Worming Dogs

I also posted this in the Parasites:Rx Drugs Against parasites before I found the proper thread... We have a puppy that weighs 55lbs. We had him on trifexis that covered intestinal and heart worm and fleas but he kept throwing it up so he's off that now and we're looking into something else. The vet suggested heartgard but I see that's simply Ivermectin and Pyrantel. My question, can I just buy those two medicines separately in a suspension and give him the dose based on his weight each month instead of paying big bucks for Heartgard? And what do you guys recommend we add for flea control? Thanks! Tweet