An outbreak of ulcerative stomatitis due to mouse barely (Hordeum murinum) in horse

Stomatitis and gingivitis were diagnosed in twenty-six of 96 horses at a club in Mashhad, Iran. Clinical examination of the affected horses revealed varying degrees of ulceration at the gum-tooth margins with many awns (seed heads) embedded in ulcers. The ulcers were painful, up to 5 cm in diameter, and located at the labial-gingival junction, the lingual frenulum, the base of the lingual dorsum, soft palate, and the sides of the tongue. The evaluation of feed ingredients which had been fed to the affected horses showed contamination of alfalfa hay to mouse barley (Hordeum murinum) seed heads. After removal of the contaminated hay from the ration, the ulcers healed slowly over about 3 weeks.