Necrotising fasciitis in a bull due to infection with Arcanobacterium haemolyticum.

ABSTRACT

CASE HISTORY A 2-year-old Hereford bull was lame for one week before becoming recumbent. CLINICAL AND PATHOLOGICAL FINDINGS: The scrotum and ventral perineal region were cold and blackened caudally. The semimembranosus and semitendinosus muscles were firm on palpation. The bull was subject to euthanasia, and necropsy revealed that the skin and S/C tissues of the caudal half of the scrotum were grey and necrotic. The caudal and distal aspects of the semimembranosus and semitendinosus muscles were grey and necrotic to a depth of approximately 15 cm, and these changes appeared to track along fascial planes. The tissue had an offensive smell, and large amounts of flocculent, watery, brown fluid and some gas were present. Histology of affected muscle and S/C tissues revealed coagulative necrosis, with oedema and large numbers of bacteria that were predominantly Gram-positive rods. Adjacent blood vessels contained thrombi while the epidermis overlying the affected areas appeared diffusely necrotic, suggesting infarction. Culture of the fluid yielded a pure growth of Arcanobacterium spp., which was identified as Arcanobacterium haemolyticum, using an API Coryne biochemical test strip. DIAGNOSIS Necrotising fasciitis and myositis due to Arcanobacterium haemolyticum. CLINICAL RELEVANCE Arcanobacterium haemolyticum has not previously been reported as a cause of necrotising fasciitis in any species. Necrotising fasciitis is probably an under-reported condition in cattle due to its clinical similarity to clostridial disease.