Ive never had a flea problem using revolution but I also never had a flea problem when I used advantage. I just started using the revolution instead because it had the heartworm. I didnt get a heartworm test on mine before using it because they had been on heartworm preventative before that and also I buy it online I dont get it from my vet. I dont know if My Vet would have required it. He would require that they have a heartworm test now before he gave them heartworm meds since I havent been buying from him |