Do you add bacon grease to dog's food? A client said he does it once a week. I am worried about pancreatic problems. Anyone educated in this?

Vet said wrong kind of fat!

Also sodium nitrates as a preservative that can't be good for them (or us).

I don't think once in a while would hurt them maybe as a treat, but I wouldn't do it on a regular basis.

Gee the farmers around here with their dogs feed anything from table scraps to soup. They also feed their dogs LARD, Bacon, eggs, pea, stew , some farmers only feed cheap dog food, and I must say their dogs have good coats, healthy eyes, and are old when they die.
Who really knows.

I'm not sure. I give mine Omega 3 from the vet in capsules.

Some may get what is needed in food.
just seems a shame to give fat from bacon with salt and nitrates. If bacon is not good for us how is it good for our dogs?

I would not give bacon fat. Too much fat can cause pancreatitis.