Risk Factors for Epistaxis in Jump Racehorses Examined

Both hurdle and steeplechase racehorses had an increased risk of epistaxis when running on firm ground.

Photo: Anne M. Eberhardt/The Horse

Preventing a horse health problem can go from challenging to nearly impossible if veterinarians don’t know why it develops or what makes a horse more or less likely to be affected. Take epistaxis (a fancy name for bleeding from the nose), for instance. Although this condition isn’t uncommon in racehorses, scientists still don’t fully understand why it develops.

“The associations with risk factors are hard to answer,” said Richard Reardon, BVetMed(hons), MVM, PhD, CertES (Orth), Dipl. ECVS, MRCVS, senior lecturer at Edinburgh University’s Royal (Dick) School of Veterinary Studies, in Scotland.

So he and colleagues recently completed a study to try to better understand the risk factors for epistaxis in hurdle and steeplechase horses.

The team found that both hurdle and steeplechase racehorses had an increased risk of epistaxis when running on firm ground. “The link with firm going is not known,” Reardon said, “but thought to be related to impact trauma in the lungs.”

The researchers also determined that both groups of horses were at higher risk when more than 75% of their career starts occurred in flat racing.

Further, the team found racing in the spring and age at first start to be risk factors limited to hurdle racers. “It’s possible the horses that start racing later are genetically predisposed,” Reardon relayed. “Or, an injury during training necessitated a period of rest resulting in a later start and that this, rather than age, was the important risk factor for epistaxis.”

Conversely, running in claiming races and having an increased number of starts in the previous three to six months were steeplechase-specific risk factors. “The reasons for these associations were unclear,” Reardon said. “It appears that horses that ran a lot three to six months before a race are more likely to have epistaxis than those that haven’t run as much. This could be related to generalized fatigue.”

Regardless, once a horse has suffered from the condition, he’s likely to have additional episodes. Because of the strong association with previous episodes of epistaxis, it’s important identify horses that are “bleeders” and manage them carefully, Reardon said.

“Epistaxis is a manifestation of a more severe form of exercise-induced pulmonary hemorrhage (EIPH),” he said. “Identifying horses with this condition by endoscopy and sampling cells from the lungs is a sensible first step.”

Reardon cautioned that EIPH is common in racehorses, so interpreting endoscopy results can be challenging and is best done under an experienced veterinarian’s guidance.

“Identifying at-risk horses and trying to minimize their exposure to the significant factors identified (in previous studies)—not running them on firm ground and not running them in very low temperatures—might be sensible,” he concluded.

The study, “Risk factors for epistaxis in jump racing in Great Britain (2001-2009),” was published in The Veterinary Journal

About the Author

Katie Navarra

Katie Navarra has worked as a freelance writer since 2001. A lifelong horse lover, she owns and enjoys competing a dun Quarter Horse mare.

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