Make your dog’s health and comfort a priority with the long-lasting protection of the Seresto Large Dog flea and tick collar. Unlike other flea and tick protection, Seresto Large Dog flea and tick collars are vet-recommended, stocked by 8,000 vet clinics,* and have been trusted by pet owners for nearly a decade to successfully kill and repel fleas for eight continuous months. The Seresto Large Dog collar works to kill pests on contact within 24 hours of application, eliminating them before they bite your dog or lay new eggs. Seresto Large Dog collars are for dogs at least 7 weeks old. Seresto Large Dog is a trademark of Elanco or its affiliates. *Elanco Animal Health, data on file