Evaluation of plasma carboxy-terminal cross-linking telopeptide of type I collagen concentration in horses.

The research evaluates a human assay for measuring carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I) in horses, investigating relationships with age, osteocalcin concentration, and whether there are any circadian rhythms in these concentrations. The study establishes the assay as a useful tool to monitor bone metabolism changes in horses.

Research Methods and Subjects

• The study worked with 75 clinically normal horses to determine the efficiency of an automated electrochemiluminescent sandwich antibody assay (ECLIA) designed for humans, in assessing CTX-I in horses.
• Methods used included a specificity test (dilution test) and recovery calculation to evaluate cross-reactivity between equine serum CTX-I and CTX-I antibodies in the human ECLIA.
• The concentration of serum osteocalcin, another indicator of bone metabolism, was measured using an equine-specific osteocalcin radioimmunoassay.
• The team also conducted a 24-hour sampling period, taking hourly blood samples to investigate potential diurnal variations in plasma CTX-I and serum osteocalcin concentrations.

Research Findings

• The dilution test showed a high correlation (r > 0.99) between expected serum CTX-I levels and measured serum CTX-I levels, validating the use of the human ECLIA for horses.
• The calculated CTX-I recovery in the test ranged between 97.6% to 109.9%, indicating good accuracy.
• A correlation was found between plasma CTX-I and serum osteocalcin concentrations, indicating that both are reflective of bone metabolism status.
• An inverse correlation was found between plasma CTX-I concentration and the age of the horse, however, the paper does not provide information on how this relationship was quantified or the implications it may have on equine health.
• Interestingly, the study found no significant circadian variations in plasma CTX-I and serum osteocalcin concentrations.

Conclusions

• The findings suggest that the fully automated CTX-I ECLIA, originally created for humans, can successfully be utilized for the evaluation of plasma and serum samples from horses.
• The ability of the assay to monitor equine bone metabolism changes could make it a valuable tool for managing equine health, particularly in older horses or those with bone-related health issues.
• However, the lack of diurnal fluctuations in serum osteocalcin and plasma CTX-I concentrations means that testing can be carried out at any time of day without concern for time-based concentration changes influencing the results.