I have an 11 month old Greater Swiss Mountain Dog who has been food aggressive with unpredictability. We have worked with our breeder and a highly skilled trainer, he has done board and train and he has been home with us for three weeks now. In the last week he has acted out twice (he is chained to a doorframe while we train/ feed him so that he cannot get to us). Outside of feeding he is a bit intense when he sees new dogs or when people come over and I would classify his intensity as excited and friendly. Asides from meal time with a bowl, he has never shown aggression. We can hand feed him treats, feed him treats on the ground and hand feed him his kibble without incident.

Tonight he was panting before I fed him, and while I fee him, at one point he was struggling to chew and pointed his head up while struggling. This lasted for about 30 seconds and I proceeded to feed him according to our training program. Once the food was gone, I went to close a Tupperware container and he lunged at me for about 30 seconds. I did not react, demonstrated pacifying signals and waited for him to stop. Once he stopped, he looked at me without aggression for about 20 seconds and when I picked up his bowl he then proceeded to lunge at me again for another 30 seconds. The whole ordeal lasted under two minutes and then he paced, sniffing the ground.

In total he ate 4.5 cups of food today, which is about average for his breed and age.

My question is- has anyone come across any health issues that would lead to this behaviour?

Any suggestions are welcome.