I think feeding your dog salmon is a little excessive!...Spoiled!
You can look up what kind of things a dog shouldn't have on the interenet. I know they should never have chocolate because it is a poison to them. Also, dairy is not good for your dog in excessive quantities. If your dog has a tummy ache or upset stomache then it is ok to give them a little yogurt or milk but not on a regular basis; it should almost be used as a medicine or petobismal type thing.
I don't think you need to go as far as switching your dogs diet to people food and making it three meals a day; that's a little too much! But definately introducing different types of fruits and veggies as treats once and a while would be good for the vitamins and nutrients. If you want more information you can cunsult your vet and see what their opinions/suggestions are.