Why Are My Dog And Cat’s Blood GGT Levels High Or Low?

Ron Hines DVM PhD

To see what normal blood and urine values are for your pet, go here

For an explanation of causes of most abnormal blood and urine tests go here

To see how tests are often grouped, go here

  What To Do When My Dog Or Cat’s Liver Tests Are High?  

Your Pet’s Gamma Glutamyl Transferase Levels aka = GGT, GGTP, GT, GGT

Gamma-glutamyltransferase or GGT is an enzyme with far too many names. No one is absolutely sure what its function is, (GGT is probably involved in metabolizing the amino acid, glutamine, or glutathione peptides). But veterinarians know that much of it is found in the cells that make up your pet’s liver (hepatocytes).

The level of many of the enzymes that liver cells (hepatocytes) contain rise when your pet’s liver is injured and these cells begin to leak. But many of them (such as AP and AST) are found elsewhere too. So other non-liver health problems can also cause their levels to go up. High GGT levels however are close to 90% accurate in identifying the location of the problem as being in your pet’s liver – issues such as hepatobiliary disease (liver and bile tract disease) and  cholestasis (obstructions to the flow of bile).

Reasons Why Your Dog Or Cat’s GGT Levels Might Be Elevated:

Various types of liver damage will raise GGT levels in your pet’s blood. This test seems particularly sensitive for detecting liver damage in cats (in cats, GGT often rises sooner than AP). However GGT is not commonly elevated in cats with hepatic lipidosis. GGT levels tend to rise significantly any time bile flow anywhere from its formation in the pet’s liver to its deposition in the small intestine is blocked (=cholestasis). Obstructions to that flow of bile can have many causes. It could be gall stones. It could be bile duct inflammation. It could be liver tumors. It could be secondary to pancreatic inflammation – particularly in cats with Triad disease (cholangiohepatitis).

Corticosteroid medications can also raise your pet’s GGT levels, as can drugs given to control epilepsy (eg phenobarbital).

The degree of elevation in GGT levels in your pet does not necessarily indicate how severe its liver problem is or will become.

Reasons Why Your Dog Or Cat’s GGT Blood Enzyme Levels Might Be Decreased:

In humans, low GGT has been associated with hypothyroidism (not a common problem in cats) or low blood magnesium levels. We do not know if that is true in dogs and cats as well, but veterinarians tend to assume it is.

Complementary Tests:

AP, ALT, GLDH,bile acids, bilirubin (if bilirubin is normal:  bile acids)

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