Use of serial standing computed tomography for diagnosis, treatment and monitoring of a horse with acute myonecrosis of the head

An 11-year-old American Quarter Horse gelding was referred to the JT Vaughan Large Animal Teaching Hospital at Auburn University, College of Veterinary Medicine, for investigation of acute and severe right-sided facial swelling and nasal discharge. Standing computed tomographic (CT) examination of the head identified severe soft tissue swelling surrounding the right mandible, emphysema within the soft tissues tracking along fascial planes and right-sided caudal and rostral maxillary sinusitis. Using CT identification and ultrasound guidance, several targeted fasciotomies were created into the right masseter, cranial cervical musculature, supraorbital space and caudo-medial aspect of the mandible. The right-sided sinusitis was treated by right conchofrontal sinus trephination and lavage. Aerobic and anaerobic cultures obtained from the fasciotomy sites and conchofrontal sinus both yielded Prevotella intermedia and Peptostreptococcus asaccharolyticus. During hospitalisation, serial, standing CT examinations were performed for monitoring case progression and guiding further fasciotomies in the face of continued myonecrosis. Follow-up CT performed at 1 month showed resolution of the emphysema and presence of chronic right ventral conchal sinusitis. The sinusitis was treated by fenestration of the right ventral concha with a diode laser via the nasal passage.