You can also try http://health.centreforce.com.
It's located in Australia, and the black salve is called Centerforce black salve, but only a veterinary version is available. It's the same formula as original Cansema Salve, in fact, it's labeled as Centerforce Cansema. The ingredients are: Gallangal, Chapparal, Bloodroot, Zinc Chloride, and DMSO. The only difference between the version available and that originally mean for humans is that it's not so strong on the first application and has more DMSO to help penetrate thicker animal skins. I've used it on four spots and one can feel it burn a bit at first, more of a hot tingle. It seems to do the trick.