Phenylbutazone and the horse–a review.

This research provides an overview of the clinical uses, side effects of phenylbutazone in humans, horses, and other animals, with an emphasis on horses. The paper concludes that the toxicity of the drug in horses may be lower than in humans and suggests guidelines for its use in veterinary practice.

Clinical uses and side effects

• The paper begins by reviewing the clinical applications and side effects of phenylbutazone, a nonsteroidal anti-inflammatory drug usually used to relieve pain and inflammation in humans and animals. This part provides an overview of the common uses of the drug across species, but primarily focuses on horses.
• The side effects, which include blood dyscrasias (abnormal blood cells), depression, water retention, transient staggering and phlebitis (vein inflammation), are discussed. While some of these negative effects are common in humans, they have not been reported in horses, although some minor side effects such as water retention and depression have been observed.

Toxicity of phenylbutazone in horses

• The paper suggests that despite the lack of documented reports, the toxicity of phenylbutazone in horses is thought to be lower than in humans. This is theorized to be due to several factors such as the lower dosage rates used in horses, faster plasma clearance rates, and the generally younger age of treatment in horses compared to humans.

Guidelines for use of phenylbutazone in veterinary practice

• The paper proposes some guidelines for administering phenylbutazone to horses. It stresses the importance of only using the drug under the control of a vet and only if there are clear clinical indications.
• The research advises against using the drug if there are signs of gastro-intestinal ulceration, clotting defects, or any cardiac, renal or hepatic dysfunction in the horse. The dose rates should be minimized and the medication should be stopped immediately if any side effects are noticed or if there’s no clinical response within four days.
• If a horse requires long-term therapy with phenylbutazone, the paper suggests periodic hematological analyses (blood tests) should be performed to monitor blood cell counts and avoid potential complications.