Or at least that is what the instructions say. I've taken to trying to clip the hair in the area I'm going to apply it. The idea to make sure it hits the skin instead of just wetting down the hair. I'm not convinced it's doing my dogs much good. Thus I rely on the "Proban" part of Sentinel for the fleas, and pick off the ticks.

It's important to remove the ticks preferably within 24 hrs. That's how long it takes on average for a tick to attach, and through its saliva enzymes to be able to tap into the dog's circulatory system- and spread any tick borne disease. Tweezers at the base of the tick's head with a sharp pull will get them off. I always give my puppies a treat afterwards and tell them a "bug" was on them. I even show them the "bug". They usually look intently at it.

Note: Some ticks can cause "tick paralysis" where the neurotoxins they inject can cause paralysis of the dog's hind legs. This condition resolves within 24-36 hrs of tick removal.