If you buy organically raised foods for yourself—for taste, to avoid pesticide exposure, for lower eco-impacts, or all these reasons—you’d probably prefer to go organic for your pet, granted you can afford the premium you may pay.

But buyer beware: The USDA has not yet established official rules for labeling organic pet foods, so on some labels, the term functions more as a marketing term.

“[My coauthor and I] found one brand with ‘organic’ in the name that contained no organic ingredients at all,” Nestle says. “Make sure the company is really committed to organic ingredients.” Better companies go the extra mile to have independent USDA-accredited certifiers verify their products.

Other common pet-food-label terms with no regulatory definition: holistic, which generally refers to a lack of colorants, fillers, byproducts, and unnecessary chemicals; and natural, which usually indicates no artificial flavors, artificial colors, or artificial preservatives.

The FDA does, however, define “human-grade” ingredients: Pet foods using this term will never have byproducts and in some cases, as with The Honest Kitchen’s offerings, may even be produced in a human-food facility, rather than a pet-food factory.

Special diets

Some special pet diets reflect owners’ values as much as or more than animals’ needs, Nestle says. Take vegetarian diets, for example. “These products are absolutely for the owners,” she says. The good news is that you can find nutritionally complete vegetarian options, with protein derived from peas, potatoes, and the like.

Another special-diet trend: raw. “Vets who advocate raw diets believe it emulates what dogs and cats would eat in the wild,” says Parthasarathy. Although raw is a more an expensive choice, proponents swear by anecdotal health benefits, such as shinier coats and higher energy levels.

Most raw diets include bones and some fruits and vegetables; commercial foods are largely animal protein—for instance, Instinct by Nature’s Variety is 95 percent meat, organ, and bone, and completely grain-free.

Ultimately, a common-sense approach is the best way to choose the right food for your pet. First, says Nestle, decide what you can spend; then select a food in that price range that meets your values. “If your pet is thriving, great,” she says. “If not, try another.”

Vitamins for fido

It's an open question whether it's worth investing in pet foods that offer added nutrients such as antioxidants, probiotics, essential fatty acids (EFAs), and glucosamine.

"Studies show the benefits of antioxidants and probiotics on pet health," says Mukand Parthasarathy, PhD, "but is the quantity inlcuded in pet foods enough to make a difference?"

If in doubt, add supplements seperately.

For example, omega-3 EFAs may help clear up skin issues, but the required dose is often higher than can be added to kibble. Because there are no major food sources of glucosamine, pet nutritionist Susan Lauten, PhD, recommends separate supplements for older pets with joint issues.