Removing a tick from a horse can be tricky -- particularly for the squeamish. This disease-carrying insect has a strong jaw that anchors it to its host; thus, during removal it's easy to leave the tick's head embedded in the skin, inviting infection.
Several commercial tick-removal devices are available, but a simple technique recommended by the American Lyme Disease Foundation, Inc. also works: Using splinter forceps or tweezers, grasp the tick as closely to the skin as possible and gently pull it straight out. Don't worry if the ticks' mouthparts are left in the flesh; they should not cause a problem. After removing the insect, apply an antiseptic to the site.
For less immediate but equally effective results, swab the tick in both directions with a cloth soaked in baby oil or rubbing alcohol. This suffocates and kills the tick, but it may remain attached to the horse for hours or even days before falling off.