Every Embark test screens ALT activity (via a GPT genetic variant) —one of several values your veterinarian measures on routine blood work to gauge your dog’s liver health. To best leverage your dog’s GPT result in his or her health care, it’s important to understand how your vet can use this clinical tool to establish a baseline ALT value for your dog, in order to monitor any future deviation. Let’s dig in.
What is ALT?
Alanine Aminotransferase (ALT) is a cytoplasmic enzyme found mainly in hepatocytes (liver cells). Although it can occasionally be found elsewhere, such as skeletal muscle and kidney and red blood cells, ALT is the most liver-specific of the liver enzymes, so it’s commonly used by veterinarians as a measure of liver health.
When the liver is inflamed or damaged, ALT activity can increase dramatically. This makes ALT a sensitive marker of liver injury. Conditions, such as Cushing’s disease, inflammation, infection, or cancer of the liver, and certain medications and toxins, can sometimes cause an elevation of ALT measured in the blood.
What Embark tests for
An Embark test screens for a variant (mutation) in the GPT gene which has a codominant mode of inheritance. The variant does not cause liver disease. But dogs with at least one copy of the ‘A’ allele are likely to have lower ALT activity (‘low normal’) than dogs with zero copies of the ‘A’ allele (‘normal’). So slight elevations in ALT, which could indicate liver injury, can go undiagnosed with standard blood testing.
Only a genetic GPT test can help vets understand a dog’s genetic predisposition and indicate the need to establish an accurate ALT baseline early enough to monitor deviations. That’s why Embark has offered this test since launch—and has recently given the results even more prominence on your dog’s profile. Learn more about ALT activity here—and check out figure 2 to compare ALT levels in dogs with zero, one, or two copies of the variant.
How veterinarians use this tool to enhance treatment
Embark’s GPT results can alert vets to ALT levels that may not be flagged by the diagnostic laboratory as elevated. The results can be used to:
Establish your dog’s baseline
Knowing Embark’s GPT results, your veterinarian may choose to measure a baseline ALT value when your dog is healthy. Here’s how vets generally characterize most changes in ALT measurement:
- Mild: 2- to 3-fold elevation in activity
- Moderate: 5- to 10-fold elevation in activity
- Marked: >10-fold elevation
Adjust monitoring protocols: If a dog’s normal ALT value is low and your vet knows about the presence of the GPT variant, he or she may adjust monitoring protocols or flagged test values. This can be key when monitoring subtle changes in liver health or as vets monitor ALT levels in dogs being administered medications like NSAIDs.
Provide personalized medicine: This clinical tool is the beginning of personalized medicine for dogs.
The bottom line for your breeding program
Dogs with one or two copies of the variant can lead completely normal lives, and do NOT need to be removed from a breeding program. In fact, at this time, there aren’t even any specific recommendations to only breed at-risk dogs to clear dogs.
But it is extremely important to share GPT results with your veterinarian: You can email your dog’s Veterinary Report directly through your Embark profile. Knowing if your dog has one or two copies of the variant can improve how blood tests are interpreted now and may lead to earlier diagnosis of liver issues down the road.
Want to learn more?
Read this article co-authored by our CSO, Adam Boyko, Ph.D.