They may keep fleas off a cat's head, but not the rest of the body, and many of them aren't able to kill fleas. How does a dog flea collar work? Pin On Advice Do flea collars actually work? Does flea collars actually work . Sorry, but i speak from experience, those collars simply do not do their job. Flea and tick collars for cats can help manage pesky pests, prevent infestations, and keep your cat healthier. When you put a flea collar on your dog or cat, it releases chemicals that spread along your pet's body through the oils on his fur and skin , according to medicanimal.com. All of them work in essentially the same way however, and that is by simply placing the collar around your dog’s neck. We highly recommend it, and you can get the seresto flea collar on amazon. The worst bit is that these collars only repel fleas around your dog’s neck region. The effectiveness of the flea collar for dogs depends on the type of insecticides used. There are act...