Effects of single-dose intravenous phenylbutazone on experimentally induced, reversible lameness in the horse.

The research examines the effects of a single dose of phenylbutazone, a nonsteroidal anti-inflammatory drug, on horses suffering from adjustable heart bar shoe-induced lameness. It was found that phenylbutazone was efficient in alleviating lameness and controlling heart rate, without significant effects on packed cell volume and cortisol levels.

Research Context and Objective

• This study aimed to explore the impact of phenylbutazone (PBZ), an anti-inflammatory drug, on lameness in horses caused by an adjustable heart bar shoe. This lameness is a reversible condition often used as a model for equine foot pain.
• The hypothesis being tested was that PBZ could provide relief for this kind of lameness.

Methodology

• An experiment was conducted involving eight Quarter Horse mares. These mares underwent four different treatment scenarios on a random basis, involving a combination of either PBZ or a saline placebo, and either with or without the presence of lameness.
• Heart rates and lameness scores were recorded at varying intervals over a nine-hour period, during which the treatment (PBZ or placebo) was administered at the first hour.
• Moreover, samples were taken from the jugular veins at designated hours and were analyzed for various indicators such as packed cell volume (PCV), cortisol, and drug concentrations.
• Data analyses were employed to identify any observable effects of PBZ on the chosen indicators.

Results

• PBZ was found to have lowered lameness scores from the second to the eighth hour post administration, and also reduced heart rates from the second through the sixth hour.
• It was found not to have significantly altered PCV and had a minimal impact on cortisol levels.
• The mean plasma concentrations of PBZ seven hours after administration was recorded between 7.2 and 7.5 micrograms per milliliter.

Conclusion

• The study concluded that PBZ was truly effective in relieving equine lameness induced by an adjustable heart bar shoe model.
• However, it was found that cortisol and PCV levels were not sensitive enough to distinguish between horses that received PBZ and those that were given the saline placebo.