Tucker and I are taking a 16 week beginner agility course. Our first class was this Tuesday, and I have to say I was a bit embarrassed. Tucker does very well with following close to me and sitting and staying etc. one on one, but he seemed to have a really hard time keeping his focus around the other dogs.
We have been divided up into four groups, by dog size. Tucker is in with a Havanese, a boston terrier, and a Cavalier King Charles Spaniel. Tucker did fine with everyone except Finn, the Boston Terrier. Everytime they were within a couple feet of each other Tucker starts barking and lunging at him.
What can I do? I tried waving a favorite treat in front of him and he doesn't even care.

I'm afraid we will be kicked out of class if he doesn't behave.