Can't make out the picture properly, seems to be a man hitting a dog with the a rifle butt. I hope I'm wrong...:S
that is not a canadian stamp as that appears to be photo edited. the style of the border of the stamp reflects back to the 1950's or earlier
http://www.gan.ca/images/articles/seal_clubbed.jpg I believe that this image was used on a selection of fake postage stamps back in the Eighties. They were used by a group who regularly tested the Canadian Post Office's delivery standards. The spoof stamps were supposed 'proof' of the low standards inasmuch as the mail was delivered without sufficient postage. The 'Seal Clubbing' motif is a staple of animal welfare groups in fund raising.