Foxtail-induced ulcerative stomatitis outbreak in a Missouri stable

Twenty of 25 horses in a well-managed Missouri boarding stable were diagnos ed with gingivitis/stomatitis. Gross examination of the affected horses rev ealed varying degrees of gingivitis ranging from mild periodontal swelling to marked swelling and erythema with ulceration and hemorrhage. Fine hair-l ike material was embedded within the intensely affected areas. Gingival bio psies from 4 affected horses contained pyogranulomatous inflammation with, in some cases, numerous eosinophils and several grass awns in cross and lon gitudinal section. Numerous foxtail seed heads were identified in hay sampl es. Examination of the records revealed that all of the affected horses had been fed the suspect hay, with the exception of I horse. Although not deli berately fed the suspect hay, this horse did have access to the hay when tu rned out into the exercise paddock. The lesions resolved following a change in hay source.