New Ethogram Describes 70+ Discomfort Behaviors in Horses
A newly published, “catalog” of equine discomfort behaviors could help veterinarians, researchers, stable managers, and owners “speak the same language” when it comes to recognizing possible signs of discomfort in horses, according to researchers in the University of Pennsylvania’s School of Veterinary Medicine.

Based on 35 years’ worth of observations of thousands of horses going through various states of health-related comfort and discomfort, the new ethogram—with more than 70 entries—is a veritable “dictionary of discomfort in horses,” said Sue McDonnell, PhD, an equine behavior specialist at the University of Pennsylvania’s New Bolton Center, in Kennett Square.

“What sorts of things do horses do when they’re uncomfortable?” she said. “That’s what we aimed to define in a more or less complete inventory list, to make sure people really understand these discomfort behaviors.”

The list also serves as a visual resource that practitioners and owners alike can turn to for guidance when considering discomfort in horses, said Catherine Torcivia, VMD, also of the New Bolton Center.

“One of our main goals with this ethogram was to get a collection of these (discomfort) behaviors and provide very specific descriptions, with images and videos, which I think are key for people to see what we’re talking about,” Torcivia said. “And hopefully this can kind of bring everyone together as far as what they’re looking at and how they’re interpreting things, just to help them use the same language and get them on the same page when they’re discussing equine discomfort.”

35 Years, Thousands of Horses, Tens of Thousands of Hours of Footage

McDonnell and Torcivia examined footage from video monitoring of horses admitted to the New Bolton Center over the past three and a half decades, since McDonnell’s arrival at the center. Some horses had medical, neurologic, or orthopedic problems, but others—mainly breeding animals and those recruited for research—were apparently healthy and pain-free.

The scientists had at least 24 hours of nonstop video for each horse they evaluated, providing for tens of thousands of hours of behavioral assessment data of healthy horses and those experiencing various kinds and levels of discomfort. Video monitoring is critical, since Torcivia’s earlier study revealed that horses tend to reduce their display of discomfort behaviors by about 77% in front of hospital staff, and about a third stopped displaying the behavior altogether. “Remote monitoring of horses is really important to get the full range of what’s happening with that animal,” said Torcivia.

To complete their ethogram, the scientists also drew from descriptions of discomfort in horses in scientific literature dating back to the mid-20th century, they said.

The Most Comprehensive Equine Discomfort Ethogram To Date

Equipped with such detailed information, the team developed a comprehensive ethogram that not only lists every known behavior horses show in association with discomfort but also provides thorough descriptions, illustrative drawings, and video links.

The 73 entries—including variations on the 64 main discomfort behaviors they describe—comprise eight categories: posture and weight‐bearing; limb and body movements; head, neck, mouth, and lip movements; attention to area; ear and tail movements; overall demeanor; altered eating or drinking; and vocalizations/audible sounds.

The ethogram covers all the behaviors previously described in scientific studies—including recent equine behavior-based pain scales such as the Composite Pain Scale. “Because of our decades of focused behavior work in a veterinary research and clinical setting, our ethogram included additional discomfort behaviors that we did not find in that search (of previous scientific literature on equine discomfort behavior),” said Torcivia.

The study and ethogram, including illustrations, was published by the scientific journal Animals and is available online.