Indiana Horse Racing Commission Implements Strict Thyroid Supplementation Restrictions – Horse Racing News

During its meeting on March 1, 2022, the Indiana Horse Racing Commission passed a new rule regulating thyroxine administration. Effective immediately for both flat and harness racing, thyroid supplementation is now prohibited.

According to the advisory disseminated by the IHRC, the administration of thyroxine has been found to be given in racehorses unrelated to the horses’ thyroid health. The practice of prescribing thyroxine to large numbers of racehorses has drawn public scrutiny and has resulted in inquiries about the legitimacy of its use, as the occurrence of primary hypothyroidism in horses is rare, especially in young, fit racehorses.

It is now prohibited to have possession of thyroxine, any thyroid analog, or thyroid supplement without meeting the conditions set forth in the new rule. Both of the following conditions must be met in order to administer thyroid supplements:

  1. A thyrotropin-releasing hormone (TRH) response test has been performed by a commission-licensed veterinarian and supports a diagnosis of hypothyroidism in the horse. (A T3 or T4 test without stimulation of the thyroid is insufficient to diagnose hypothyroidism.)
  2. A commission-licensed veterinarian has submitted the TRH response test result to the equine medical director, and the equine medical director approves the thyroxine prescription based on their independent determination that the test result confirms the hypothyroidism diagnosis.

If approved by the equine medical director, the horse shall be treated with only Federal Drug Administration approved medications for hypothyroidism prescribed by a veterinarian. Possession of any thyroid supplements that are not pursuant to a veterinary prescription is prohibited.

The prescription for thyroxine or any other thyroid hormone or thyroid hormone analog administration shall not exceed ninety (90) calendar days, after which the prescription must be reauthorized by the equine medical director under either of the following circumstances:

  1. The equine medical director has determined that the horse has benefited from the previous thyroxine, thyroid hormone, or thyroid hormone analog treatment after reviewing the horse’s medical records and consulting with the attending veterinarian.
  2. The hypothyroid diagnosis has been reconfirmed under the requirements described above.

A horse administered thyroxine or any other thyroid hormone or thyroid hormone analog, pursuant to these new rules, is ineligible to start in a race for thirty (30) calendar days after the last administration.

If a horse is currently being administered a thyroid supplement, administration of the supplement shall be discontinued, and a TRH test conducted after a thirty (30) day washout period before the horse is eligible to breed.

The full advisory is available here.

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