[Halicephalobus (Syn. Micronema) deletrix as a cause of granulomatous gingivitis and osteomyelitis in a horse].

Therapy resistant swellings of the maxillary region and unilateral nasal discharge in older horses are mainly thought to be consequences of neoplasias of the oral cavity, especially of the gingiva and the teeth, or to develop from tumours of the nasal cavity. We report an unilateral swelling of the left nasal and buccal region in a 13-year-old gelding, which was accompanied by an aggressive destruction of involved osseous tissue due to a severe proliferative granulomatous inflammation. The granuloma was caused by the nematode Halicephalobus (syn. Micronema) deletrix. This nematode infection is known for over 30 years, even though the here reported form is uncommon and rarely diagnosed. However, this report shows that even in cases of unilateral maxillary swellings in horses a granulomatous inflammation due to nematodiasis should be considered as an additional differential diagnosis.