Dog Liver Enzymes

Dog liver disease is detected by monitoring the enzymes of the liver. When liver enzymes are elevated, it is usually an indication that liver disease is present. However, the liver has the ability to continue functioning normally, even when it is affected and liver enzymes are high. This can make it difficult to diagnosis the presence of liver disease.

However, there are a few liver enzymes which are tested through the blood to help determine the presence of liver disease. These tests cannot be used alone, as each individual test may return a verdict of a normal enzyme count. If the tests are used in conjunction, usually a red flag will be seen somewhere, indicating that your dog has liver disease.

Symptoms of Liver Disease

The symptoms of liver disease can often be confused with symptoms of other ailments, and therefore liver disease may not initially be suspected. However, any of the following signs can indicate a problem with the liver:

  • Vomiting
  • Diarrhea
  • Sudden unexplained loss of weight

Jaundice, or yellowing of the skin and eyes, may also be present in the later stages of liver disease.

Alanine Aminotransferase (ALT)

This is an enzyme that can only be found in the liver. When cells become damaged in the liver, the ALT enzyme will rise. The increase in the ALT enzyme is directly related to the amount of liver cells which are damaged.

It's important to note that an increase of ALT enzyme can also be caused by other conditions in the body, such as heart failure and anemia. This test cannot be relied on solely to determine if your dog has liver disease.

Aspartate Aminotransferase (AST)

This enzyme can be found in other areas of the body besides the liver, such as the heart, kidneys and brain. When there is a rise in AST, there should also be a rise in ALT. They are directly related in diagnosing liver disease. If there is not a rise in both of these enzymes when tested, liver disease may not be to blame for what is suspected in your dog.

Alkaline Phosphatase (ALP)

This enzyme is not liver specific, but it is extremely sensitive during the testing process. An increase in ALP is common in the very beginning stages of liver disease. However, there can also be a natural elevation of ALP in young dogs, so it must be accounted for appropriately.

Additionally, anti-convulsion medications can also cause an increase in the ALP enzyme. This is another issue which must be taken into consideration when testing the ALP enzyme to diagnose liver disease.

Gamma Glutamyltransferase (GGT)

Because this enzyme is also found in the kidney and pancreas, it is not always a fair indication of liver disease. Typically, an increased level of the GGT enzyme in the blood indicates there is a problem with the pancreas or kidneys. The testing of the GGT enzyme can still be used, but it has to be used in the context of testing of the other liver enzymes.