Razor X have you had a bad experience with the injections? I put my dogs on a pro heart injection for heart worms about 4 years ago. The shot is given every 6 months and seems to work great. My older lab had heart worms while on heart guard chewables and had to be treated. I live in mosquito country and the vet said heart guard was not working very well. I was kind of forced into the injection from lack of other options but so far so good.
I've never used Pro heart 6 but I've heard of a lot of people who did have problems with it. I didn't think it was still available. If it's working for your dogs and you've had no problems by now, then I would just stick with what us working.
