There was considerable gluteal atrophy on the affected side.
"The Electric Bath"
George M. Schweig
This condition involves the heavy gluteal muscles and may occur as a complication of azoturia, or a lameness of the hind limb that is usually due to a spavin.
"Common Diseases of Farm Animals"
R. A. Craig, D. V. M.
By flexing the limb and making pressure from below upwards in the gluteal fold, the smooth, rounded prominence can usually be detected.
"Manual of Surgery Volume Second: Extremities--Head--Neck. Sixth Edition."
Alexander Miles Alexis Thomson