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