Effects of continuous oral administration of phenylbutazone on biomarkers of cartilage and bone metabolism in horses.

This study evaluates the impact of continuous oral administration of phenylbutazone on certain biomarkers related to cartilage and bone metabolism in horses. The findings suggest that such administration can alter some of these biomarkers in healthy equine joints after briefly administering the drug.

Methodology

• The study involved 11 adult female horses, none of which had clinical or radiographic signs of joint disease.
• These horses were randomly assigned into control and treatment groups.
• The treatment group was given phenylbutazone orally twice daily. For the first three days, the dosage was 4.4 mg/kg, which was later reduced to 2.2 mg/kg for the next seven days.
• During the experiment period, the researchers obtained serum and radiocarpal synovial fluid samples from the horses. These samples were obtained initially and then at regular intervals for the next four weeks.
• To ascertain the impact of phenylbutazone administration, the researchers evaluated biomarkers related to cartilage aggrecan synthesis (chondroitin sulfate 846), type II collagen synthesis (procollagen type II C-propeptide), and type II collagen degradation.
• They also studied the biomarkers relating to bone synthesis (osteocalcin) and resorption (C-terminal telopeptide of type I collagen).

Results

• The analysis of the serum and synovial fluid samples revealed no significant differences between the treatment and control groups in terms of the biomarkers chondroitin sulfate 846, procollagen type II C-propeptide, collagen type II cleavage, and C-terminal telopeptide of type I collagen.
• However, a significant increase was observed in the concentration of osteocalcin in the synovial fluid during treatment in the treated group. This effect was not observed for serum osteocalcin concentration.

Conclusions

• The study concludes that continuous administration of phenylbutazone at recommended doses does have an impact on some biomarkers in healthy equine joints after short periods of administration.
• The increase in osteocalcin concentration could indicate a possible anabolic effect of phenylbutazone administration on periarticular bone or a temporary initiation of osteogenesis in articular chondrocytes or a mesenchymal subpopulation of synoviocytes. However, this needs further investigation for a better understanding.