Yes, you can put a collar over Seresto. The Seresto collar is designed to fit comfortably under the pet’s collar, so it’s easy and comfortable for the pet to wear. However, some pets may require special collars—such as escape-resistant collars for cats with a knack for getting out of their collars—so if your pet does need an alternative collar, be sure that it fits snugly over the Seresto collar too. Also, take care to make sure the alternative collar isn’t too tight as this could cause skin irritation or limit the effectiveness of the flea and tick protection provided by Seresto.