I covered this on a previous blog but I think it is always worth discussing again. There is no specific requirement for “senior pet foods.” I know that may be a bit tough to read but AAFCO (which is the organization that determines feeding requirements for different stages of a pet’s life) has not published any recommendations for our senior pet’s diets.
Therefore, most of the senior diets you see out there is all marketing. They are formulated to be fed to a dog over 1 year of age and a lot don’t have anything special in them to make them senior-specific. There are a couple notable exceptions: Hill’s Senior Vitality and Purina Bright Minds. These products actually are specifically designed for the issues that our senior pet’s face and they are what I recommend to any person looking for a senior pet food.
So, the short answer is yes; “senior” pet food can be fed to any dog over a one year old. I think the most important thing is to speak with your vet about necessary nutrient restrictions in senior pets. For example, phosphorus can be damaging to the kidneys so it is paramount that you control phosphorus in the diets of senior cats with kidney disease. When in doubt, talk with your vet and they can help you choose the most appropriate food.