Definition:

A horse that is balky, refuses to go forward, refuses jumps, refuses to leave the barn or go into the show ring is said to be sour. Often a horse will be soured because it is over-faced or uncomfortable.

Also Known As: Ring sour, barn sour

Examples: They ran their horse in barrel races so often that it became ring sour. (Although I used barrel racing in this example, a horse can be soured doing any particular sport.)