A vesiculo-bullous disease in pigs resembling foot and mouth disease. II. Experimental reproduction of the lesion.

Vesiculo-bullous dermatitis of pigs characterised by presence of vesicles and bullae on the snout and feet of white skinned pigs was reproduced experimentally. Leaves of parsnips (Pastinaca sativa), or celery (Apium graveolens) infected with the fungus Sclerotinia sclerotiorum were fed or rubbed on the snouts and feet of white skinned pigs. Pigs were then exposed to sunlight or to UV light of intensity approximately 212 m W/M2 at a wavelength 340-360 nm for eight hours per day until vesicles developed. All treated pigs developed lesions on the snouts, and less frequently on the feet. Lesions were characterised by the appearance of erythema at 24 hours after treatment. Vesicles developed at 48 hours and became maximal by 72 hours. Pigs treated with plant material without exposure to UV light or exposed to UV light without contact with plant material did not develop lesions. The experimental lesions closely resemble those observed in several field cases in 1984 and 1985 in New Zealand and to lesions present in three well publicized foot and mouth disease scares at Warkworth, and Temuka in New Zealand and Legana in Tasmania.