Feeding Practices and Stereotypies in Horses: A Connection

Have you ever wondered why one horse dozes peacefully in its stall while another finds comfort in crib-biting? Why one horse releases anxiety through weaving while another laps its stall? The answers may lie in their management, according to researchers.

Researchers recently set out to determine the prevalence of stereotypies and to establish if management practices influenced these stereotypies.^* A population of 207 working horses stabled at seven different facilities were enrolled in the study.

Horses represented several breeds and types, including 58 Thoroughbreds, 58 Warmbloods, 24 Arabians, and 67 polo ponies (Thoroughbred, Argentine Polo Pony, Thoroughbred/Quarter Horse, or crosses between these breeds). Both mares and geldings were included in the study, and ages ranged from 7 to 25 years old. All horses were involved in various uses and disciplines, primarily polo, endurance, police patrol, and leisure riding.

All management information for the horses, including feeding practices, was collected through stable records, interviews with caretakers, and on-site visits. Abnormal behaviors were assessed based on an instantaneous scan-sampling method in which an observer recorded the behavior of each horse at 10-minute intervals for 12 hours over the course of three days. Horses were stalled during the observation periods.

Abnormal behaviors were then classified as oral stereotypy (sham chewing, licking, lip-smacking, crib-biting or wind-sucking, tongue-rolling), locomotor stereotypy (weaving, pawing, stall-walking, head-tossing or head-nodding), and redirected behavior (consuming bedding, coprophagy).

Researchers recorded 525 abnormal behaviors during the study. Oral stereotypies had the highest prevalence, followed by redirected behavior, and locomotor stereotypies had the lowest prevalence. More specifically, of the oral stereotypies, sham chewing (repetitive mouth movements that resemble those of mastication but with no feed in the oral cavity) (35% of abnormal behaviors) and licking (15%) were the predominant behaviors. Among the locomotor stereotypies, head tossing or nodding (4%) and weaving (4%) were the most common exhibited by horses. In the final category, redirected behavior, bedding consumption ranked highest (29%).

Of note, the researchers identified interactions between feeding strategies and abnormal behavior. Oral stereotypic behavior was influenced by work intensity and the amount of hay and concentrate fed. Researchers theorized that large amounts of concentrates could increase stereotypic behavior. Amount of hay fed influenced all stereotypies, and the risk of abnormal behavior escalates when less than 15 lb (6.8 kg) of forage is fed daily.

“Diets high in concentrates must often be fed to fuel optimal performance, especially as exercise demands increase,” said Catherine Whitehouse, M.S., a nutrition advisor with Kentucky Equine Research. “As concentrate levels increase, some horses may experience hindgut acidosis, a phenomenon that causes the pH of the cecum and colon to become more acidic.”

Horses often encounter problems as the acidity of the hindgut swells, such as reduced appetite with potential weight loss, low-level colic, and some disposition changes characterized by sourness or unwillingness. Some horses will even engage in stable vices despite no prior history.

A research-proven way to counteract the hindgut acidosis that sometimes accompanies high grain intakes is to feed a buffer such as EquiShure.

“The time-released mechanism in EquiShure guarantees the buffer is released in the hindgut, which is key to its effectiveness,” Whitehouse said, “and anecdotal reports from horse owners indicate EquiShure can alleviate signs of discomfort associated with hindgut acidosis.”

While EquiShure targets the hindgut specifically, Triacton may be appropriate for equine athletes as it is a source of highly digestible calcium that improves bone density and supports digestive health in the stomach and the hindgut.

^*Hanis, F., E.L.T. Chung, M.H. Kamalludin, and Z. Idrus. 2020. The influence of stable management and feeding practices on the abnormal behaviors among stabled horses in Malaysia. Journal of Equine Veterinary Science 94:103230.