"Okay!"

This one will take a while, he never did it before and it's involved. He doesn't want an ugly skin tail, though, so he starts out by growing a patch of hair at the base of his spine. He has read a bit of his anatomy book, skimmed over most parts, and paid a lot of attention to the most interesting pictures. Bone structure were some of them, since most of the times his transformations hurt happen because of bones squeezing stuff that shouldn't be squeezed.

So the next part is turning the end of his spine into not-quite-an-end, something that will become a tail but is still attached to his hips. He bases off other mammals' tails, and then his starts growing, pushing against his skin as he stretches it and makes more hair grow.

He's not content until his tail is about three quarters as long as he is tall, and that takes a while. About an hour and a half, to be precise. Hopefully Addy is patient, because once he starts he pretty much forgets she exists, and is wholly engrossed and focused in this process.

As for his blood pressure? No variation to speak of.