The liver is also susceptible to injury because of its role in metabolising, detoxifying, and storing various toxic compounds. As a result, the dog may be suffering severe hepatic injury by the time a diagnosis is made. Diagnosis of liver disease can be challenging because dogs often show non-specific physical signs or do not show any specific clinical signs altogether.
Liver has a remarkable capacity to regenerate following hepatic injury, and an explicit hepatic dysfunction does not develop until more than 70% of liver’s capacity is lost. This makes recognising subtle signs even more critical for early diagnosis. Annual and bi-annual exams should therefore be made to evaluate the state of functioning of Liver.
Evaluation of Liver disease in dogs:
Mild anemia, increase in monocytes and neutrophils is commonly seen with inflammatory liver diseases.
Liver enzymes, including ALT, ALP, AST and GGT should be measured in case of suspected liver disease. Hepatocellular enzymes ALT & AST are markers of liver cell damage as they are released from damaged hepatocytes. On the other hand, biliary enzyme ALP will increase when bile flow is impaired. GGT is thought to indicate possible liver damage. The higher the abnormal level, the more likely there is liver or bile duct damage.
Bilirubin is a byproduct of the routine destruction of red blood cells occurring in the liver. It is normally released as bile in the faeces. Elevated levels of bilirubin (jaundice) might indicate liver damage or certain types of anemia. Other conditions with increased destruction of RBCs can also cause elevated bilirubin despite normal liver functioning.
Albumin is one of several proteins made in the liver. Your dog’s body needs this protein to fight infections. Low serum albumin and total protein can be indicative of liver failure or diseases such as cirrhosis and chronic hepatitis
Urea & Ammonia
Damage limits the ability of the liver to process ammonia. A low urea can occur in canine liver disease due to reduced ability to synthesise urea from ammonia. Failure of the liver to detoxify ammonia results in hyperammonaemia.
Radiography and Ultrasonography
Abdominal radiography is done to assess the size and shape of Liver. Dogs with acute liver disease can have normal to enlarged livers. In presence of abdominal fluid, radiography can be inaccurate. Ultrasonography is highly effective in the diagnosis of liver disease. Hepatic lesions, gallbladder and biliary disease, and vascular aberrations may be detected and characterised by ultrasonography.
The most common liver disorders in dogs
Acute Liver failure
Hepatic injury can incapacitate liver’s ability to meet metabolic and detoxification needs. The loss of function can happen in days or weeks. Acute liver failure is less common than chronic liver failure, which develops slowly. You will see onset of nonspecific physical signs in your dog such as lethargy, GI disturbances, vomiting, blood in stools and even encephalopathy. Hepatotoxins are one of the most common causes of hepatic injury. Hepatotoxins are endogenous or exogenous substances (drugs, toxins, xenobiotics) that cause hepatic injury. Liver is highly susceptible to damage. Drugs such as anabolic steroids, azole antifungals, NSAIDs, phenobarbital etc may cause hepatic toxicity. Heavy metals, aflatoxins/mycotoxins, xylitol, endotoxins (salmonella, E coli, clostridium perfringens), herbal remedies (green tea extract, licorice, Chinese herbal meds etc) can also cause hepatic injury.
Dogs most often become infected with canine hepatitis by consuming faeces, saliva, nasal discharge or urine from infected dogs. Granulomatous Hepatitis can result due to unique inflammatory response that may be idiopathic, immune mediated or a response to a bacterial, fungal, viral, or parasitic infection; a manifestation of drug-induced liver injury; or a manifestation of some underlying malignancy. Holistic herbal remedies and treats or food from countries with unregulated manufacturing processes are also one of the risk factors. Blood work will show high liver enzymes, bilirubinuria, low BUN, and/or monocytosis with chronic inflammation. Chronic Hepatitis can result from inflammation in liver by infectious agents like bacteria, virus etc. It leads to invasion of white blood cells and cell death. Toxic damage can be caused by poisons ingested by the dog or by abnormal accumulation of substances like copper. Exposure to food borne toxins like aflatoxins, cyanobacteria, overuse of NSAIDs, endotoxemia affiliated with IBD, copper associated hepatopathy are all known causes.
Hepatic encephalopathy (HE) is a decline in brain function that occurs as a result of severe liver disease. This leads to buildup of toxins in liver, which can lead to brain damage. HE is commonly associated with acute liver failure, portosystemic shunts, hepatic fibrosis/cirrhosis. Common signs in dogs – lethargy, disorientation (compulsive pacing, head pressing etc), changes in mood, seizures etc.
This is used to describe abnormally enlarged liver. There are a number of diseases that can affect the functioning of a dog’s liver and lead to enlargement. Common causes – infectious or chronic hepatitis; heart disease, drugs – corticosteroids, phenobarbital etc; bile duct obstruction; xenobiotics or herbal toxicity; hemolytic anemia, tumors, cystic lesions etc. Most common signs of hepatomegaly are abdominal distention and discomfort. Blood work will show thrombocytopenia, high liver enzyme activity, and/or variable bilirubin & albumin values. Abdominal ultrasonography will help determine liver size and surface contour.
Early common physical signs of Liver disease to look out for
- Nausea, Vomiting or other GI issues
- Diarrhea or yellow, orange-colored stools
- Yellowing of the gums, tongue or the whites of the eyes
- Changes in coat, dull & brittle hair
- Increased water consumption and urination
- Blood in stools or urine
- Loss of muscle mass
- Loss of weight and appetite
- Changes in behavior, such as irritability, lethargy, or depression
- Swelling of the abdomen due to enlargement of the liver or fluid build up
- Poor coordination