So I want to hurt dogmeat to be able to use a stimpak on him. I have him as a follower and shooting him with anything doesn't do anything. I do not have the inspirational perk so that shouldn't be affecting him at all, but I still cannot hurt him at all. I am not sure if there are any bugs possibly related to perk magazines that might be making him invulnerable. Has anyone else run into this? Anything I can do to repair this bug?

No you cant hurt dogmeat. It's not a bug.

Which is a good thing, because I can't tell you how many times I've accidentally killed poor Lydia in Skyrim.

Out of curiosity, though, what's the reason for you trying to do this?

So I can raise the affinity of the followers that like me healing dogmeat.