I use ivermectin for any adult hounds. I buy it at a farm store, it is made for horses. You can also order it out of Lion Country Supply, etc. Much more cost effective than heartworm meds from the vet. I buy the liquid, though I think they make a paste, but i'm not sure how you would get the right ratio that way. .1 cc or.1 ml/per 10 lbs of dog. Once every 3 months, prevents heartworms and all worms I believe.
Different wormers work for different worms. For heartworm preventative (you must make sure your dogs does not already have heart worms) you can use ivermectin sold at the farm store. I use the suspension liquid make for cattle and give dogs .10cc per 10 lbs once a month. You can give it orally by putting it on bread or anything they will eat. Lots of times I give mine in a little bit of milk.
For intestinal worms I use safeguard. It has the same active ingredient as popular dog wormers just in a smaller ration of wormer to liquid. The goat formula is the most cost effective. When you give this type of worming it must be done 3 days in a row or it will not work. I believe the ratio i use is 2.4 cc or liquid per 10 lbs of dog. This ends up being quite a bit of liquid for my 50 lb dogs, but I just draw it up in a horse syringe, with no needle, and pushing it down their throat and then hold thier mouth shut till they swallow.
The two wormers will get every worm cost effectively but tapes and that is a whole nother bowl of wax.