This is a real photo. What is it, you ask? Well, we had to do a lot of investigation, asking a dozen vets, and only when we went to the most seasoned farriers did we find someone who had seen it before.
This is what we came up with:
Prior to this picture, this horse had suffered from significant canker. That issue was eventually controlled, and the “normal” canker tissue growth was no longer present in the sulcus. (NOTE: Canker tissue looks like goopy cottage cheese and ultimately overtakes the sulcus and clefts. )
We believe, however, that the abnormal (excessive) keratin production found a new path. Instead of growing under the horn and bottom of the foot, in the anaerobic environment canker prefers, it funneled the tissue grow out the back of the sulcus. The result is fascinating.
This horse was sound and the “horn” did not cause any pain. The horn was firm and substantial. Every 6-8 weeks it needed to be cut off, only to start growing right back again.
This mystery is only marginally solved, so we’d love to hear from you if you have encountered something similar!
PS: Sorry if we ruined your concept of a Unicorn