I have three new brahma cross heifers that seemed to have gotten wormy about six weeks ago so I treated them with Ivomec. They seemed to improve but the scours never fully cleared up and then came back. Treated them again after three weeks and now they seem to have cleared up and are gaining weight. Their coat however is still real messy and not laying down. Can someone please tell me how long it takes for the coat to get smooth after a bout with worms. thanks.