Elevated Liver Enzymes in Dogs

What Each Liver Test Means

• ALT (alanine aminotransferase): released when liver cells are damaged. After severe injury it can rise more than 100-fold within 1 to 2 days. Severe muscle injury can also raise it.^3,5
• AST (aspartate aminotransferase): found in liver and muscle, and usually moves with ALT³
• ALP (alkaline phosphatase): rises with reduced bile flow, steroids, Cushing's disease, some anticonvulsants and bone growth. It's the least specific test.^3,4
• GGT (gamma-glutamyl transferase): less sensitive than ALP but more specific for bile duct problems³
• Bilirubin: the pigment that causes jaundice, which can rise from liver disease, bile duct blockage or red blood cell destruction⁹
• Bile acids: measure how well the liver works, and are very high in dogs with shunts but can rise with any liver disease^13,14
• Albumin, glucose and clotting tests: become abnormal only when much of the liver's function is lost^15,8

Causes of High ALT

• Chronic hepatitis, including copper-associated hepatitis^6,12
• Toxins and medicines. Anticonvulsants can raise ALT up to 4 times and corticosteroids about 2 to 3 times.^5,10
• Infections such as leptospirosis^16,8
• Liver tumors and other liver diseases¹⁷
• Severe muscle injury⁵

Causes of High ALP

• Steroids and stress: corticosteroid medicines raise ALP within 5 to 7 days, and chronic stress or illness can raise it 2 to 3 times.^3,4
• Cushing's disease and the vacuolar liver change it causes^4,18
• Some anticonvulsants, usually 2- to 6-fold. This can sometimes reflect liver injury from the drug rather than a harmless effect.^3,4
• Young, growing dogs, which can have values 2 to 10 times adult levels from bone growth⁴
• Breed traits: Scottish Terriers often have high ALP with a vacuolar liver change, and some Siberian Huskies have harmless high ALP^4,18
• Gallbladder and bile duct disease, which can raise ALP dramatically^4,19

How High Is Too High?

Vets grade rises by how many times above the normal upper limit they are. Merck describes under 3 times as mild, 3 to 9 times as moderate and over 10 times as marked, while Cornell calls 2 to 3 times mild and 4 to 5 times moderate, so grading varies.^3,5 But the number alone doesn't show how serious the disease is. A mild but persistent ALT rise can mean significant chronic hepatitis, and in end-stage disease enzymes can fall because few liver cells remain.^6,3

Next Steps After a High Result

1. Review medicines and supplements, including steroids, anticonvulsants and herbal products.^6,5
2. Repeat the test in a few weeks to see if the rise persists.^6,3
3. Check liver function with bile acids, and look for causes outside the liver such as Cushing's disease.^13,18
4. Ultrasound the liver and gallbladder. A normal ultrasound doesn't rule out liver disease.^6,19
5. Biopsy if the cause is unclear, with copper measurement, after clotting tests.^6,7

Can Liver Enzymes Go Back to Normal?

Yes. After a single injury, ALT gradually returns to normal over 2 to 3 weeks, and mild steroid-related ALT rises usually settle within several weeks of stopping the medicine.³ Enzymes from long-term conditions may stay high but can be managed. Many dogs with breed-related or steroid-related enzyme rises live normal lives.^18,4 See liver disease treatment.

Frequently Asked Questions

What is the most common reason for high liver enzymes in dogs?

Often a cause outside the liver, such as steroids, stress, Cushing's disease or medicines.

Can my dog live normally with high liver enzymes?

Many can, depending on the cause. Your vet will check whether the liver is actually diseased.

What can I give my dog for high liver enzymes?

Only what your vet recommends after finding the cause. Some vets suggest antioxidant supplements.

Why does my puppy have high ALP?

Growing bones raise ALP, and young dogs can have levels 2 to 10 times those of adults.

Do high liver enzymes mean cancer?

Usually not. Cancer is one possible cause among many.