Mandibular osteomyelitis caused by Actinomyces denticolens in a horse

Summary

A 3‐year‐old Welsh Cob gelding presented for evaluation and treatment of a recurrent and increasing left‐sided mandibular swelling. A definitive diagnosis and treatment strategy for mandibular osteomyelitis caused by Actinomyces denticolens was achieved using computed tomography examination, bacterial culture and molecular identification. Treatment included ultrasound‐guided surgical debridement, lavage and long‐term antibiotic treatment using an effective antibiotic with good penetration to bone. The horse responded favourably to the treatment, and no relapse was reported after 10 months follow‐up. The finding proves that A. denticolens can infect and cause treatable facial osteomyelitis in horses.