All pets age differently, depending on size, breed, lifestyle choices, diet, and environment. Even though she may seem young in your eyes, your dog aged 7 and older, or your cat aged 11 and older, is considered a senior. To keep your senior pets vibrant into old age, consider the following steps: Fine tune their dietEvery pet needs a wholesome diet, but aging pets need more care than youthful ones. Elderly pets need more protein than younger pets. The more digestible