Serum markers of bone metabolism in dogs.

OBJECTIVE: To establish reference values for a panel of serum markers of bone turnover in dogs of various ages. ANIMALS: Dogs in 4 age groups (0 to 1 year; 1 to 2 years; 3 to 7 years; > 8 years). PROCEDURE: Serum concentrations of the carboxyterminal propeptide of type-I procollagen (PICP) and the aminoterminal propeptide of type-I procollagen (PINP), both markers of type-I collagen synthesis (hence, bone formation), were measured by use of commercial human radioimmunoassay kits. Serum concentrations of the carboxyterminal cross-linked telopeptide of type-I collagen (ICTP), a marker for type-I collagen breakdown (hence, bone resorption), also were measured by use of a commercial human radioimmunoassay kit. Serum osteocalcin (OC) concentrations and alkaline phosphatase (ALP) isoenzyme activities were measured by use of techniques developed specifically for dogs. RESULTS: As expected, the highest values for all of the markers were found in young dogs (< 12 months old). Concentrations of OC and ICTP decreased with age, and were lowest in dogs > 8 years old. Total ALP and bone-specific ALP activities initially decreased with age, then increased in dogs > 8 years old. CONCLUSIONS AND CLINICAL RELEVANCE: Serum markers of bone turnover may be useful diagnostic and prognostic tools for management of dogs with musculoskeletal disorders.