WEDNESDAY, Sept. 22 (HealthDay News) -- Pet owners need to be aware that natural foods aren't always the best choice for their pets, says a Kansas State University veterinarian.

"Natural and veggie-based pet foods are based more on market demand from owners, not because they are necessarily better for the pet," Susan Nelson, an assistant professor of clinical services, said in a university news release.

She noted that dogs and cats have specific nutritional needs that may not be met by some natural pet foods. To ensure a food meets a pet's minimal nutritional requirements, owners should only buy products that carry at least one of two nutritional adequacy statements from the Association of American Feed Control Officials (AAFCO), which sets guidelines for the production, labeling and distribution of pet food.

It's also important for consumers to distinguish between terms such as natural, organic and holistic, Nelson said. The AAFCO currently has no specific definitions for holistic or organic pet foods.

Pet owners also need to read the ingredients on pet food labels. For example, cats and dogs shouldn't eat onions or garlic. And although flaxseed oil can provide fatty acids for dogs, it doesn't do so for cats. Nelson advised owners not to buy pet foods with these ingredients.

"Most reputable companies have a veterinary nutritionist on hand. These companies also conduct nutritional research and have their own internal quality control in place," she said.

If you buy natural pet foods, monitor your pet's health, she added.

"Assuming the diet you have chosen meets AAFCO minimum standards of nutritional adequacy, and if your pet looks healthy, has good coat quality, and is in good condition [and is regular], the diet is probably adequate for him," Nelson said.

More information

The U.S. Food and Drug Administration explains pet food labels.