Febrile and severe diarrhea broke out in foals 3 to 6 months of age on 2 Thoroughbred breeding farms in the Hidaka district of Hokkaido over a period of July to September, 1981, after a heavy rainfall. Of 22 foals on these farms, eleven suffered from the disease, and 4 of them died. In a bacteriological survey, Salmonella was isolated from the feces of eight of the 11 diseased foals, and from several organs, including the intestine, of a died one. Those isolates were identified as S. typhimurium from their antigenic structure. From their biotype and phage-type, they were identical with 26bi (Duguid et al.) and 1/19/23/29/31/36/48 (Gershman), respectively. The O and H agglutination tests were performed with the serum of those foals and mares on the two farms and apparently healthy horses on several farms in which the disease had not been found before. A high titer of agglutinin was demonstrated in the serum of the foals affected and apparently healthy mares on the two farms, but not in the serum of the horses on any other farms. S. typhimurium was also isolated from 2 meadow-rats caught in a shed where the affected foals were raised. Therefore, it seems that S. typhimurium may be disseminated widely among the horses and their environment in the Hidaka district.
