Dewormer is a good idea. Flies are awful around here. Caused me lots of Vet bills, in thier eyes crawled under a fly mask somehow, and the sheath , habronema's .. Karo syrup on feed.. horses Love it. Just a small squirt adds flavor and they slurp it up. Even the skinny old brood mare who Just knows that we are poisoning her with additives .LOL.. she detest any substance on her feed but karo syrup helps hide the bute taste and smell , for when she needs it. Also, try teasing her with the supplements, leave it just outside her pen , where she cannot reach it, but give the neighboring horse its feed. So she will Want hers.