Enlarged Liver in Dogs: Causes, Symptoms, and Treatment

Your dog’s liver is an impressive organ, helping them to filter toxins, digest food, and clot blood when necessary. Not only does the liver contribute to many functions that are essential for life, but changes to its size and structure (such as enlargement) can also hint to your veterinarian that your dog may have other health concerns. Read on to find out what causes an enlarged liver in dogs, as well as how to treat it.

What Is an Enlarged Liver in Dogs? 

An enlarged liver in dogs is often a sign of an underlying condition. In veterinary medicine, an enlarged liver is referred to as hepatomegaly.

The liver rests just behind the diaphragm, which is the thin muscle that separates the chest from the abdomen. The bottom of the liver usually has sharp margins and doesn’t extend far past the ribs.

Most commonly, your veterinarian can monitor the size of your pet’s liver through abdominal palpation and X-rays of the abdomen. If the veterinarian sees that the margins of the liver appear rounded and that the bottom of the liver is extending into the abdomen past the edge of the ribs, they may determine the liver is enlarged.

Causes of Enlarged Liver in Dogs

Some causes of enlarged liver in dogs are harmless. Others may indicate a manageable underlying disorder. In some cases, hepatomegaly in dogs indicates a life-threatening condition.

Causes of liver enlargement in dogs include:

• Cushing’s disease (hyperadrenocorticism)
• Chronic hepatitis
• Nodular hyperplasia (a benign, age-related change)
• Breed-related or inherited conditions, such as inherited amyloidosis in the Chinese Shar-Pei or copper accumulation in the livers of some Bedlington Terriers
• Drugs or toxins, such as phenobarbital or blue-green algae, which cause liver damage in dogs
• Infectious diseases, such as leptospirosis, infectious canine hepatitis (canine adenovirus type 1), or histoplasmosis (fungal disease), which can cause liver failure in dogs
• Diabetes mellitus
• Right-sided heart failure
• Liver cancer

Symptoms Associated with Enlarged Liver in Dogs

Most symptoms are actually related to the condition that is causing hepatomegaly rather than the enlarged liver itself. Symptoms may include:

• Abdominal distention or pot-bellied appearance
• Excessive urination and thirst (polyuria and polydipsia)
• Excessive panting
• Appetite and weight changes
• Vomiting or diarrhea
• Changes to coat, such as loss of hair on sides
• Jaundice
• Lethargy
• Neurologic signs like pressing the head into the wall and acting mentally unaware (hepatic encephalopathy) 

Diagnosing Hepatomegaly in Dogs

Dogs with enlarged livers typically come to the veterinarian for other symptoms or for their routine wellness check.

Determining if the liver is enlarged is usually pretty simple. Some veterinarians may be able to tell if your pet has an enlarged liver by looking at them and palpating their abdomen, but if there’s doubt, an X-ray or ultrasound of the abdomen typically shows hepatomegaly. Mild cases may be more difficult to detect.

Determining the reason for liver enlargement in dogs is a bit more complicated. When your veterinarian is trying to figure out what’s causing the liver to enlarge, they’ll almost certainly perform routine bloodwork, an analysis of the pet’s urine, and imaging (X-rays and/or abdominal ultrasound).

Other tests may include:

• Confirmatory blood testing for Cushing’s disease
• Chest X-rays and echocardiogram (if heart disease is suspected)
• Testing bile acids to determine how well the liver is functioning
• Ammonia testing to determine how well the liver is functioning
• Assessment of abdominal fluid if present
• Coagulation testing to see how well the blood clots
• Hepatic cytology, in which liver cells are examined under a microscope
• Liver biopsy, in which a small section of liver is removed for examination under a microscope
• Computed tomography (CT) of the abdomen (this may be recommended if cancer is known or suspected)

How to Treat an Enlarged Liver in Dogs

Treatment of liver enlargement is geared toward the underlying cause. In some cases, such as an infection, the liver may return to its normal size after treatment. In other cases, such as chronic hepatitis or liver cancer, the liver may not fully return to its normal size.

During routine wellness visits, the veterinarian palpates the abdomen and checks liver function with routine bloodwork. In younger dogs, these appointments should occur at least annually. In older dogs, usually at least every six months. If your dog has an active condition that’s impacting their liver, monitoring may initially be more frequent. Once your pet is stable, your veterinarian can help you decide how regularly to do check-ups.

Treatment for Specific Causes of Liver Enlargement

Liver Injury

In dogs who are experiencing liver injury that requires hospitalization, supportive care will be initiated. This can include:

• Intravenous fluids
• Anti-inflammatories
• Nutritional management
• Medications to prevent vomiting and treat nausea
• Blood transfusions or anticoagulants
• Pain medication

Infections

Antimicrobials are usually administered for infectious causes of liver enlargement, in addition to supportive care.

For bacterial infections, common antibiotics include:

• Penicillins
• Cephalexin
• Enrofloxacin
• Metronidazole 

Doxycycline is commonly used for leptospirosis, and for fungal infections, antifungals like itraconazole are recommended. Viral infections are managed with supportive care.

Inflammatory and Endocrine Disorders

For inflammatory disorders like chronic hepatitis, which often has an autoimmune component, treatment may include steroids and medications that suppress the immune system.

For endocrine disorders like Cushing’s disease or diabetes, medications are given to manage the hormonal disorder. For Cushing’s disease, this is typically trilostane, while diabetes is managed with insulin and dietary changes.

Liver protectants may also be recommended, including SAM-e (S-adenosylmethionine), silybin, and ursodiol. These typically come in the form of supplements.

Cancer

When cancer is suspected, treatment options depend on the extent of the tumor and whether it has spread. Treatment may include surgery to remove tumors, chemotherapy, and radiation therapy.

Liver Cirrhosis 

When liver disease in dogs is chronic or uncontrollable, it will eventually lead to liver cirrhosis, which can make the liver small and nodular and have devastating effects on liver function. This is not reversible and is the end stage for liver disease. 

How to Prevent Enlarged Liver in Dogs

Most causes of liver enlargement can not be prevented. Discussion of your pet’s risk can help you determine the appropriate steps to reduce the risk of infectious diseases, such as vaccination against leptospirosis.

Although most causes aren’t necessarily preventable, paying close attention to your pet’s behavior and regular veterinary exams can help catch disorders that cause liver enlargement early.