Like most medical professionals, Dr. Traits needs to keep reference material on hoof. However, this is somewhat problematic in his case, as being a wanted stallion makes it rather difficult to visit a library or bookstore. His solution was simple enough: he's been filling one of his notebooks with his own sketched references.

Out of universe, drawing this was something of a bitch, as the anatomical reference I was initially using had some glaring errors. I originally thought it was out of veterinarian's reference book, but upon discovering that several bones were completely omitted, I rather hope it wasn't.