We don't use Sentinel much where I work. Not only is it a fairly expensive heartworm med (in comparison to Heartgard & Tri-heart with Frontline Plus) but as a flea control it can't match Frontline Plus/Advantage.

With Sentinel the fleas still actually BITE your dog to get the treatment, which still allows for allergic reactions to flea bites. No so with Frontline Plus/Advantage, let alone that Sentinel does not actually kill the adult fleas just a birth control for them. Frontline Plus/Advantage actually kills the adult fleas as well as Frontline Plus ALSO has the birth regulator as well as K9Advantix (although don't use that one in a house with cats)



From Noravitis website (manufacturer of Sentinel)

Treated immature fleas will not be able to molt to the next stage and females feeding on treated animals will produce eggs out of which no larvae will hatch.


Honestly if I had a dog I'd use Tri-heart Plus for heartworm and Frontline Plus for fleas.

As another alternative (although I'm not sure on pricing difference) you could try Revolution which is a Heartworm preventative/flea preventative.

Whatever heartworm medication you get be sure to have your dog tested for heartworm BEFORE giving heartworm preventative!