OP,
I actually ~tried~ an animal communicator once, but not for my horse. This was long before I got my mare. It was for a dog that I was having really serious issues with, and who was later diagnosed with rage syndrome. I was somewhat desperate at the time.
While I was on the phone with the communicator about the dog, the cat came to the door and sat down and started staring at me. I didn’t really notice this until out of the blue, the communicator said “DON’T GET ANOTHER CAT!”
Cat?? We were talking about the dog. I hadn’t told the communicator I EVEN HAD a cat. Then I looked and saw her sitting there, staring at me.
The cat had aparantly told her that she didn’t want another cat in the house with her. The house was sort of all over the place with the issues surrounding the dog, and the cat thought that another cat would make it worse, not better.
This would probably not mean much, and could have come from anything, except that about a week before, I was in the office at home and the house was empty except for me and the cat. I had asked the cat: “Do you want a friend? Do you need an ally, someone who would be on your side against the dog?”
Aparantly, the answer was no.
And–
In response to this thread, I looked up Lydia Hiby on her website and I bought a used copy of her book on sale, and while I was reading the part on dogs, my little fuzzy lap-size dog Maddie, who is generally very independent, climbed up and sat with me. But the instant I reached the “Cats” chapter, she was gone! LOL
And–
I might call Hiby after my mare’s “join the family day” party on Halloween. So I can ask what she thought about the party. I’ve got all the non-horsy family coming! I have plans, but won’t say anything more… 
According to the website, Hiby only charges $40 for 15 minutes. It might be fun!