he may just be nervous with the striking the dog's smell / seeing him may make him nervous and cause to strike. Most recommend covering the cage and keeping the other animals away from the cage if this is happening... As for the staring, mine do that...boas are curious and will watch you, etc. It does not necessarily mean he is aggressive.

If you don't already have one, I would get a small snake hook and start hook training him. When you need to move him, clean the cage, etc. always rub him with the hook first, then use it to pick him up. Once out of their cage, most boas aren't as defensive. You can also use the hook as a buffer between your hand and his head... i.e. put the hook between his head and where your hand is working so that he can't strike you. Only use the hook when handling / cleaning. Never use the hook when feeding, that way, he will not associate it with being fed and should not strike.