I have been using Seresto collars for years
I have been using Seresto collars for years on my dogs. I have never had a problem with the collars. I love that I can put them on my pups in the spring and they last through the fall. I recently had one of my dogs lost for 2 nights, running through grassy fields. When we found her she had approximately two dozen DEAD tics on her. They were super easy to pull off with tweezers.