She has a lot of [free] tips for logo creation and also has pre-made logos to help give you ideas. My bosses referred me to her when we were talking about our company logo and how it was purchased (copyrights and all) from the woman. You can see our logo here
in the header.
Your biggest challenge will be making it simple; a lot of logos with horses use the silhouette; it's very simple and, even though it's overused, still has potential to pack a punch in the right hands.
Your best option would be to talk to a variety of artists. Each one has something different to bring to the table (as far as style, clarity, and experience). Get two or three artists to make various sketches, take them to the barn, and show them. See what the other workers think and then go from there on the logo. I would suggest purchasing the logo and the copyrights so no other company can have that specific logo, and the artist will have no rights to sue you if the company makes commercial products (like shirts) to sell to the public.