This medication is also described as a veterinary treatment. In the past, hypothyroidism was considered to be common in “easy keepers” with cresty necks and top-line fat. We now know that these horses are not really hypothyroid but are insulin resistant. That said, we still use thyroid medication to treat horses that are overweight, insulin resistant and at risk for laminitis.
Thyroid medication provides levels of active thyroid hormone. This has a variety of effects, especially increasing metabolic rate and causing weight loss. It is used frequently today to treat EMS (Equine Metabolic Syndrome) and is often used as an adjunct treatment in horses with Cushing’s Disease (PPID).
Equine thyroid powder is a fine, grayish powder manufactured by several companies and in various sized tubs. The common dosage form is 12mg levothyroxine unit powder. This is usually added to feed and is readily accepted by most horses. Once a horse is on thyroid medication, it is best not to discontinue it without your vet’s knowledge. When we do discontinue this medication and other hormone supplements, we typically taper the dose down over a period of days.