Problem - My horse that I have had almost a year (May 11!) is food aggressive.
Backround info - When we got Splash, he was a little is grumpy towards people when eating hay and especially grain. He would pin his ears, stomp his back feet, and sometimes would charge. He would never bite though.
We treated him for ulcers, because he was in 8 homes since the age of two since we got him (he was 5). The treating of ulcers helped with his working attitude.
Ever since we got Splash, he has had training issues to re-train him in - which is fine, but we waited on the food aggressiveness until he had more groundwork and respect for us first.
We put him on Succeed, a digestive conditioning supplement to help prevent ulcers or anything else like that. This also helped with his temperament.
Splash is a total different horse with his halter and lead on when he is eating. He doesn't care if you are petting him, blanketing, ect. Even with grain.
Over the months, he would get into the habit of "snake heading" at people and biting the air, never people. We would patiently wait for him to stop and then reward him by walking away or praising with pets.
When Splash gets grain or hay my trainer and I always wait for him to perk his ears and stand. This habit has made him less jittery and mad when feeding.
What Splash is doing now - Splash this morning got fed hay, and the man that fed Splash walked to the next horse and fed him too. Everything was fine. The man walked back past Splash's stall and Splash lunged out and bite him in the shoulder. Thankfully the man had a sweatshirt on so he was OK.
Splash is getting worse, when we first got him he only threatened, now he is lunging and biting.