It begins as a superficial inflammation followed by sloughing, ulceration, and the formation of fistulous tracts which may involve the tendons, bones, and joints.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
It may lead to necrosis of the bone or a fistulous tract from the bone to the surface.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
Sometimes the skin is indurated and lies in folds, or the shoe-boil shows abrasions on its surface and fistulous openings leading from abscess centres.
"Common Diseases of Farm Animals"
R. A. Craig, D. V. M.