Combination heartworm, roundworm, flea medication

Boxer mom here, too! My vet stopped selling Frontline Plus after a lot of clients complained about it not working anymore. They now sell Frontline Tritak, the next generation of the drug, I guess. I works for my dogs so far. I'd love to use Sentinel (also endorsed by my vet), but it doesn't kill ticks, so I passed on it. I use Heartgard Plus for Heartworm prevention.