The best way to prevent fleas is by using topical preventives. These products, such as ZodiacĀ® Spot OnĀ® Flea & Tick Control products, are highly effective ways to keep your pet from getting fleas. Many topical preventives kill adult fleas with an adulticide, and kill flea eggs and larvae with an insect-growth regulator (IGR). When applied as directed, these products offer easy, powerful prevention.