A charmer of a letter opener I think, with the beaver allowing for a good grip, and making opening the mail feel a little more festive. I love that the blade of the opener feels rather like an extra long tail, and that it is carved of wood, since the beaver is of course the best wood carver of all. I believe it was likely made as a tourist souvenir, and is stamped Lisbourg, for Lisbourg in Quebec, Canada, on the back.
1940s or so I'd guess and in very good used condition. 8" l x 2" w x 3/8" d.