I tried cowboy magic and didn't like it at all! Maybe my goldens are hairier than yours, but it made them greasy and the smell was overwhelmingly floral - maybe on a horse it smells better? Blagh! I used show sheen on my horses ages ago - good product, works well on dogs, careful of the surfaces you use it on (makes hardwood slippery!).
I love love love love (emphasis) the Chris Christenson Ice on Ice product - I buy the concentrate - I use it weekly most of the year and bi-weekly to keep them untangled during swim season...
I second the oil adding though, we do cold-pressed coconut oil and salmon oil caplets, both are digestible and well tolerated.
Erica