What sort of flea and heartworm prevention do you use?

I usually use Frontline as a flea preventive measure for my dogs and it really works like a charm. You should try it.

Normally for my dog I use Advantage for the fleas and Heartguard for the Heartworms. One thing that is important to remember is that any chemical used repeatedly will cease to be effective. You should have your dog checked for heartworm disease at least once a year to insure that he or she is fully protected. Also, continue to check your dog for evidence of fleas because the flea medications especially will become less effective with overuse. Usually if you switch to a different type of medication for a couple of months you shouldn't have a problem.