Tongue ties might allow racehorses to breathe better in certain situations, but study results suggest they can also cause signs of stress—including those that have been tied regularly in the past. | Photo: Anne M. Eberhardt/The Horse

A tied tongue might allow racehorses to breathe better in certain situations. But that doesn’t mean the horse perceives the tie as a positive experience. Recent study results suggest tongue tying causes significant signs of stress in racehorses—including those that have been tied regularly in the past.

“The behavioral and physiological changes we detected were suggestive of a stress response, and this merits further research to determine whether the costs to the horse are offset by the benefits,” said Samantha Franklin, BVSc, PhD, Dipl. ACVSMR, RCVS recognized specialist in Equine Medicine (Sports Medicine), of the Equine Health and Performance Centre in the University of Adelaide School of Animal and Veterinary Sciences, in Australia.

Franklin presented the work of her honors student, Laura Latimer-Marsh, BSc, during the 2017 International Society for Equitation Science Symposium, held Nov. 22-26 in Wagga Wagga, Australia.

In their study, Franklin, Latimer-Marsh, and their fellow researchers investigated the reactions of 12 Standardbreds, averaging 11 years of age. They studied the horses before, during, and after having their tongues tied with a commercially available elastic tie for 20 minutes. In a second (control) test, they studied the horses before, during, and after 30 seconds of tongue manipulation without a tie.

They found that the horses showed significantly more head-tossing, ear-flattening, and gaping of the mouth when the tongue tie was applied compared to when receiving tongue manipulation only, Franklin said. In fact, the horses with previous tongue-tying experience showed more head-tossing and mouth-gaping than the naive horses.

“That was different from our hypothesis and from suggestions from other researchers,” she said, indicating that the horses don’t “get used” to the tongue tie.

Furthermore, the horses showed much more lip-licking than controls once the tie was removed, Franklin added. “When the tongue tie was in place horses weren’t able to lick their lips,” she noted.

Salivary concentrations of cortisol (the ”stress hormone”) increased after tongue-tying, Franklin said. However, the researchers did not notice any notable differences in cardiac readings or eye temperature (other potential indicators of stress) among treatments.

More than 30% of Australian racehorses race with tongue ties, said Franklin. In a separate study, 23% of trainers reported problems associated with tongue ties, including lacerations, bruising, swelling, dysphagia (difficulty swallowing), and aversive behavior. But very little research has been carried out on the topic.

“Further research is needed that will enable racing and sport horse regulatory bodies to make informed decisions about the appropriate use of tongue ties in horses,” she said.