Frontline Spot On Dog protects your dog against ticks for 4 weeks and fleas for 5 weeks to 3 months. After application, Frontline is effective against fleas within 24 hours and effective against ticks or lice inside within 48 hours. Spot On Dog is simply applied between the shoulder blades. Exactly where your dog cannot lick itself. After use, your dog is protected against adult fleas, ticks and biting lice.