Has he just started doing it?
If so look at what you're doing differently and stop doing it before it becomes a habit
The only other thing is to try one of the various collars on the market and see which one works for him and spray anything he cribs on with something non toxic/non caustic but foul tasting
I always thought this too but evidently it is not necessarily so. A vet that does a lot of scoping for ulcers says that most horses that come for examination because they are cribbers do not have them.
This made me curious and I called a few vets and all said th same.
Cribbing is one of the sterio typi behavior, or vises, that mainly begin out of stress of confinement. Once established, very hard if not impossible to stop, so the solution then is to use a cribbing collar.
Surgery is controversial , although this article shows it to have very favorable results How Effective is Cribbing Surgery? | TheHorse.com
Ulcers, or course, are also related to stress, so very likely some of the same factors that cause cribbing, also cause ulcers (confinement), thus both seen in the same horse, but that does not indicate that ahorse cribs, due to ulcers
It is better to practice the 'oz. of prevention is worth alb of cure"!
Is he actually cribbing or just chewing on the wood? I have a gelding who chews on wood when I don't give him enough minerals. If I see him starting again I'll give him a bowl of loose minerals and let him supplement as he sees fit. That always stops him. Have you tested to see if he has any mineral deficiencies?
Definitely confirm that he is, indeed, cribbing and not just chewing on the wood. These are very different behaviors with very different causes and solutions
There appears to be a genetic component to cribbing, with some lines of horses more predisposed to cribbing than others. Horses that crib almost always start in response to stress of some sort (the stress could be a result of ulcers/digestive discomfort or stall confinement, but cribbing is not at all limited to horses with these problems). About half of cribbers start at weaning.
I've heard of people stopping cribbing behavior if it's caught right after they start, but once it's established, I'm pretty sure it's impossible to stop. I've tried pretty much every solution out there with my gelding (collars, omeprazole, 24/7 turnout, etc.) but nothing has really helped much. With 24/7 turnout he seems to crib less, but I still see him off by himself cribbing quite often.
When I purchased my horse, he had a long (several days trailer ride having not been in a trailer much was so nervous and distraught he had to be sedated to take the edge off his behaviour so as not to injure himself, damage the trailer or upset the others he was travelling with. Long story short when he stepped off the trailer he was a bag of nerves and immediately took to chewing the fences- badly! I tried no- chew spray/ hot peeper mash painted on, suppliments and salt etc the only thing that seemed to deter the habit was irish spring soap rubbed on the board edges until he settled in. He will still grab a board if he gets nervous which isn't often at all now.