Thousands of hours of horse observations behind new Equine Discomfort Ethogram

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A catalogue of 73 behaviors that point to physical discomfort in horses has been laid out by two equine specialists, who have dubbed it the Equine Discomfort Ethogram.

Catherine Torcivia and Sue McDonnell, both with the University of Pennsylvania School of Veterinary Medicine, say the new ethogram is based on decades spent evaluating the behavior of normal and physically uncomfortable horses in a referral hospital.

Their aim, they said, was to promote an unambiguous universal understanding of equine discomfort behaviors associated with various body systems and anatomic sources.

“Pain and discomfort behavior in horses tends to be especially subtle,” the pair noted in the open-access journal, Animals.

These behaviors are not readily or widely appreciated even by equine professionals, including many long-time horse keepers, trainers, and even by veterinarians, veterinary technicians and care staff, they said.

The pair noted a growing need for a comprehensive ethogram of discomfort behavior in horses, particularly for use in recognizing physical discomfort in domestic animals.

A clear understanding of the physical discomfort behavior of horses among caregivers, trainers, and professional health care personnel is important to animal welfare and handlers, they said.

“This is particularly relevant to pain management for hospitalized equine patients.”

Torcivia and McDonnell acknowledged that various pain-scale scoring guides have been published, typically incorporating only a few classically cited pain behaviors that, in many cases, are specific to a particular body system, anatomic location, or disease condition.

A consistent challenge in using them in practice, and especially in research, is the difficulty in interpreting the listed behaviors, they said.

They said their ethogram comprises a relatively comprehensive catalog of behaviors associated with discomfort of various degrees and sources.

It comprises a total of 64 specific discomfort behaviors grouped into 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.

Some behaviors have slight variations in form, such as stretching, resulting in a total of 73 entries.

Each entry includes a common English term for the behaviour, a definition, a line drawing depiction, and (with one exception, sipping water) a link to a supplemental video file depicting one or more examples of horses displaying the behavior.

The ethogram arises from an inventory of discomfort-related behaviors observed in horses compiled over 35 years of equine behavior research and clinical consulting to medical and surgical services at the university’s equine hospital, mostly by McDonnell, the lead author.

“This research and clinical work included systematic evaluation of thousands of hours of video-recordings, including many hundreds of normal, healthy horses, as well as hospitalized patients with various complaints and/or known medical, neurologic, or orthopedic conditions.”

As the pair noted, in most cases, a source of physical discomfort was eventually diagnosed in thousands of horses, providing important feedback on observed discomfort‐related behaviors.

Each of the 73 ethogram entries is named, defined, and accompanied by a line-drawing illustration. Links to online video-recorded examples are also provided, illustrating each behavior in one or more hospitalized equine patients.

The pair said they believed their ethogram comprises a relatively complete catalog of behaviors that can be used as a reference to recognize discomfort in horses, both for general husbandry and for clinical veterinary assessments.

“Hopefully, it will also prove useful for research and for future pain scale development or refinement.”

Torcivia and McDonnell acknowledged that recognition of discomfort in a prey species such as the horse is particularly challenging.

“Horses have evolved to show little evidence of discomfort or disability in the presence of predators, including humans. This obviously can confound discomfort assessment.”

This phenomenon, they said, was conspicuous in their clinical monitoring of video streams of horses in care.

“When assessing discomfort in horses, it is important to observe remotely. Regardless of how well‐trained a caretaker may be in behavior observation, if discomfort behavior is interrupted by their presence, information regarding the horse’s condition is lost.

“We would not,” they continued, “consider a single occurrence of any one behavior to be conclusive evidence of discomfort.”

When viewing video of a horse to assess its comfort level, in most instances they considered the first occurrence of a potential discomfort behavior as an indicator to continue watching for repetitions.

“Before making a judgment about the causes of a behavior, or what a specific behavior might indicate regarding discomfort, it is important to be sure that it was not an isolated event with an alternate explanation.”

They stressed that their ethogram was based on observations of stalled horses at rest.

“It does not necessarily address discomfort behaviors that may be observed in horses during work,” they said, noting the pain ethogram for horses while being ridden, developed by researcher Sue Dyson, and published in 2018.

“Further, and importantly, our ethogram is not meant to be independently diagnostic, but rather to provide additional detailed information to veterinary professionals.

“Should routine caretakers or health care professionals observe behavior suggesting discomfort, further veterinary diagnostics are indicated.”

Work with about 50 graduate students, veterinary students, veterinarians, horse owners, and trainers indicated that they could successfully apply the ethogram with only a few hours of experience with the technique.

“This ethogram, unambiguously describing equine discomfort behaviors, should advance welfare of horses by improving recognition of physical discomfort, whether for pain management of hospitalized horses or in routine husbandry,” they said.

The paper, which can be accessed here, provides the full catalogue of behaviors, with an illustration, a description, and a link to each of the videos.

McDonnell is the founding head of the vet school’s Equine Behavior Program. She has a particular research interest in equine physiology, behavior and welfare. Torcivia is with the Havemeyer Equine Behavior Lab and Clinic, part of the university’s school of medicine. The illustrations were her work.

Torcivia, C.; McDonnell, S. Equine Discomfort Ethogram. Animals 2021, 11, 580.

The study, published under a Creative Commons License, can be read here.

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