Cribbing collars are used to control cribbing, and are effective in some horses. There are a variety of cribbing collars on the market. Generally, they have two straps. The longer one is the brow band while the shorter one goes over the poll. The throat piece presses gently into the throat of the horse.
When a horse cribs or wind-sucks, they flex and expand the muscles of the throat, causing discomfort as the throat presses against the firm collar. It is this pressure and discomfort that discourages cribbing.
The Weaver Leather Miracle Collar is the product I have used most. My description here applies to that device.
Standing on the left of the horse, buckle the shorter poll strap. Then buckle the browband. Set these so that you can insert 1-2 fingers between the horse's throat and the throat piece of the collar. Monitor the horse for cribbing behavior. If it continues, tighten the straps a notch and again watch for cribbing, but do not apply too tightly.
Tips for safety & Success
Keep in mind that the most important way to prevent cribbing is management changes that reduce boredom and increase socialization. Some horses continue to crib while wearing a cribbing collar. In these cases, talk to your vet about making such management changes.
Cribbing collars that are placed too tightly cause swelling and compression of the windpipe and vessels that run through the area. Visit the manufacture's website for specific instructions on the proper size, fit and adjustment.
Most cribbing collars come in several sizes: small (for weanlings, yearlings and small ponies), medium (for average size horses), and large (for Warmbloods and other larger breeds).