Carr & Day & Martin® Killitch Lotion. Carr & Day & Martin® Killitch Lotion is licenced and proven to prevent and treat sweet itch in horses and ponies. Killitch Lotion contains the active ingredient benzyl benzoate in a soothing lotion that has been specially formulated for horses. Killitch Lotion treats and soothes affected areas. Carr & Day & Martin® Killitch Lotion can be used as a preventative measure in early spring before symptoms become evident and it is possible that the condition may not take a hold.