Raw salmon is essentially considered to be poisonous for dogs because of the fact that it could contain the parasite which is known as nanophyetus salmincola. Those who own dogs should avoid giving their pets raw salmon at all costs because of the inherent health threat which it poses for them.
If you must give your dog salmon, make sure that it is thoroughly cooked so the threat of parasites is reduced as much as possible. It is also acceptable to give your dog salmon oil, mixing it in with their food. Overall though salmon is one of the foods that is considered to be toxic and potentially poisonous for dogs.