Physiological, biochemical and haematological effects on horses of a phenylbutazone paste.

The study investigates the effects of a newly scheduled dosage of a medical paste for horses, phenylbutazone, on various biological aspects of the animals, such as their biochemistry, physiology, and hematology. The research found significant changes in some variables in horses treated with the drug, but these changes do not indicate toxicity from phenylbutazone.

Methodology

• The researchers used five pairs of horses in the study. The study was designed as a controlled feeding experiment to evaluate the effects of a new dosage schedule of phenylbutazone.
• One group of horses received the phenylbutazone paste with a loading dose on the first day and a daily dose for the next seven days. The dosage schedule skipped day 9 and 11. The dosage was 8.8mg/kg on the first day, followed by daily doses of 3.3mg/kg from days two to eight, ten, and twelve.
• The other group received the same doses of a placebo paste instead.

Results

• The study observed several significant changes in the drug-treated horses. It found alterations in the horses’ bodyweight, skin temperature, and respiratory rate. Other changes observed were in the glutamate dehydrogenase activity, packed cell volume, mean corpuscular volume, and neutrophil count.
• These variations were seen in the drug-treated group, not in the group treated with the placebo.
• However, the direction and magnitude of the changes did not indicate any toxic effects resulting from phenylbutazone, which was the primary concern for embarking upon the study.

Conclusion

• The researchers concluded that the effects phenylbutazone had on the horses could be considered toxicologically insignificant, as several variables either remained unaffected or changed insignificantly in both groups, even during and after the dosage periods.
• Despite the changes seen in some variables in the drug-treated horses, these alterations were not indicative of toxicity from phenylbutazone, making the new dosage schedule potentially safe for use in horses.