Confining the animal in a small stall and tying it with too short a halter strap favors a sternal position when lying down.
"Common Diseases of Farm Animals"
R. A. Craig, D. V. M.
5 and 6. The origin is from the anterior edge of the sternal portion of the first three thoracic ribs.
"Thoracic and Coracoid Arteries In Two Families of Birds, Columbidae and Hirundinidae"
Marion Anne Jenkinson
Variations found in these vessels were the following: In one specimen of S. inca the sternal artery had, on both sides, an independent origin from the subclavian, lateral to the origin of the coracoid artery.
"Thoracic and Coracoid Arteries In Two Families of Birds, Columbidae and Hirundinidae"
Marion Anne Jenkinson