NexGard Chewable Tablets For Dogs are a monthly treatment for dogs that kill fleas and ticks. The active ingredient in NexGard, afoxolaner, works by absorbing quickly into the dog’s bloodstream and disrupting the nerve transmission in fleas and ticks. This causes paralysis and death in fleas and ticks. NexGard is available in four different sizes for dogs of all sizes. The chewable tablets are beef-flavored and easy to give to dogs.