What Does AST Mean in Dogs and Cats?
Quick answer
AST is an enzyme found in liver cells and muscle. It rises when either tissue is injured, so on its own it cannot say which is affected. Vets read AST next to ALT and muscle markers. A raised AST can follow liver stress, muscle strain, or even a difficult blood draw.
What is AST?
Aspartate aminotransferase is present in liver, heart, and skeletal muscle cells and is released when those cells are damaged.
Reference range
[Range pending sourced table] Reference ranges vary by lab and species. Use the range printed on your pet's report.
What can raise AST
- Liver cell injury
- Muscle injury or intense exercise
- Difficult blood draw
- Sample handling issues
What can lower AST
- Low values are rarely significant
Dogs vs cats
In dogs
In dogs, AST often rises alongside ALT in liver conditions or after muscle strain.
In cats
In cats, AST can be a sensitive marker of liver cell injury.
Why one value rarely tells the whole story
Because AST comes from both muscle and liver, it only becomes meaningful next to ALT and a muscle marker. Hydration, recent meals, stress during the visit, medications, and how the sample was handled can all shift a result. Vets look at the whole panel, your pet's symptoms, and the trend across tests over time.
Conventional interpretation
Vets compare AST with ALT and creatine kinase to tell liver from muscle sources.
Whole-pet context
Recent hard exercise, falls, or rough play can matter, as can appetite and energy.
Supportive options are not a cure. Check with your veterinarian before adding any supplement.
Questions to ask your vet
- Is the rise from liver or muscle?
- Should we check a muscle enzyme?
- Was the sample difficult to collect?
- How does this compare with my pet's previous results?
Frequently asked questions
Can exercise raise AST?
- Yes. Strenuous activity or muscle injury can raise AST temporarily.
Is AST more important than ALT?
- Neither alone is enough. They are read together.
What is a normal AST range?
- Reference ranges vary by laboratory, analyzer, and species. Use the range printed on your pet's report and ask your vet how your pet's result compares.
Should AST be rechecked?
- Your veterinarian decides based on how far from range the value is, your pet's symptoms, and other results. Trends over time are often more useful than one result.
Related lab values
Related guides
Educational support only. Not a diagnosis or substitute for veterinary care.
Have your pet's report?
Upload a PDF or photo and see AST and every other value plotted against its range.
Upload a lab report