Provides 8-months of continuous flea and tick prevention Seresto flea and tick collar for large dogs works through contact, so fleas and ticks do not have to bite your dog to die Veterinarian-recommended flea and tick prevention for dogs in a convenient, odorless and non-greasy collar; No need for messy monthly treatments Starts to repel and kill fleas within 24 hours of initial application Flea and tick collar for large dogs also helps treat and control sarcoptic mange and kills lice