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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.

Objective—To determine the effects of hyperbaric oxygen therapy (HBOT) on full-thickness skin grafts applied to fresh and granulating wounds of horses. Animals—6 horses. Procedures—On day 0, two 4-cm-diameter circular sections of full-thickness skin were removed from each of 2 randomly selected limbs of each horse, and two 4-cm-diameter circular skin grafts were harvested from the pectoral region. A skin graft was applied to 1 randomly selected wound on each limb, leaving the 2 nongrafted wounds to heal by second intention. On day 7, 2 grafts were harvested from the pectoral region and applied to the granulating wounds, and wounds grafted on day 0 were biopsied. On day 14, 1 wound was created on each of the 2 unwounded limbs, and the wounds that were grafted on day 7 were biopsied. All 4 ungrafted wounds (ie, 2 fresh wounds and 2 wounds with 1-week-old granulation beds) were grafted. The horses then received HBOT for 1 hour daily at 23 PSI for 7 days. On day 21, the grafts applied on day 14 were biopsied. Results—Histologic examination of biopsy specimens revealed that grafts treated with HBOT developed less granulation tissue, edema, and neovascularization, but more inflammation. The superficial portion of the graft was also less viable than the superficial portion of those not treated with HBOT. Conclusions and Clinical Relevance—The use of HBOT after full-thickness skin grafting of uncompromised fresh and granulating wounds of horses is not indicated.

Objective—To determine whether clinically effective concentrations of methylprednisolone or triamcinolone can be achieved in the navicular bursa after injection of methylprednisolone acetate (MPA) or triamcinolone acetonide (TA) into the distal interphalangeal joint (DIPJ) and whether clinically effective concentrations of these drugs can be achieved in the DIPJ after injecting the navicular bursa with the same doses of MPA or TA. Animals—32 healthy horses. Procedures—Horses in groups 1 through 4 received 40 mg of MPA in the DIPJ, 10 mg of TA in the DIPJ, 40 mg of MPA in the navicular bursa, and 10 mg of TA in the navicular bursa, respectively. Concentrations of corticosteroids that diffused into the adjacent synovial structure were determined. Results—For group 1, injection of MPA into the DIPJ yielded a mean ± SD concentration of 0.24 ± 0.072 μg of methylprednisolone/mL in the navicular bursa. For group 2, injection of TA into the DIPJ yielded 0.124 ± 0.075 μg of triamcinolone/mL in the navicular bursa. For group 3, injection of MPA into the navicular bursa yielded 0.05 ± 0.012 μg of methylprednisolone/mL in the DIPJ. For group 4, injection of TA into the navicular bursa yielded 0.091 ± 0.026 μg of triamcinolone/mL in the DIPJ. Conclusions and Clinical Relevance—A clinically effective concentration of methylprednisolone or triamcinolone diffused between the DIPJ and navicular bursa after intra-articular or intrabursal injection, which would justify injection of the DIPJ with MPA or TA to ameliorate inflammation of the navicular bursa.