Salmon is a healthy protein for dogs. Protein makes up the building blocks of each structure in the body such as muscles, tissue and nerves. Feeding a range of proteins is vital to cover for all the required amino-acids (single units of proteins) a dog needs.
Salmon is perhaps best known for its high levels of the essential fatty acid, omega 3. Omega 3 is vital and classed as 'essential' as both dogs and humans must obtain it from their diet as it can not be made by the body.
Essential fatty-acids have many roles, including controlling inflammation; they also make neurotransmitters (brain chemicals) and hormones. The omega 3 contained within salmon can help to support joint and bone issues, helping to reduce inflammation and improve brain function.
Salmon is also a source of vitamin A and D which promote correct cellular replication and immune function. Many supplements on the market sell salmon oil to aid arthritis but you can't beat obtaining nutrients from whole foods and feeding salmon can be a way of obtaining valuable omega 3.
I don't advocate the feeding of raw salmon due to parasites and bacteria so always best to cook; fish oils are easily damaged so a light steam is best. Fillets are a useful way to avoid bones. Avoid smoked salmon as it is high in sodium. Canned salmon is perhaps fine in moderation as it is a super source of vitamin D (mash the bones) but again comes with a downside of toxins which come from canning. Organic fish is hard to find considering our waters are becoming toxic but wild-caught fish could be considered as a better choice in comparison to farmed fish which is pumped full of antibiotics and chemicals. Atlantic salmon is typically farmed while Pacific salmon species are primarily wild-caught. Wild salmon eats shrimp and krill which gives salmon its red colour due to astaxanthin (an antioxidant) and perhaps an indicator of quality.