Which statement best describes ALP in foals?

• A. It is a liver enzyme that is normally elevated in growing foals
• B. It is always a sign of liver disease when elevated
• C. It is not present in foals
• D. It declines with age

Answer: (A)

Alkaline phosphatase comes from multiple tissues, primarily liver and bone. In foals, rapid bone growth drives a lot of bone-derived ALP into the blood, so total ALP is often elevated even when the liver is not diseased. That means a high ALP in a foal is commonly a normal finding tied to growth, rather than a sign of liver failure. The key idea is that ALP elevation in young horses reflects active bone formation, and it tends to decline as growth slows with age. If there’s concern about liver disease, clinicians look at other liver-specific indicators and, if needed, isoenzyme testing to separate bone from hepatic sources.