ALT Activity
Alanine aminotransferase (ALT) is an enzyme mainly found in liver cells (hepatocytes) and plays a key role in amino acid metabolism by converting alanine into pyruvate. ALT is normally present at low levels in the blood, but when liver cells are damaged, the enzyme is released, resulting in increased ALT activity. It is commonly measured in blood biochemistry and is a useful marker for detecting liver cell injury in dogs.
ALT facilitates protein and energy metabolism, especially in the liver, where nutrients are processed and distributed. Small amounts are also present in other tissues such as muscle, but increased ALT activity in dogs is primarily linked to liver cell damage.
Health Effects
Elevated ALT indicates liver cell injury but does not reveal the underlying cause. Levels may rise due to liver inflammation, toxins, infections, metabolic disorders, or reduced blood flow. Mild increases can be transient, while larger elevations may be associated with lethargy, reduced appetite, vomiting, weight loss, or jaundice.
ALT reflects liver cell damage but not overall liver function, so additional tests may be needed.
Monitoring ALT activity supports early detection of liver disease and guides diagnosis and treatment. Follow-up testing may be required depending on severity, and regular health checks are important for at-risk dogs.
Mode of Inheritance
ALT activity is not inherited as a single trait, though genetic factors may influence susceptibility to liver conditions. Most changes are caused by acquired rather than inherited factors.
Important to Know
Genetic testing for ALT activity should be seen as a risk indicator, not a diagnosis. Some variants, such as those near the GPT gene, can lower baseline ALT activity, meaning dogs may have naturally lower ALT even with liver disease. Most tests analyse only one known variant, and additional factors likely exist. A normal result does not rule out elevated ALT.
ALT is a dynamic clinical parameter affected by disease, medication, diet, and environment. Because genetic tests do not reflect real-time enzyme activity, direct clinical measurement remains the most reliable method for evaluating liver health. Genetic testing can help assess risk, but clinical evaluation and laboratory results will always be necessary, therefore, at the moment, we do not offer genetic tests for ALT activity.