Pergolide mesylate administration does not decrease blood thyroid hormone concentrations and thyroid function in horses.

This research studied the effect of Pergolide medication on thyroid hormone levels and thyroid functions in horses, and found that Pergolide doesn’t appear to decrease thyroid hormone levels or affect the functioning of the thyroid.

Research Methods

The researchers used an analytic, observational, cohort study design with a sample of six horses aged between 17 and 24 years, and weighing 530 to 599 kilograms. Over a period of six days, each of these horses was given a daily oral dose of 1 milligram of Pergolide mesylate, a drug usually used to treat a pituitary gland disorder in horses. Researchers then measured the total T4 (tT4) hormone daily for 11 days, before, during, and after the treatment.

Additionally, they carried out Thyrotropin-releasing hormone (TRH) stimulation tests on the horses on the first and last day of the Pergolide treatment. These tests involved measuring the concentration of additional thyroid hormones, namely total T3 (tT3), tT4, and free T4 (fT4), at baseline, and again two hours and four hours after administering the TRH.

Results

• No change in tT4 hormone levels was observed related to the use of Pergolide during and after treatment
• TRH administration led to significant increases in tT3, tT4, and fT4 hormone concentrations
• No significant effect of Pergolide on any thyroid hormone concentration was detected

Conclusions

Based on the findings of the study, the researchers concluded that Pergolide does not seem to impact either the hormone levels or the function of the thyroid in horses. They also inferred that proteins binding with agents like Pergolide do not necessarily affect thyroid hormone levels. In the context of horses with pituitary pars intermedia dysfunction, lower thyroid hormone levels are likely a result of the dysfunction itself, rather than a side effect of the Pergolide treatment.