Identifying Behavioral Pain Indicators in Ridden Horses

by Erica Larson, News Editor

Your horse might buck if a bug bites, swish his tail if you give a whip-tap on his haunches, or show the whites of his eyes if he spots a very scary object. But one researcher recently reported that if these behaviors become regular occurrences, especially without provocation, your horse is probably trying to tell you he’s in pain.

In a series of studies over the past few years, Sue Dyson, MA, Vet MB, PhD, DEO, Dipl. ECVSMR, FRCVS, head of Clinical Orthopaedics at the Animal Health Trust Centre for Equine Studies, in Newmarket, U.K., and colleagues developed and validated an ethogram for ridden horses—a catalog of behaviors a horse might display under saddle and what they mean. She designed the ethogram to help identify low-grade lameness or pain in ridden horses.

In her most recent study Dyson compared horse behavior and pain scores before and after diagnostic analgesia (nerve blocks given during a lameness exam) to see if individuals with no specific training on the ethogram could use it to reliably recognize pain in horses working under saddle. She shared the results at the 2018 American Association of Equine Practitioners Convention, held Dec. 1-5 in San Francisco, California.

“Owners and trainers are often poor at recognizing lameness,” especially if it’s subtle, Dyson said. “Performance problems are often labeled as training-related, behavioral, or ‘just how he’s always gone.’

24 Pain-Associated Behaviors

Face

  • Ears rotated back behind vertical or flat
  • Eyelids closed or semiclosed
  • Sclera (whites of the eye) exposed
  • Intense stare
  • Opening mouth repeatedly
  • Tongue exposed and/or moving in and out of the mouth
  • Bit pulling through the mouth, to the left or right

Body

  • Repeated head position changes
  • Head tilt
  • Head in front of the vertical
  • Head behind the vertical
  • Head moving constantly from side to side and/or head tossing
  • Tail clamped or held to one side or large tail swishing movements
  •  

Gait

  • Rushed gait/irregular rhythm
  • Sluggish gait/irregular rhythm
  • Hind limbs not following in the front limbs’ tracks
  • Repeated wrong lead and/or change of lead in front or behind in canter
  • Spontaneous gait changes
  • Stumbling and/or repeated toe-dragging
  • Sudden change in direction of movement
  • Spooking
  • Reluctance to move freely/stopping spontaneously
  • Rearing
  • Bucking with or without kicking out backward

“Horses are trying to communicate with us,” she added. “We need to learn to listen.”

Dyson said the original ridden horse ethogram contained 117 behaviors. In the current study she and colleagues focused on 24 behaviors they identified as most closely associated with pain (see sidebar). She said the presence of eight or more of these markers likely reflects musculoskeletal pain.

In the study Dyson had one assessor trained in how to apply the ethogram and 10 untrained assessors (two veterinarian interns, one junior clinician, five vet techs, and two veterinary nurses) assessors each watch videos of 21 horses ridden in working trot and canter in both directions by professional riders, before and after diagnostic analgesia (42 videos total). The videos were presented in a random order, she said.

“The ethogram was applied in a binary fashion for each behavior: yes or no for the presence of the behavior,” she added.

The study horses had various diagnoses of unilateral or bilateral lameness in the front and/or hind limbs, kissing spines, or sacroiliac pain. Before veterinarians administered the diagnostic analgesia, the trained assessor identified three to 12 (with an average of 10) behavioral indicators of pain in ridden horses, Dyson said. After analgesia, the trained assessor pinpointed zero to six (an average of three) behavioral indicators of pain—a significant decrease in behavior scores, she said.

“The untrained assessors also had significant reductions in behavior scores for all the horses after resolution of pain,” she said.

Additionally, “the reduction in behavior scores verifies a likely causal relationship between pain and behavior,” she said.

Dyson and her colleagues also analyzed agreement among assessors—how often they independently came to the same conclusions about a horse’s behavioral indicators:

  • Agreement was “fair” among the untrained assessors for lame horses;
  • Agreement between the trained assessor and the untrained assessors for lame horses was moderate; and
  • After diagnostic analgesia, there was fair agreement among the untrained assessors and slight to no agreement between the untrained assessors and the trained assessor.

Based on these findings, Dyson concluded that both trained and untrained assessors can use the ridden horse ethogram to identify the likely presence of musculoskeletal pain. However, veterinarians, owners, trainers, and others using it require education on the ethogram for best results, she said.

 

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