Researchers Study Abnormal Behavior Prevalence in Racehorses

Equine stereotypic behaviors are more important than some might think.

Many horse owners don't think about equine stereotypic behaviors until they own a cribber, a stall walker, a weaver, or a horse that passes his time with any abnormal behavior. But these stereotypies are more important than some might think: They could indicate compromised equine welfare. Recently, Chilean researchers set out to evaluate the prevalence and factors associated with stereotypies and other undesired behaviors in a population of racehorses.

Tamara Tadich, DrVetSci, of the Universidad Austral de Chile, in Valdivia, and colleagues recently camped out at two Chilean racetracks to evaluate the prevalence of stereotypies and other abnormal behaviors in stalled Thoroughbred racehorses. Tadich said that while the Chilean horse racing industry is growing, "there are no policies in relation to the housing and management of these horses, which is important taking into account that … racehorses in Chile spend their entire competitive lives housed at the racetrack yards."

Compiling data on the prevalence of abnormal behavior in these racehorses will likely provide important information regarding how their housing and management practices impact their welfare, she said.

Tadich and colleagues closely observed 743 Thoroughbred racehorses of varying ages and sexes at two racetracks in Santiago, Chile (417 horses at Racetrack A and 326 at Racetrack B). They recorded detailed information about the horses—including age, sex, bedding type, feeding protocol, training routine, and how much social contact they had with other horses (none, visual, or visual and tactile)—in addition to recording any stereotypic or abnormal behavior and any methods used to prevent or impede those behaviors.

The team classified weaving, stall walking, nodding, pawing, and stall kicking as undesirable behaviors with a locomotor origin; they considered cribbing or wind sucking, wood chewing, coprophagia (ingesting feces), bedding consumption, and eating or licking other objects as oral abnormal behaviors. They classified cribbing, wind sucking, weaving, and stall walking as stereotypies

Upon reviewing their results, the team found that:

  • Eighty-two horses (11.03%) performed some stereotypy or abnormal behavior. Of those, five (6%) performed more than one abnormal behavior and one performed three abnormal behaviors. For the two racetracks, the total prevalence rate of stereotypies was 6.32% and the prevalence of abnormal behaviors was 5.52%, which the researchers noted was a low prevalence compared to previous research in other countries.
  • Although both racetracks had similar husbandry practices, the team noted that horses stabled at Racetrack B showed significantly more abnormal behaviors than horses stabled at Racetrack A. - At Racetrack A, the most commonly observed stereotypy was weaving (2.4% prevalence), while at Racetrack B the most commonly observed was cribbing (3.4% prevalence). The researchers only observed bedding consumption, pawing, and eating or licking objects at Racetrack B.
  • More mares exhibited stereotypic or abnormal behaviors than did stallions or geldings. "There is no obvious explanation why the mares in the current study should be more likely to perform stereotypies," Tadich said. "It might be related to hormonal factors, temperament, or an unidentified external factor."
  • For the entire study population, 85% of the horses were bedded with wood shavings, while 15% were bedded with straw. The team found that bedding with wood shavings was a significant risk factor for horses exhibiting stereotypic or abnormal behaviors.
  • For the study population, 86% of horses had only visual contact with other equids, while the remaining 14% had no contact—visual or tactile—with other horses. "No significant association was found between the presence of visual contact and the development of stereotypies," Tadich said, noting that this finding is contrary to previous research. - All horses consumed oats and alfalfa hay, and the majority (54%) received feed twice or three times daily. The remaining horses were fed once daily.
  • All study horses spent an average of 86 minutes per day outside their stalls. "The time spent out of the box was practically the same for all the horses … so the possible influence of time spent stabled on the development of stereotypies could not be evaluated," she noted.
  • Horse managers attempted to control the abnormal behaviors in 43% of the cases through various means depending on the behavior displayed; many of the control methods included physical restriction. "This avoids the real problem and becomes a risk for the welfare of the animal," Tadich said. "If stereotypies are a response to specific challenges that have to be faced inside the (stall), the restriction of the behavior does not represent a solution and may even cause secondary problems owing to increased stress."

"Our finding that 11.03% of the racehorses directly observed in this study presented at least one abnormal behavior is relevant for animal welfare and suggests that some changes to the management and husbandry would be beneficial," Tadich said.

"I would suggest increasing the percentage of forage in the meals of the horses and the frequency of feeding," she concluded. "Although due to the management of racehorses increasing the time spent out of the stall or in contact with other horses is difficult, it could help prevent these behaviors."

The study, "Prevalence and Factors Associated with Abnormal Behaviors in Chilean Racehorses: A Direct Observational Study," was published in the Journal of Equine Veterinary Science.

Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.