This is an Aussie recipe for sand colic. it works a treat and brings the coat up all shiny by next day. Not all horses will 'drink' it. You could mix it in with chaff, or dose with a syringe (which is messy and takes ages but is better than a refusal).
The only rules are; natural, non processed, non supermarket honey. you need it fresh from the apiary or a country store. I don't know why exactly but it's something to do with the enzymes that are killed when honey is heat treated and blended and super-marketed.
In a heavy base pan, heat gently without boiling; 500g honey, 600ml full cream milk, 200ml full fat cream.
Allow to cool. Feed to horse.
One dose per year, any weight, any breed.
I swear by it.