Symptoms of elevated dog liver enzymes are dependent upon which enzymes are at abnormal levels and the degree to which those enzymes are elevated. The liver performs many metabolic functions including the removal of waste products, detoxification of the blood, secretion of bile for fat metabolism and production of blood-clotting factors. Many of these functions rely on the liver specific enzymes, and associated symptoms can occur if the enzymes are secreted at abnormal levels.
Liver Specific Enzymes
ALT (Alanine aminotransferase), or SGPT (serum glutamic puruvic transaminase), is secreted when liver cells die due to infection or an interruption of blood supply. A temporary increase of approximately two to three times the normal level is not considered significant and increases can be due to anticonvulsants or glucosteroids, or non-hepatic ailments. Elevation occurs in viral or toxic hepatitis or obstructive jaundice.
AST (Aspartate aminotransferase), or SGOT (serum glutamic oxaloacetic transaminase), is found in muscle tissue and red blood cells. An increase of AST is more likely indicative of severe liver disease than ALT. Increased levels can also indicate damage to liver or heart cells or a muscular disease.
GGT (Gamma-glutamyl transpeptidase) levels that are abnormal signify liver disease due to an obstruction of the bile ducts, called cholestasis, or may be indicative of pancreatitis.
SAP (Serum alkaline phosphatase) levels may increase in cases of certain cancers, but are not significant indicators of cancer in canines.
Symptoms of Elevated Liver Enzymes
A damaged liver that is not performing properly will secrete increased levels of these enzymes and can result in a display of associated conditions. Symptoms of elevated liver enzymes in dogs may include
- Poluria (increased urination)
- Polydipsia (increased water consumption)
- Diarrhea or constipation
- Vomiting
- Lethargy
- Depression
- Bleeding disorders
- Ascites (accumulation of fluid in the abdominal cavity)
- Loss of appetite or anorexia
- Pale gums (may indicate anemia)
- Pale gray stools
- Weight loss
- Anemia
- Bloody stool (may indicate internal bleeding)
- Jaundice (yellowing of skin, mucous membranes and the normally white area of eyes)
Diagnosis of liver disease can be difficult because the early symptoms may be nonspecific and similar to numerous hepatic or non-hepatic ailments. The liver can also maintain seemingly normal function until approximately 75 percent of its cells are destroyed. Symptoms may not appear until advanced stages of a disease. Laboratory blood and urine tests can confirm elevated liver enzymes and x-rays, ultrasound or a CT scan may be necessary to determine the related ailment.
Causes of Elevated Liver Enzymes
Causes of elevated liver enzymes may be hepatic or non-hepatic disease. Liver disease, infectious hepatitis, hepatic shunts or liver cancer can be associated with elevated enzyme levels. Pancreatitis, Cushing's disease, diabetes, leptospirosis and heartworm infection are among the non-hepatic ailments that can affect the liver and the secretion of enzymes.
Metabolic diseases, such as obesity or hypothyroidism, are conditions that involve low metabolic rates that may cause elevated liver enzymes. Some prescription drugs such as corticosteroids or anticonvulsants can cause temporary elevation of liver enzymes that return to normal levels after the medication is no longer administered.
Treatment of elevated dog liver enzymes is dependent upon the degree of the enzyme's elevation and the stage of the associated illness. An early and definitive diagnosis can improve the response to treatment.