Managing Heaves in Competition HorsesBy Kentucky Equine Research Staff · March 13, 2017
Veterinarians and horses owners can use several medications to help horses cope with heaves, including inhaled corticosteroids such as budesonide. Corticosteroids, however, are tightly controlled in many equine athletic events, and according to a recent study*, severity of heaves (recurrent airway obstruction, RAO) may impact reported budesonide withdrawal times.
Barton and colleagues hypothesized that inflammation in the airway of horses suffering from RAO could alter the way budesonide is absorbed. Specifically, the researchers hypothesized that a combination of exercise and respiratory tract disease would increase the rate of budesonide uptake systemically, thereby prolonging the presence of drug residues in the body, blood, and urine. As a result, the recommended withdrawal times for budesonide might not be applicable to exercising horses with RAO.
To test this theory, horses were administered budesonide and either left at rest or exercised. Blood and urine samples were subsequently collected 4-96 hours after budesonide administration and tested for budesonide-related metabolites.
As suspected, all horses with RAO had significantly higher blood and urine concentrations of budesonide than non-RAO horses, and all RAO horses had budesonide concentrations exceeding the limit of detection at 96 hours. In other words, these horses would test positive at competition. Further, exercise increased systemic levels of budesonide.
Together, these findings confirm the researchers’ suspicion that the interval between budesonide and competition should be increased beyond the currently accepted withdrawal time to avoid a positive test and elimination from competition. Unfortunately, this could mean that horses are competing with uncontrolled heaves, which will negatively impact their athleticism.
“Budesonide and other inhaled medications provide immense relief to horses suffering from respiratory problems; however, management and dietary changes also should be made for maximal relief. This appears especially true for competitive horses that need to be weaned from their medications prior to an event,” advised Kathleen Crandell, Ph.D., a nutritionist for Kentucky Equine Research (KER).
“In addition, studies show the benefits of omega-3 supplementation, such as EO•3, for improving airway function in horses with airway inflammation.”
*Barton, A.K., H. Heinemann, U, Schenk, et al. 2017. Influence of respiratory tract disease and mode of inhalation on detectability of budesonide in equine urine and plasma. American Journal of Veterinary Research. 78:244-250.