Management of Subchondral Lucencies of the Medial Aspect of the Equine Antebrachiocarpal Joint.

The objective of this study is to describe the management and outcomes of eight horses with subchondral lucencies (SCLs) of the medial aspect of the antebrachiocarpal (ABC) joint. The medical records and radiographs of the carpi of 8 horses with SCLs of the medial aspect of the ABC joint were reviewed. Follow-up clinical information was obtained for 6-60 months (the median duration of 14 months). Treatment was successful if radiographic healing was apparent or lameness was reduced or eliminated. Four horses had SCLs in the distomedial radius (DMR) and four in the proximal aspect of the radiocarpal bone (RCB). Lameness was present in all horses with DMR SCLs and in one horse with an RCB SCL. Treatments included restriction of exercise (n = 3), intra-articular administration of corticosteroids (n = 2), or placement of a screw across the SCL (n = 3). Exercise restriction alone was successful in three nonlame horses younger than one year with proximal RCB SCL and intra-articular corticosteroid administration in the ABC joint in two horses aged 2 years or younger with DMR SCLs. A yearling with a large proximal RCB SCL and two horses aged 5 years or older with DMR SCLs were successfully treated with screw placement across the SCL. Exercise restrictions and intra-articular administration of corticosteroids were successful in management of DMR SCLs in five horses. Placing a screw across the SCL of three horses resulted in resolution of lameness and substantial improvement of the radiographic appearance of the lesion in the RCB or DMR.

Subchondral lucencies of the proximal tibia in 17 horses.

OBJECTIVE: To describe subchondral lucencies (SCL) in the equine proximal tibia, several treatment options, and clinical outcomes. STUDY DESIGN: Retrospective study. ANIMALS: Seventeen horses with proximal tibial SCL. METHODS: Medical record and radiograph review. Follow-up was obtained via examination and radiography when possible and by telephone and race records when required. The median duration of follow-up was 20 months (range, 0-48). RESULTS: Proximal tibial SCL were associated with lameness in 14 of 17 horses. Subchondral lucencies were primary in 11 horses and secondary to an ipsilateral medial femoral condyle SCL in six horses. One foal with a primary SCL was euthanized because of osteomyelitis. Six horses ≤1 year old with primary SCL were managed with exercise restrictions only; SCL in three horses without lameness decreased in size, whereas three horses with lameness did not improve. One young horse treated with surgical debridement failed to improve and was euthanized. Lameness resolved in three horses with primary tibial SCL treated with screw fixation. Screw fixation of secondary SCL in five horses led to a reduction in SCL size and degree of lameness. CONCLUSION: Primary tibial SCL healed with rest in 3 non-lame young horses with small SCL, but was not successful in lame horses with larger SC. Radiographic size and associated lameness improved or resolved with screw fixation in primary and secondary proximal tibial SCL. CLINICAL SIGNIFICANCE: Primary tibial SCL that did not cause lameness healed with conservative management, but persistent primary and secondary tibial SCL required screw fixation to reduce lameness.

Macrolide- and rifampin-resistant Rhodococcus equi on a horse breeding farm, Kentucky, USA.

Macrolide and rifampin resistance developed on a horse breeding farm after widespread use was instituted for treatment of subclinical pulmonary lesions in foals. Resistance occurred in 6 (24%) of 25 pretreatment and 8 (62%) of 13 (62%) posttreatment isolates from affected foals. Drug-resistant isolates formed 2 distinct genotypic clusters.