Bleeding from the nostrils—technically termed epistaxis—has long been recognized as a problem affecting racehorses during or after intense exercise. The underlying cause of the condition, however, remains elusive.

Looking at the official race records of horses that experienced an episode of epistaxis, an Australian research team recently sought to identify risk factors for recurrence as well as determine an epistaxis episode's impact on a horse’s racing career.

Although it's a point of great debate, veterinarians and trainers in the United States have the option of racing horses on the anti-bleeding medication furosemide (commonly known as Salix or Lasix). However, vets and trainers in some other countries don't have that option.

“In Australia, there are no race-day medications allowed in horses,” said Peter Knight, PhD, a researcher in the biomedical science department at Sydney Medical School, who teamed up with members of the University of Sydney Veterinary Science Department for the study. “If a horse bleeds once—defined as blood visible in both nostrils—they get a three-month ban from racing, and a two-month ban from training. If they bleed twice then they get a lifetime ban and must be retired