The liver is the largest internal organ and one of the most versatile, performing over 500 vital functions. It filters blood, removes toxins, produces bile for digestion, stores vitamins and glycogen, manufactures essential proteins (including those needed for blood clotting), and metabolizes medications. Because the liver is involved in so many processes, liver disease can manifest in a wide variety of ways and affect virtually every body system.

Common causes of liver disease in dogs include:

• Chronic hepatitis: Ongoing inflammation of the liver that gradually leads to scarring (fibrosis) and eventually cirrhosis. It can be immune-mediated, caused by copper accumulation, or have no identifiable cause (idiopathic). Certain breeds, including Doberman Pinschers, Labrador Retrievers, Cocker Spaniels, and Bedlington Terriers, are predisposed to specific forms of chronic hepatitis.
• Portosystemic shunt (PSS): An abnormal blood vessel that bypasses the liver, allowing toxins to circulate in the bloodstream without being filtered. This can be congenital (present from birth) or acquired. Small breeds like Yorkshire Terriers, Maltese, and Havanese are more commonly affected by congenital shunts.
• Toxin exposure: The liver is the primary organ for detoxification, making it vulnerable to damage from ingested toxins including certain plants (sago palm, mushrooms), medications (acetaminophen, xylitol), chemicals, and heavy metals.
• Infectious diseases: Leptospirosis, infectious canine hepatitis, and certain fungal infections can cause acute liver damage.
• Liver tumors: Both primary liver tumors and metastatic cancer (cancer that has spread from other organs) can compromise liver function.
• Copper storage disease: Certain breeds accumulate excess copper in the liver, leading to progressive damage. Bedlington Terriers, Labrador Retrievers, and Dalmatians are among the most affected breeds.

One of the liver's remarkable characteristics is its ability to regenerate and function even when significantly damaged. Dogs can maintain normal liver function with as little as 20-30% of their liver working properly. While this resilience is a strength, it also means that clinical signs of liver disease often do not appear until the damage is quite advanced.

Because the liver is involved in so many bodily functions, liver disease can produce a wide array of symptoms. Some are obvious, while others are subtle and easily overlooked. Being aware of these signs, particularly in breeds predisposed to liver problems, can help you catch the disease early when treatment is most effective.

Common signs of liver disease include:

• Loss of appetite and weight loss: Often one of the earliest signs, your dog may eat less, become picky, or refuse food entirely.
• Vomiting and diarrhea: The liver plays a central role in digestion, and gastrointestinal upset is common in liver disease.
• Jaundice (icterus): A yellowing of the skin, gums, whites of the eyes, and inner ear flaps. Jaundice occurs when bilirubin, a waste product normally processed by the liver, builds up in the blood. It is one of the most telling signs of liver disease.
• Increased thirst and urination: Liver disease can affect the body's fluid regulation, leading to increased water consumption and urine output.
• Lethargy and weakness: Your dog may be less active, sleep more, and lose interest in activities.
• Distended abdomen (ascites): Fluid accumulation in the abdominal cavity due to portal hypertension or decreased protein production. The belly may appear swollen and feel fluid-filled.
• Behavioral changes: Hepatic encephalopathy, caused by toxins (especially ammonia) that the liver can no longer filter, can cause confusion, disorientation, aimless wandering, head pressing, circling, and in severe cases, seizures.
• Easy bruising or prolonged bleeding: The liver produces clotting factors, and when it is compromised, blood may not clot normally.

If your dog shows jaundice, a distended abdomen, or neurological signs such as disorientation, seek veterinary care urgently. These signs indicate significant liver compromise that requires prompt attention. For more subtle signs like decreased appetite and lethargy, schedule a veterinary appointment for bloodwork, which can often detect liver enzyme elevations before clinical signs become severe.

Diagnosing liver disease involves a combination of blood tests, imaging, and sometimes biopsy. Your veterinarian will use these tools to determine not only that the liver is affected but also what specific type of liver disease is present, which is essential for guiding treatment.

Diagnostic tools include:

• Blood chemistry panel: Liver enzymes (ALT, AST, ALP, GGT) and bilirubin levels indicate liver cell damage and function. Bile acids tests specifically assess liver function and are useful for detecting portosystemic shunts.
• Complete blood count: May reveal anemia or changes in red blood cell shape that suggest liver disease.
• Clotting tests: Assess the liver's ability to produce clotting factors.
• Abdominal ultrasound: Visualizes the liver's size, shape, and internal structure, and can detect tumors, shunts, and fluid accumulation.
• Liver biopsy: Often necessary for a definitive diagnosis, particularly in chronic hepatitis. Biopsies can be obtained through ultrasound-guided needle aspiration, laparoscopy, or surgical exploration.

Treatment depends entirely on the underlying cause:

• Chronic hepatitis: May involve immunosuppressive medications (if immune-mediated), copper chelation therapy (if copper-related), anti-inflammatory drugs, antioxidants (SAMe, silymarin/milk thistle), and hepatoprotective supplements.
• Portosystemic shunt: Congenital shunts may be corrected surgically, with excellent outcomes in many cases. Medical management with a low-protein diet and lactulose (to reduce ammonia absorption) is used before surgery or when surgery is not an option.
• Toxin exposure: Decontamination (if caught early), IV fluids, liver protectants, and supportive care.
• Liver tumors: Surgical removal may be curative for some primary liver tumors, particularly hepatocellular carcinomas that are confined to a single liver lobe.
• Infections: Appropriate antimicrobial therapy and supportive care.

Supportive care for all forms of liver disease often includes a liver-supportive diet, SAMe and silymarin supplements, ursodiol (to improve bile flow), and management of complications such as ascites and hepatic encephalopathy.

The prognosis for liver disease in dogs varies enormously depending on the type, cause, severity, and how early it is detected. The liver's remarkable ability to regenerate means that even dogs with significant liver damage can sometimes recover substantially if the underlying cause is addressed.

Prognostic factors:

• Dogs with congenital portosystemic shunts that are corrected surgically often have an excellent prognosis, with many living normal lifespans.
• Chronic hepatitis caught early, before cirrhosis develops, can often be managed for months to years with medication and dietary changes.
• Dogs with cirrhosis (end-stage scarring) have a more guarded prognosis, though many can still be managed comfortably with supportive care for a period of time.
• Acute liver failure from toxins can be fatal if severe, but dogs that survive the initial crisis often recover fully due to liver regeneration.
• Prognosis for liver tumors depends on the type. Single hepatocellular carcinomas removed surgically can have survival times exceeding 3-4 years.

Ongoing care for dogs with chronic liver disease includes:

• A liver-supportive diet that is moderate in high-quality protein, restricted in copper (if relevant), and supplemented with easily digestible carbohydrates
• Regular bloodwork monitoring, typically every 2-4 months, to track liver enzymes and function
• Daily supplements as recommended by your veterinarian (SAMe, milk thistle, vitamin E)
• Prompt attention to any new symptoms or changes in behavior
• Avoidance of medications and substances that stress the liver

Living with a dog with liver disease requires attention and dedication, but many dogs with managed liver conditions enjoy years of good quality life. Your veterinarian is your most important partner in this journey, helping you navigate treatment decisions and monitoring your dog's progress. With early detection and proper care, many families are pleasantly surprised by how well their dog can do.