Being in rescue for years I think I have seen just about everything on the market. I haven't seen the collars do anything but make dogs sick. I use Frontline or Advantix on my dog along with Heartgard. I wish I did not have to use any of the poisons but short of never letting the dog out of the house or spraying them repeatedly with the essential oils , like every time they go out , I have to. I have seen what fleas and heartworm can do to dogs. The thing is do your research , Never use ivermectin on a collie type dog, yes I know there are people who have but in my mind better safe then sorry. Know what symptoms to look for if your dog has a reaction. I buy my things online which saves some money. And I do have a small dog now but when I was also paying for my daughters 2 big dogs and her cat it got really pricey.