ALT was selected as the comparator biomarker in this study as it is considered the gold standard marker for hepatocellular damage, being highly sensitive and reasonably specific for hepatocellular injury across species.34 Its main limitations are that increased ALT activity can occur with non-hepatic injury, creating false positives, and increased ALT activity does not always correlate with hepatic histopathological findings,26,34,35 highlighting the need for new biomarkers for hepatic disease in companion animals. The gene discussed is GPT; the disease is liver disorder.