Mackin said these assumptions are not necessarily accurate, and choosing a pet food should be based on what the animal likes, its health needs and the veterinarian's approval. If convenience or cost means you choose supermarket brands, that doesn't make you a bad pet owner because most pets can thrive on whatever commercial feed you give them. Premium pet foods are different from special veterinary diets or prescription diets designed to prevent or treat illnesses. Premium foods have contents guaranteed by strict quality control. These usually cost more, but price alone does not determine premium brands.
Some brands cost more because of high marketing costs.
The bigger the company is and the longer it has been in business, the more likely it is to have good quality control. Quality control refers to the guaranteed nutritional value given by certain ingredients provided in set amounts. Less expensive brands guarantee minimum nutritional standards, but not ingredients. For example, corn may be substituted for rice as a carbohydrate if market prices are lower for corn. Premium brands usually use the same ingredients, regardless of price.