Tough economic times haven’t taken a nip out of the natural and organic pet food business: Sales hit $1.3 billion in 2010, according to Nutrition Business Journal. And the products on offer go way beyond kibble and cans—from raw frozen meals and novel ingredients for the allergy prone (emu, sweet potatoes) to added nutrients (omega-3s, antioxidants) and virtuous label claims (organic, vegetarian, even human-grade).

“Manufacturers typically look at trends in human foods,” says Mukund Parthasarathy, PhD, a pet-food industry columnist and consultant to companies formulating products. “We want our pets to follow our own healthy lifestyles.”

Choosing the right food can be a complex equation, combining cost, personal values, and your animal’s unique health issues.

As a baseline, all pet foods labeled “complete and balanced” meet the standards of AAFCO (Association of American Feed Control Officials), an industry trade group that mandates minimum requirements for protein and key nutrients. Beyond that, there is little research to commend one food over another.

“Some ingredients certainly sound better than others, but there’s no comparative research, so it’s really a matter of faith,” says Marion Nestle, PhD, professor of nutrition at New York University and coauthor of Feed Your Pet Right (Free Press, 2010).

Shoppers should look at what’s important to them, Nestle says. Organic ingredients? Few or no grains? Vegetarian options? Your preferences may have as much to do with values as with nutrition, but once you know what you want, Nestle says, buy the best product you can afford.

Read labels for problem ingredients

“Get the product with the simplest ingredient deck possible, especially if your animal has problems with allergies,” says Susan Lauten, PhD, a pet nutritionist based near Knoxville, Tenn.

Allergies can manifest as itchy skin, ear infections, even chronic diarrhea. With a short-and-sweet list, it’s easier for you to know what your pet is eating and to eliminate problem ingredients for sensitive pets.

Though certain grains, especially rice, can be a great source of nutrition, grain-free products that supply carbohydrates from vegetable sources are often an excellent option for sensitive pets. “Look for food that does not contain commonly identified allergens such as wheat or wheat gluten,” says Edward Moser, DVM, a consultant for Wellness Pet Food.

Some pets also develop allergies to common protein sources, especially chicken and beef. (Soy can also be allergenic, so is best avoided, says Moser.) Many companies now use more unusual animal proteins, including lamb, ostrich, venison, and bison, which may be easier to tolerate. It can take a week or more on a new diet to notice changes.

Should your pet eat organic?

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.