Factors influencing recovery from and duration of lameness in Michigan (USA) horses

Expert visual assessment strategies for equine lameness examinations in a straight line and circle: A mixed methods study using eye tracking

BACKGROUND

A large number of lameness indicators have been suggested for the visual equine lameness assessment. However, it remains unknown which of these are commonly used by experts.

METHODS

Twenty-four expert lameness assessors from 10 leading UK institutions viewed 28 video clips of sound and mildly lame horses (median score 2/10). Horses were shown at trot in a straight line (rear and front view) and circle (side view, left and right rein). Eye tracking data were collected at 60 Hz while participants evaluated each clip. A questionnaire captured contextual information.

RESULTS

During assessment on the straight line, participants consistently looked mostly at the head and pelvis. On the circle, many participants consistently looked at the head, yet the subsequent choice, weighting and order of examined body regions was unsystematic between and within participants, and there was a bias towards prolonged assessment of the horse's front region. Questionnaires revealed different descriptions of lameness indicators for the same body region and different approaches to decision making under uncertainty.

CONCLUSION

In contrast to reasonably high similarity on the straight line, expert veterinarians have not developed a consistent assessment approach when evaluating horses on the circle. The reliability of various lameness indicators on the circle requires a stronger evidence base for a more systematic, repeatable approach.

The effect of trotting speed on the evaluation of subtle lameness in horses

Equine lameness is a significant and challenging part of a veterinarian's workload, with subtle lameness inherently difficult to assess. This study investigated the influence of trotting speed on perceived and measured changes in movement asymmetry. Ten sound to mildly lame horses were trotted at a 'slow', 'preferred' and 'fast' speed on a hard surface, both on a straight line and in a circle on left and right reins. Video recordings of the horses were visually assessed by six experienced equine clinicians. Vertical movement of head, withers and pelvis was derived from inertial sensor data and several features calculated. On the straight line, more horses were subjectively declared sound at higher speeds, whilst different objective asymmetry measures showed only slight and inconsistent changes. On the circle, speed had no significant effect on the subjective assessment, with an increase in objectively measured asymmetry at higher speeds possibly balanced by a decrease in sensitivity of the observers for this asymmetry. Horses visually examined for subtle lameness on the straight should therefore be evaluated at a slow speed. Trotting speed should be consistent on repeated occasions, especially during objective gait analysis on the circle, to avoid the interaction of treatment effects and speed effects.

Lameness and poor performance in horses used for team roping: 118 cases (2000-2003)

OBJECTIVE

To determine the types of musculoskeletal problems that result in lameness or poor performance in horses used for team roping and determine whether these problems are different in horses used for heading versus heeling.

DESIGN

Retrospective study.

ANIMALS

118 horses.

PROCEDURE

Medical records of team roping horses that were evaluated because of lameness or poor performance were reviewed to obtain information regarding signalment, primary use (ie, head horse or heel horse), history, results of physical and lameness examinations, diagnostic tests performed, final diagnosis, and treatment.

RESULTS

Among horses evaluated by lameness clinicians, the proportion with lameness or poor performance was significantly greater in horses used for heading (74/118) and lower in horses used for heeling (44/118) than would be expected under the null hypothesis. Most horses examined for poor performance were lame. A significantly greater proportion of horses used for heading had right forelimb lameness (26/74 [35%]), compared with horses used for heeling (7/44 [16%]). Horses used for heading had more bilateral forelimb lameness (18/74 [24%]), compared with horses used for heeling (4/44 [9%]). Horses used for heeling had more bilateral hind limb lameness (3/44 [7%]), compared with horses used for heading (0%). The most common musculoskeletal problems in horses used for heading were signs of pain limited to the distal sesamoid (navicular) area, signs of pain in the navicular area plus osteoarthritis of the distal tarsal joints, and soft tissue injury in the forelimb proximal phalangeal (pastern) region. Heeling horses most commonly had signs of pain in the navicular area, osteoarthritis of the metatarsophalangeal joints, and osteoarthritis of the distal tarsal joints.

CONCLUSIONS AND CLINICAL RELEVANCE

Horses used for heading were most commonly affected by lameness in the right forelimb. Horses used for heeling had more bilateral hind limb lameness than horses used for heading.