The main problem with fly repellents is they dont last all night. This especially effects sweet itch horses which are most vunrable at dusk. So unless you going to get up rediculously early your horse will be unprotected.
Now avaliable on the market are Gels and Wax products which do appear to last longer but not all night.
Another problem is if your horse sweets or theres a shower the repellent just washes off and again unprotected.
A few products have come out on the market wearing the repellent which gradually releases the repellent over time giving your horse protection, they are usually waterproof and protect upto 90 cm away.
Here at FLY-OFF we have this type of repellent with a new deisgn which combines an internal resivour with impregnated rubber to release the repellent accordingly. They are also adjustable strentgh.