Merhorse Test only
A test only (render stopped at 20% to see where problems might be.
This is just a Daz fabric shader, I think if it was a proper texture it would look better (that way you could control the direction of the scales) but I think i worked out how do the iridescence by using this shader. They have a rainbow type image in the top coat. (I think you'd see it better if I had chosen different lighting). I used a tail I had for G2F and just tried to make it work.