Salmonella is not an issue for many dogs -especially dogs fed raw food - but for puppies and immuno-compromised animals, it -can- be an issue.
Dogs that have been fed kibble or low-quality kibble and only one type of it, for years - can also be sensitive to food-based illness because they don't have good gut health. Here's an article discussing how salmonella, diet, bacteria and gut health are connected: http://www.thewholedog.org/salmonella.pdf