Dogs can wear collars for extended periods, but experts recommend against leaving them on for too long. Many vets suggest removing your dog's collar after every walk or at bedtime to avoid skin irritations and pulling. However, you should weigh the benefits and safety risks of taking off your dog's collar before you let him go for too long without it. Talk to your vet about how long you should leave a collar on and schedule a visit if your dog experiences any collar irritation.