I am referring to MY own experience. I've had pets my entire life and I've NEVER used heartworm/flee preventive (in pill form). My cat will be 19 years old this year (September) and up until last year she's been an indoor and outdoor cat. I get her heartworm tested every 2-3 years ($25) and she's never had a single heart worm or crazy flee/tick problem. My Yorkies are house doggies unless I take them where I go. I use natural preventives and it works great. To each their own.
