“This foot isn’t going to look pretty and be comfortable to her,” McGann tells Cowboy State Daily, pointing at a deep notch in the hoof.
The cuticle was damaged in an injury and, just like fingernails, likely won’t ever grow back correctly. It's dangerous because the notch could catch on something and tear up the horse's entire hoof, so it has to be trimmed.
McGann's goal, as with all the horses, is minimal intervention.