According to a recent survey commissioned by Iams, 11% of pet owners consider age to be the most important factor when determining what food to buy their pets.

There are three basic lifestages dogs and cats fall into, though precise ages vary between species and among breeds: kitten and puppy, 1 to 12 months; adult, 1 to 7 years; and senior, 7 years and older. "When choosing a food for your cat or dog, it is important to select a diet that has the right ingredients for that stage of your pet's life," said Katy Nelson, DVM, member of the Iams Pet Wellness Council. "Diet requirements – including protein levels, calories and vitamins and minerals – vary over the life of a pet and, in turn, an animal's needs change as he grows from a puppy or kitten, to an adult into a senior."

According to the survey, other factors pet owners consider most important when choosing food are ingredients (30%), expert advice (36%) and price (25%).