Age: Puppies have different nutritional needs than adult dogs, and senior dogs have different needs than adult dogs.
Breed: Some breeds are more prone to certain health conditions than others. For example, large breed dogs are more prone to hip dysplasia, so you may want to choose a food that is specifically formulated for large breed dogs.
Activity level: If your dog is very active, he or she will need a food that is higher in calories and protein than a dog who is less active.
Health conditions: If your dog has any health conditions, you will need to choose a food that is formulated for his or her specific needs.
Taste: Your dog should enjoy eating his or her food. If your dog doesn't like the taste of the food, he or she won't eat it, and that won't be good for his or her health.