title: Mycobacterium ulcerans infections in two horses in south-eastern Australia.
abstract: Two horses were diagnosed as having Mycobacterium ulcerans infections. The first was a 21-year-old Quarterhorse-cross mare living in Mallacoota (a coastal town near the border of New South Wales and Victoria, Australia) that presented with lichenification, hair-loss and oedema on a fetlock, which subsequently ulcerated, as well as a non-healing ulcer on the wither. The second horse was a 32 year-old Standardbred gelding from Nicholson, near Bairnsdale, Victoria, that had an ulcerated lesion on its caudal thigh. Histologically, there were characteristic changes seen with M. ulcerans infections in other species, including extensive necrosis without associated granulomatous inflammation. The organisms were seen in Ziehl-Neelsen-stained smears or sections of the lesions from both horses and were isolated in culture from the first horse. A definitive diagnosis was provided by real-time polymerase chain reaction targeting the M. ulcerans-specific insertion sequence, IS2404. Delayed identification of the infectious agent in the first case led to the use of suboptimal antimicrobial therapy, resulting in failure to control the infection and the horse was subsequently euthanased. The second horse was successfully treated following surgical debulking of the centre of the lesion and one session of aggressive cryosurgery. Mycobacterium ulcerans should be considered in the differential diagnosis of unexplained lichenification with oedematous and ulcerated skin lesions in horses living in regions where this organism is endemic.
authors.affiliation: Main Street Veterinary Clinic, Bairnsdale, VIC, Australia.
authors.forename: A
authors.initials: A
authors.lastname: van Zyl
authors.forename: J
authors.initials: J
authors.lastname: Daniel
authors.forename: J
authors.initials: J
authors.lastname: Wayne
authors.forename: C
authors.initials: C
authors.lastname: McCowan
authors.forename: R
authors.initials: R
authors.lastname: Malik
authors.forename: P
authors.initials: P
authors.lastname: Jelfs
authors.forename: C J
authors.initials: CJ
authors.lastname: Lavender
authors.forename: J A
authors.initials: JA
authors.lastname: Fyfe
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D003131:Combined Modality Therapy / Q000662:veterinary; D017809:Fatal Outcome; D005260:Female; D006734:Horse Diseases / Q000175:diagnosis* / Q000188:drug therapy / Q000601:surgery; D006736:Horses; D008297:Male; D009165:Mycobacterium Infections, Nontuberculous / Q000175:diagnosis / Q000188:drug therapy / Q000601:surgery / Q000662:veterinary*; D019911:Mycobacterium ulcerans / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013021:South Australia; D016896:Treatment Outcome; D014739:Victoria
chemical_list: D000900:Anti-Bacterial Agents