Advocate Flea, Heartworm And Worm Treatment for Dogs. Advocate not only treats parasite infections, but monthly treatment can help protect your dog against fleas, heartworm and most gastrointestinal worms. An easy-to-use spot-on, it is applied monthly. The super ingredients in Advocate provide fast relief from fleas, prevent deadly heartworm and protect both your dog and your family from most gastrointestinal worms. Advocate stops fleas feeding within 3 to 5 minutes, killing adult fleas and their larvae within 20 minutes â€“ breaking the flea lifecycle. With monthly use it also protects your dog from the danger of heartworm infections.