Discussion

Barnett T.P., Dixon P.M. and Barakzai S.Z.
Aims: DDSP has been reported following LP, and has been associated with continued poor performance and respiratory noise. This study aimed to characterise DDSP diagnosed following LP in a group of post LP horses, and compare it to previously reported forms of idiopathic intermittent and persistent DDSP. Methods: The owners/trainers of horses undergoing LP at one institution were contacted to determine patient progress, and the willingness for re-examination. The horses included were examined at rest, walk, trot and canter with an over-ground endoscope in place. Exercising speeds were recorded. Videos of horses with DDSP were reviewed to determine the frequency and duration of DDSP at each gait and association of swallowing with DDSP. Results: Seventeen of 37 horses examined were diagnosed with DDSP during dynamic examination, and 5/17 also had DDSP at rest.

There was no difference in the percentage of total time spent displaced at each gait (23-28%, P = 0.665). Lower frequencies of DDSP events were seen at the walk compared to the trot (P = 0.03) or the canter (P = 0.05). The majority of horses displaced repeatedly throughout each gait. DDSP was usually induced spontaneously, and if corrected, replacement always followed swallowing. The maximum speed achieved was 8.3 m/s. Conclusions: DDSP seen following LP appears to be induced at lower speeds than intermittent DDSP, resolves and recurs repeatedly, and is not always present at rest. The increased frequency of DDSP events at faster gaits appears to result from increased resolution and re-displacement, with a higher frequency of swallowing observed at these gaits. Practical significance: Horses undergoing LP appear susceptible to DDSP, which appears to differ in its presentation from idiopathic DDSP previously described, and likely reflects an alternative aetiopathogenesis.