Compressive damage to the deep branch of the lateral plantar nerve associated with lameness caused by proximal suspensory desmitis

Objective - To describe pathologic changes in the deep branch of the lateral plantar nerve (DBLPN) of horses determined to be lame because of proximal suspensory desmitis (PSD), and to report the outcome after treatment by excision of a segment of the horses' DBLPN. Study Design - Retrospective case series. Animals - Adult horses (n=16). Methods - Horses determined to be lame on one or both pelvic limbs because of PSD were treated by excision of a segment of the DBLPN, and 30 nerves were examined histologically. Owners were contacted to obtain information about the horses ≥6 months after surgery. Results - Histologic changes suggestive of chronic nerve compression were identified in both nerves of 11 bilaterally lame horses and in the lame limb of 5 unilaterally lame horses. The nerve of the sound limb of 2 of 3 unilaterally lame horses that had bilateral nerve resection also had histologic changes compatible with nerve compression. Ten of 16 horses (62.5%) with follow-up information returned to soundness after excision of the DBLPN. Conclusions - Pathologic changes of the DBLPN associated with compression may complicate PSD of the pelvic limbs. Excision of the nerve may resolve lameness caused by PSD. Clinical Relevance - Horses lame because of PSD of the pelvic limb may remain lame after desmitis has resolved because of compression of the DBLPN. Excising a portion of this nerve may resolve lameness.