I don't purport to be an expert in any of this in any sense of the word, but have an interesting note.

I have PTSD and have not found animals to be directly helpful in particular. I enjoy spending time with them and they make me happy, I enjoy the process of caring for them but don't find them to be therapeutic necessarily .

However, I've noticed an immediate calming effect when handling my snake. He totally chills me out. I had a typical PTSD nightmare for me this morning and got up to handle him and it really helped. I haven't had that feeling with an animal before. I don't know what that's about but just something to note. Everybody experiences things differently. I think that's the therapeutic feeling others have experienced. That doesn't mean I'm going to take him everywhere or anything but just thought I'd share.