OBJECTIVE To describe the etiologies, clinicopathologic findings, diagnostic modalities employed, treatments, and outcome associated with cases of septic bicipital bursitis. ANIMALS 9 horses. CLINICAL PRESENTATION AND PROCEDURES Medical records of horses diagnosed with septic bicipital bursitis between 2000 and 2021 were reviewed. Horses were included if synoviocentesis of the bicipital bursa revealed a total nucleated cell count of ≥ 20,000 cells/µL with a neutrophil proportion of ≥ 80%, a total protein concentration of ≥ 4.0 g/dL, and/or the presence of bacteria on cytology, or positive culture of the synovial fluid. Information retrieved from medical records included signalment, history, clinicopathologic variables, diagnostic imaging findings, treatment, and outcome. RESULTS Trauma was the most common inciting cause (n = 6). Synoviocentesis using ultrasonographic guidance was performed in all cases and showed alterations consistent with septic synovitis. Radiography identified pathology in 5 horses, whereas ultrasonography identified pathology in all horses. Treatment consisted of bursoscopy (n = 6) of the bicipital bursa of which 1 was performed under standing sedation, through-and-through needle lavage (3), bursotomy (2), or medical management alone (2). Five (55.6%) horses survived to discharge. Long-term follow-up was available for 3 horses and all were serviceably sound, with 2 in training as pleasure horses and 1 case continuing retirement. CLINICAL RELEVANCE Ultrasonography was the most informative imaging modality and paramount in obtaining synovial fluid samples for definitive diagnosis of septic bicipital bursitis. Bursoscopy performed under standing sedation is a feasible treatment option. Horses treated for bicipital septic bursitis have a fair prognosis for survival and may return to some level of athletic performance.

A horse presented to the referral hospital for pyrexia and unilateral nasal discharge. Computed tomographic examination demonstrated changes consistent with unilateral primary sinusitis. Frontal and rostral maxillary trephination facilitated sinoscopy and lavage of the paranasal sinuses. Postoperatively, subcutaneous emphysema of the head and neck developed and upon further investigation pneumomediastinum and pneumorrhachis were diagnosed on radiographic examination. The trephine portals were the likely entry point of the subcutaneous emphysema; gas then dissected through the fascial planes of the neck into the mediastinum. It is hypothesised that gas also extended along cervical fascial planes and through intervertebral foramina to enter the spinal canal causing pneumorrhachis. This is accordant with cases in human medicine and current understanding of mediastinal anatomy. The horse recovered with conservative management; however, it is noteworthy that pneumomediastinum and pneumorrhachis are potential complications of sinoscopy. Pneumothorax can subsequently develop, which could be life threatening.