Biochemical and haematological effects of phenylbutazone in horses.

The research article assesses the physiological, biochemical, and haematological effects of administering phenylbutazone, an anti-inflammatory medication, to horses over a period of 15 days. The study results indicated measurable changes in some horses’ health markers attributed to the drug.

Methodology and Experiment Grouping

• The study employed five pairs of horses. Two distinct groups were formed for the experiment. Group A was given phenylbutazone in daily doses as recommended by the manufacturer for 15 consecutive days while the horses in Group B were administered a placebo in equivalent doses.

Identification of Changes in Measured Parameters

• Across both groups, significant changes were recorded in some physiological, biochemical, and haematological variables. This highlighted that there may be some background instability in these parameters in horses.
• Group A, which received phenylbutazone, showed notable decreases in serum total protein, albumin, plasma pH, viscosity, and magnesium levels. They also showed an increase in the albumin: globulin ratio. These changes did not occur in the placebo group (Group B), suggesting that the alterations could be due to phenylbutazone or its metabolites.

Implications and Suggestions from the Findings

• The pH changes, although significant, are believed to be unimportant from a toxicological perspective. However, the decrease in protein concentration is a concern. It may be caused by a protein-losing enteropathy or decreased synthesis in the liver – both considered detrimental effects.
• One horse that received phenylbutazone presented clinical signs of toxicity, manifested as lethargy, inappetence, and oedema. This specific horse also showed evidence of hepatotoxicity and haematological changes, indicating potential adverse effects of phenylbutazone.
• The study concluded that the drug’s dose recommendations should not be exceeded. In fact, the duration for which the highest dose is given should be shortened.
• The team suggest that serum or plasma protein concentration could aid in identifying suspected cases of phenylbutazone toxicity in actual clinical scenarios. This could help in deciding whether the dosage of the drug should be reduced or the therapy stopped altogether.