An excellent value from the K9 Advantix brand K9 Advantix Extra Large Dog 30-day treatment & prevention protects dogs over 55 lbs. from fleas, ticks, mosquitoes, biting flies, and lice Affordable formula works on contact to kill and repel fleas on dogs within 12 hours of application even without a bite Easy-to-apply topical treatment is fragrance-free and waterproof after 24 hours No prescription needed