Petfood ingredient labels can be confusing to pet owners because certain terms have no legal definition. Ernest Ward, veterinarian and founder of the Association for Pet Obesity Prevention, says pet owners need to do their research when selecting what to feed their dog or cat.

Ward says there is no official definition for the term "natural," which could mean anything that is not synthetic but does not guarantee the product's quality or nutritional value. Another term often found on petfood labels is "organic." This refers to how plants were grown or animals were raised. The US Department of Agriculture's National Organic Program provides standards for human organic foods, which require at least 95% of ingredients be in compliance to have the USDA seal on the package; this applies to petfoods, too. Petfood consumers may also look for this seal on the labels of organic petfoods. The label "grain-free" on petfood packages means that they do not contain grain, wheat, corn or animal by-products.

Consumers must also understand how petfood is regulated, Ward says. The Association of American Feed Control Officials establishes nutritional standards for petfood, while the US Food and Drug Administration regulates petfood and its labeling.

Ward says pet owners should look for petfoods that contain the highest amount of protein that is minimally processed. When petfood ingredients are heated, Ward explains, much of the food's nutritional value is lost, and petfoods with a high amount of carbohydrates do not offer much nutritional value, either.