Cirrhosis of the Liver in Dogs - Causes, Symptoms and Treatment

Fibrosis is a type of wound healing which results in normal functioning tissue being replaced with non-functioning connective tissue. Essentially, it replaces functioning tissue with scar tissue. When this occurs in the liver, it is known as hepatic cirrhosis or cirrhosis of the liver. Cirrhosis is sometimes referred to as end-stage liver disease as the fibrosis can progress so much the liver will no longer be able to function.

Liver cirrhosis in dogs is an irreversible disease and is produced by the combination of two factors:

• Chronic damage the liver: generally caused by liver diseases or poisoning that affects the liver.
• Failure in the regeneration mechanism: the liver is an organ with a great power of regeneration, so much so that it is capable of completely regenerating from only 30% of its size. However, when this regeneration mechanism fails, cirrhosis appears.

The attempts of the liver to regenerate its hepatocytes give rise to an abnormal proliferation of these cells. The cells form nodules without structure or function, which are known as regeneration nodules. Since the tissue is no longer functioning, the liver will not be able to perform its organism-saving function. The more advanced the cirrhosis, the less the liver will function.

As the damaged liver parenchyma is replaced by connective tissue, severe fibrosis further compromises liver structure and function. Sometimes abnormal proliferation of the biliary system is stimulated at the same time, leading to biliary hyperplasia.

At the microscopic level, the following characteristics can be observed:

• Regeneration nodules: with loss of the lobular structure typical of the liver.
• Severe fibrosis: with greater presence of connective tissue.
• Biliary hyperplasia: usually occurring when there is damage to the bile ducts.

At the macroscopic level, the characteristics that will be observed in cases of liver cirrhosis are:

• Decreased liver size: the liver will become noticeably smaller.
• Firm consistency: due to the deposit of connective tissue.
• Nodular surface: due to the formation of regeneration nodules.

For more general information, take a look at our article on liver failure in dogs.

The causes that can cause cirrhosis of the liver in dogs include:

• Anticonvulsant treatments: fundamentally associated with the administration of phenobarbital, a powerful hepatotoxic agent.
• Chronic hepatitis: in the dog, chronic hepatitis can be caused by infectious agents (such as canine adenovirus type 1, Ehrlichia canis or Leishmania infantum), toxic agents such as copper, aflatoxins and drugs.
• Plant alkaloid intoxications: much more frequent in herbivorous animals than in carnivores.
• Biliary obstruction or chronic cholestasis: when bile cannot flow from the liver to the duodenum.
• Secondary passive hepatic congestion: leading to congestive heart failure. Find out more information with our article on the signs of heart failure in dogs.

In the initial phases of the process, dogs may remain asymptomatic or show nonspecific clinical signs such as vomiting, diarrhea, polyuria, polydipsia, anorexia, weight loss, apathy and/or depression. However, once the functional reserve capacity of the liver is exceeded, clinical signs suggestive of liver disease will appear.

Generally, the structural and functional alteration of the cirrhotic liver leads to liver failure characterized by the following clinical picture:

• Ascites: abdominal dilation due to the presence of free fluid in the abdomen When the liver is unable to maintain albumin levels in the blood, there is a decrease in oncotic pressure that causes ascites. Here you can find more information about ascites in dogs, specifically its causes and treatment.
  
  
• Jaundice: yellowish discoloration of the mucous membranes caused by an excess of bilirubin (yellow pigment) that is deposited on the tissues. In dogs, it is usually initially detected at the level of the sclera (the white of the dog's eyes). It is also a symptom which appears in other canine liver problems, including hepatitis in dogs.
  
  
• Hepatic encephalopathy: it is a neurological condition that is produced by the accumulation in the blood of neurotoxic substances not metabolized by the liver, mainly ammonia. Signs that may be seen in these dogs include altered level of consciousness (lethargy, stupor, and eventually coma), weakness or ataxia, pressure of the head against the wall or floor, circling, and seizures. Our related article provides more information on hepatic encephalopathy in dogs.
  
  
• Acquired portosystemic shunts: consists of the formation of vessels that abnormally connect the portal vein with the vena cava. It occurs as a consequence of portal hypertension secondary to cirrhosis.
  
  
• Bleeding tendency: it occurs as a consequence of the decrease in the synthesis of coagulation factors, platelet function and the absorption of vitamin K.
  
  
• Photosensitization: occurs when photosensitive substances are not inactivated in the liver and are deposited in the skin, giving rise to inflammatory and necrotic processes in the epidermis.
  
  
• Hepatocutaneous syndrome: characterized by the appearance of lesions at the much-cutaneous junctions and pads of dogs. It is produced by an alteration in epidermal maturation secondary to essential amino acid deficiency that occurs during liver failure.

The diagnosis of cirrhosis of the liver in dogs will usually involve the following diagnostic tests:

• Clinical history and general examination: special attention should be paid to the presence of clinical signs associated with liver failure, described in the previous section.
• Blood tests with liver profile: checking levels of total proteins, albumin, liver enzymes (ALT, GGT and alkaline phosphatase), ammonia, glucose and bile acids. Check here to find out what are the normal glucose levels in dogs.
• Abdominal ultrasound: an image suggestive or compatible with cirrhosis can be observed, characterized by the presence of hyperechoic nodules (whitish in color on the ultrasound image) that correspond to the regeneration nodules typical of this process. However, this image is also compatible with the presence of a liver tumor, so ultrasound does not provide a definitive diagnosis.
• Abdominal x-ray: the purpose of the x-ray is to provide information about the size of the liver, since ultrasound usually gives a somewhat subjective idea. In cirrhosis the liver will be decreased in size.
• Biopsy and histopathological analysis: a sample can be taken percutaneously (with biopsy needles) or surgically (by laparotomy or laparoscopy). In the histopathological analysis, it will allow the definitive diagnosis of cirrhosis by detecting a deposit of connective tissue (fibrosis) that delimits the regeneration nodules.

Although cirrhosis is an irreversible process, it is important to establish adequate treatment in order to prevent the progression of fibrosis and control the signs and complications associated with this process. Specifically, the treatment of cirrhosis in dogs is based on the following factors:

• Slow the progression of fibrosis: antifibrotics such as colchicine may be given, although there are no studies conclusively showing their effectiveness.
• Dietary Management: proper nutritional management is critical to maintaining body condition in dogs with liver disease. An easily-digestible diet, rich in easily-assimilated carbohydrates and low in fat, should be provided. It will only be necessary to restrict protein levels in dogs when they have hepatic encephalopathy. In cases of copper poisoning, the level of copper in the diet should also be restricted.
• Treatment of complications: in animals with ascites, diuretics such as furosemide or spironolactone should be administered. In cases of severe ascites, an abdominocentesis should be performed to evacuate the abdominal fluid. In dogs with hepatic encephalopathy, the production and absorption of toxins in the gut should be prevented by the use of laxatives (such as lactulose) and oral antibiotics.
• Support treatment: in a complementary way, hepatoprotectors and antioxidants such as ursodeoxycholic acid, vitamin E or silymarin can be administered.

To know more about how to prevent other organ function problems, take a look at our guide to renal failure in dogs.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

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