Stationary jump tests demonstrate potential as objective return-to-sport outcomes based on hind limb symmetry in healthy dogs

Objective: To improve testing methods to develop clinically applicable return-to-sport assessments in dogs by evaluating hind limb push-off symmetry while jumping onto a platform from a stationary position. The hypothesis was that normal dogs would demonstrate > 90% symmetry when performing the newly proposed jump tests. Jump tests included sit-to-withers-height jump, stand-to-head-height jump, and stand-to-withers-height jump with side rails. Methods: This was a prospective, methodological study in which orthopedically and neurologically normal dogs were asked to jump onto a platform, performing 5 valid trials of 3 separate jump tests within a 30-minute period of time. Peak vertical force of the hind limbs was measured and expressed as a percentage of symmetry for each trial. Results: 20 dogs were included. The mean percentage of symmetry for each jump test variation was as follows: stand-to-head-height jump was 83.27% (SD, ± 5.20%), stand to withers with side rails was 73.49% (SD, ± 12.63%), and sit-to-withers-height box was 67.39% (SD, ± 20.96%). However, when selecting for each dog's best attempt, symmetry was 96.90% for stand to head height, 92.34% for side rails, and 94.39% for sit to withers height. Conclusions: Dogs were less than 90% symmetrical in the hind limbs when averaging 5 valid trials for each jump test. An unexpected finding was that when evaluating for each dog's best attempt, hind limb symmetry was above 90% for all modifications. Clinical Relevance: The development of easy-to-perform, reliable, and repeatable return-to-sport assessment tests could provide objective data on canine recovery from orthopedic and neurologic injury.