I sincerely doubt that there is enough salt in a dry dog food to see the salt crystals on the food. If that were the case salt would be in the top 5 ingredients on the label. There are many, many additives to both human and animal food that appear to be white crystals. (Citrates, potassium chloride, sulphates, etc.)

Your Mom is right, Chicken can be a source of salmonella.