Rabbit

Also known as a pacemaker; this is a horse with no expected chance of winning but is used to prompt a quick pace on the front end of the race to the benefit of a stablemate who is a closer.

Scratch

A horse is a scratch when injury or other necessity causes it to be withdrawn from the race.

Blinkers

A hood worn on a horse’s head to limit side vision, which can improve concentration. Blinkers are added or removed to relax a horse or give it more focus.