Advantage Multi is a topical that gets all the same critters as Trifexis, at a few dollars cheaper per month. Since it's a topical, it's less convenient (you get the greasy, stinky spot on the shoulders for a few days). It's quite effective, as long as you take care to apply it to the skin (not the hair).
In your area up North, do you need flea protection year round? If not, since HW is needed year round everywhere according to AHS, why not separate them? Use a good flea stuff in the warm months only (FYI, Vectra 3D is getting rave reviews from friends, and it gets ticks too, which Adv. Multi and Trifexis don't).
Then pick a heartworm preventative -- you could do the 6 month injection (Proheart 6) for convenience, or use Heartguard or a generic equivalent all year long (e.g., Iverhart Max has the same ingredient to prevent HW (ivermectin) as Heartguard, and it's $28/6 pills at KVsupply.com; Pet Trust is another generic for Heartguard that costs $30/6 pills at local Walmart pharmacies). Compare that to around $90/6 months for Advantage Multi from KV Supply, and you'll save a chunk of change by not wasting money to treat fleas that aren't around during the winter.
Last edited by Magwart; 05-28-2014 at 07:03 PM.