I have dogs in my yard that keep getting attacked by flys and I clean muy yard every day.. I just don tknow what to do any more

Use insect control devices to get rid of them. Get sticky insect sensor cards or sticky traps to pull flies and small insects from your garden and save your plants as well as your pet.

(better late answer, than no answer?)

I don't know any dogs, i.e. don't know much about flies that attack dogs, but...

You say you clean the poop out daily. Cover the cans? Great, that is 90% of the battle, I believe. But to really find your answer, you should take a couple of the offending flies to an authority, usually the local agricultural extension office and get an ID. That way the critter's life cycle can be determined and you can remove the source of the problem.

There is the face fly, but I am not sure if that species bothers dogs. They are common in cattle and horse environments. Face flies require fresh cattle or horse manure for development.

Is your dog getting bit? Do you live near a stable or cattle ranch or own horses? Do you have a compost pile? Throw grass clippings in there? Stable flies, also called dog flies, are a biting problem for dogs, people and livestock: http://edis.ifas.ufl.edu/ig133 Stable flies breed in hay, grass clippings, and manure.

(I know most of the bugs that bite me, but I can't remember when I have been bit by a stable fly.)