for medications, diet, and follow-up testing and exams.

Prognosis for Dogs With Liver Disease

The outlook for a dog with liver disease depends on the cause, type, and severity of the disease. Dogs with congenital abnormalities like portosystemic shunts or benign tumors can often be cured with surgical intervention. Chronic inflammatory liver disease is usually incurable but can often be managed for years with medications and dietary changes. Liver cancer carries the worst prognosis of the liver disease types; quality of life is managed by surgery, chemotherapy, medications, and diet for a limited life expectancy from the time of diagnosis.

How to Prevent Liver Disease

While keeping your dog healthy involves routine wellness exams, there are other ways to assure liver health. Refrain from feeding your dog fatty foods as this may cause pancreatitis, which can secondarily affect the liver. Make sure your pet is fully vaccinated to prevent infectious causes of liver disease such as leptospirosis. Do your best to keep toxic substances out of your dog's reach, and provide plenty of opportunities for your dog to exercise since a fit, active dog is less likely to suffer from liver disease brought on by a sedentary lifestyle of overeating.

Types of Liver Disease in Dogs

Bile Duct Obstruction

Bile duct obstruction can happen as a result of myriad conditions involving any of the digestive organs because all are linked to or affected by the liver. The obstruction may be due to inflammation of surrounding tissues, parasites, fibrosis, benign tumors, or cancer.

Diagnosis of obstruction requires laboratory tests, x-rays, a bile acid test, and ultrasound. If the cause is pancreatitis, then dietary measures and certain medication may relieve the obstruction. In some cases, though, surgery is necessary. The dog’s gallbladder may even need to be removed. This procedure, followed by dietary modifications, will help relieve discomfort and allow the inflamed liver to heal.

Portosystemic Shunt (Liver Shunt)

A portosystemic shunt is an abnormal vascular connection between the liver and other organs. It allows toxins, proteins, and nutrients in the intestines to bypass the liver and pass directly into systemic blood circulation. Most shunts are congenital, meaning some dogs are born with them.

Symptoms, which include ataxia and seizures, are most likely to occur after eating. Diagnosis requires tests such as blood work, a urinalysis, liver function tests, x-rays, an ultrasound, and a CT scan. The treatment for a portosystemic shunt is surgery to narrow or close the vascular connection.

Chronic Hepatitis

Chronic hepatitis is inflammation and cell damage in the liver that lasts longer than a few weeks. This happens because of an abnormal influx of white blood cells responding to a previous infection or ingested toxins. It can also happen as a result of an autoimmune disease or bacteria like leptospirosis (found in the urine of rodents). Chronic hepatitis can affect any breed of dog at any age but is more likely to appear in older dogs.

The signs of chronic hepatitis can be gastrointestinal or neurological, and it may cause jaundice. A veterinary exam and bloodwork may suggest liver impairment, but biopsy is the only way to accurately diagnose the condition. There is no cure for chronic hepatitis, but dietary management, targeted medications, and supportive therapy can help some dogs live comfortably for months or years with this disease.

Tumors

Primary liver tumors are those that begin in the liver. They may be benign or malignant and are most common in dogs over 9 years of age. More commonly, liver tumors are a result of metastasis from other organs. Symptoms include weight loss, jaundice, vomiting, fever, and distended abdomen. Surgery and chemotherapy may help relieve a dog’s discomfort and extend its lifespan by a few months to a few years, depending on the stage of the disease.