Four isolates of Yersina enterocolitica and six of Y. pseudotuberculosis were made from carcasses collected in Ontario in 1973. Y. enterocolitica was isolated from the following species: Canada goose, Branta canadensis (serotype 4,33), Pekin robin, Leiothrix lutea (serotype 6,30), beaver, Castor canadensis (serotype as yet unknown), and raccoon, Procyon lotor (serotype 5,27). Yersiniosis was apparently the cause of death of the beaver and the cause of liver abscesses in the raccoon; the significance of the isolates from the birds was not determined. Y. pseudotuberculosis isolations were from a crow, Corvus brachyrhynchos (serotype 1A), two purple martins, Progne subis (serotype 1B), and three beavers (serotype 1B). Yersiniosis was apparently the cause of abscesses in one of the beavers and the cause of death of the other cases.

During the period from 1962 to 1972, Y. pseudotuberculosis had been isolated in this laboratory from four beavers and one snowshoe hare, Lepus americanus. There was no record of previous isolation of Y. enterocolitica. In most cases, septic abscesses were found in various tissues; however, significant pathological findings were absent in the Canada goose and the Pekin robin. All but the Pekin robin were free-living native animals.