In the horse, the ulna and fibula are almost, but not quite, lost.
"The Old Riddle and the Newest Answer"
John Gerard
The ulna is an elongated flat bone.
"Common Diseases of Farm Animals"
R. A. Craig, D. V. M.
"In most quadrupeds, as in ourselves, the forearm contains distinct bones called the radius and the ulna.
"Thomas Henry Huxley; A Sketch Of His Life And Work"
P. Chalmers Mitchell