I don't know if you are dealing with a horse who has canker or just curious about it, but I thought I would share.
I just came back from my mailbox with a new issue of Horse Sport magazine, in it, in the news section was a brand new product that treats canker. I remembered seeing a question on the horseforum about canker and just thought I would let you know about it.
It is called Purple Mush Hoof Packing. It is made by Well-Horse. It is a 100% natural salve. In tests it was found to resolve even the most severe cases of canker in 2 weeks.
The cost is $100/hoof for the standard size, $200/hoof for the large size. It includes instructions, a glove and enough packing product to conduct 2 five- day hoof packing treatments.
Website is Well-Horse Natural and Organic treats Horse Wounds, Horse Skin Fungus, Horse Thrush, Horse Laminitis, Founder, Rain Rot, Scratches