Once you start peering at fruits for organic labels and checking food labels for high-fructose corn syrup, it gets a lot harder to just throw a bag of Whiskas in your grocery cart without thinking about it. Just what’s in that bag of food you pour into a bowl each morning?

Feed Your Pet Right: The Authoritative Guide to Feeding Your Dog and Cat, by Marion Nestle (What to Eat) and Malden Nesheim, peers into the pet food industry and advises the ethical animal owner. Nestle and Nesheim are in the middle of a book-reading tour (which includes a stop at the incomparable Omnivore Books in San Francisco on Saturday), but Nestle was able to take the time to answer some questions for CHOW by email.

Domestication has changed the diet of dogs and cats from meat and bones to processed slurries. What ingredients in pet food would surprise pet owners?

We doubt most pet owners realize that virtually all pet foods are made from byproducts of human food production. These are awful to think about—guts, organs, etc.—but really quite nutritious, and cats and dogs like them.

What ingredients do you feel shouldn’t be there?

All pet foods must meet the same nutritional standards. They differ by quality of ingredients. But even ingredients that sound like real foods are mostly parts we humans don’t eat. Again, pets don’t care. But owners do!

Do you have an opinion on whether wet or dry food is better for pets?

If obesity is a problem, wet foods are better because they have fewer calories.

Are there any brands you particularly like on the market?

I don’t recommend specific brands on principle. I had a fondness for Pet Promise because the company sourced ingredients so carefully, but it was bought out by Purina, which dropped it this year.

How does premium pet food differ from what you find at grocery stores?

Premium is a marketing term with no agreed-upon meaning. The manufacture of many brands is contracted out, and as we learned during the 2007 recalls, many brands are made at the same factory using similar ingredients.

Can you turn a cat into a vegetarian? Should you?

Companies make vegetarian foods for pets, but it’s much easier to meet their needs when you feed them mixed diets.

One diet growing in popularity is the BARF diet: bones and raw food. What’s your thinking on it?

Raw is one way to feed a pet and one with particularly passionate advocates. We think it’s not the only way that can work well.

Do you recommend a recipe for those who’d like to make their own pet food?

We have generic recipes in our book that meet complete nutritional needs. These can be adapted for animals of different ages and sizes and to owners’ feeding preferences.

Or make CHOW.com’s recipe for Marvelous Mutt Meatballs.

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