weight loss problem????

If you try what Silverton said, then most likely youar having dietary issues.

Do they have bad stools?

If you can't do the Whole raw Diet, which is very important to get more than "just meat" thats why he reccomends the whole hog. Then go to your grocery store and get a couple of 16 oz cans of Jack mackeral. (canned fish) and you can add a couple of fish from the can with some of the juice to their normal portions of feed and see if you son't see a difference in acouple of days.
Canned Fish is cheap or atleast the mackeral is $1.50 per can and will have 6-8 fishes per can, and can do three days off a can per dog just as an additive to their feed. If you see major improvements, then your dogs are not getting enough vitamins & nutrition fromtheir feed, and you need to do something different for their dieteary needs.

If they feel fine but stools are bad and appetite is a little off I would start looking for an intestinal Protazoa or bacteria, but your vet should have checked for that.