Response to injection of the navicular bursa with corticosteroid and hyaluronan following high-field magnetic resonance imaging in horses with signs of navicular syndrome: 101 cases (2000-2008).

OBJECTIVE: To determine treatment outcome on the basis of pathological changes identified on MRI and lameness duration in horses with navicular syndrome that underwent injection of corticosteroid and hyaluronan into the navicular bursa.

DESIGN: Retrospective case series.

ANIMALS: 101 horses with navicular syndrome.

PROCEDURES: Medical records of horses with signs of navicular syndrome evaluated between January 2000 and December 2008 were reviewed. Data on signalment, use of the horse, history, affected limbs, duration of lameness, findings on lameness examination, radiographic findings, MRI findings, treatment, and outcome were collected from the medical records. Follow-up information was obtained a minimum of 10 months after navicular bursa injection.

RESULTS: Following navicular bursa injection, 76 of 101 (75%) horses returned to their intended use for a mean of 9.66 months, and 35 (35%) were sound at follow-up. Horses that had been lame for < 6 months before treatment were significantly more likely to return to their intended use, have a longer positive response to treatment, and be sound at follow-up, compared with horses that had a longer lameness history. Horses with primary deep digital flexor (DDF) tendonitis responded best to navicular bursa injection with rest and rehabilitation, followed by horses with navicular bursitis and horses with DDF tendonitis and adhesions to the collateral sesamoidean ligament of the distal sesamoid (navicular) bone. Horses with scar tissue in the proximal portion of the navicular bursa, adhesions from the navicular bone to the DDF tendon, or multiple abnormalities did not respond as well to treatment.

CONCLUSIONS AND CLINICAL RELEVANCE: Response to navicular bursa injection with corticosteroid and hyaluronan in horses with navicular syndrome was dependent on the disease process detected on MRI and duration of lameness.