Every horse owner is familiar with the ubiquitous flexion test, which veterinarians regularly employ to exacerbate baseline lameness and reveal unknown internal issues in horses. No standard duration, however, dictates how long veterinarians should hold the limb in the flexed position. Researchers recently tested the results of comparative full hind limb flexions held for five seconds and for 60 seconds in order to assess the viability of shortening the time commonly spent applying flexions.
Limb flexions are subjective in nature; the application of the flexion test and the interpretation of the results vary between veterinarians. Warren Beard, DVM, MS, Dipl. ACVS, professor of equine surgery at Kansas State University's College of Veterinary Medicine, noted that the practitioner performing the test must take into account the duration of flexion, force applied during flexion, and age and use of the horse.
During the study researchers used videos of lameness examinations of 34 horses that ranged from completely sound to very lame. The exams included a 60-second proximal (upper) hind limb flexion and a five-second flexion of the same leg.
A panel of 15 equine clinicians reviewed one video recording of the baseline lameness paired with the five-second flexion and another of the baseline lameness paired with the 60-second flexion to evaluate the degree of lameness each horse showed during each flexion test. The recordings were edited to show only the last two seconds of flexion followed by the trot segment. The clinicians were unaware of the aim of the study, and a random sampling of 10 of the cases were repeated for evaluation.
Upon reviewing the panel's evaluations, the team found that practitioners on average were in agreement on about 75% of the cases when interpreting horses' response to flexion. In addition, degree of lameness after flexion for five seconds and 60 seconds was interpreted the same 74% of the time.
"This is actually fairly good for subjective data," remarked Beard. In the cases in which discrepancy was noted, the 60-second flexion yielded greater positive (meaning lameness was evident after the limb was released) interpretations.
"While different practitioners will not necessarily agree on what constitutes a positive response to flexion, each practitioner achieves reasonably consistent results," Beard explained. "Interpretation of the response (i.e., degree of lameness) to flexion between five and 60 seconds is very similar."
Essentially, the researchers found that flexion for five and 60 second yielded similar results, indicating that one duration isn't necessarily "better" than the other.
"We advise practitioners that choose to abbreviate their flexion examinations to perform their own trial to feel comfortable that they are not altering their decision-making progress," Beard concluded.
This study, "A comparative study of proximal hindlimb flexion in horses: 5 versus 60 seconds," is slated to be published online an upcoming edition of the Equine Veterinary Journal. The abstract is available online.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.