Browse the aisles at your local pet store, and you might notice an increasing number of foods touted as having raw ingredients.

Raw diets have been growing in popularity as some consumers  have become convinced of the purported benefits—from shinier coats and cleaner teeth, to a longer life. Sales of raw frozen and refrigerated pet foods in the U.S. grew by 263 percent from $43.7 million in 2011 to $158.7 million in 2017, according to market research firm GfK.

But raw food diets are controversial, and many veterinarians and public health officials are warning consumers about the potential dangers of these diets.

Some of these products contain raw organ or muscle meats and whole or crushed animal and fish bones. Others are more akin to a raw vegetarian diet, including unpasteurized milk, uncooked eggs, as well as raw fruits, grains, and veggies.

Some vets say these combinations may not be nutritionally balanced. And because the ingredients are uncooked, they may be a source of bacteria and other pathogens that can cause foodborne illness to pets and people.

If you’re thinking about putting your pet on a raw food diet, here’s what you need to know. 

The Risk for Your Pet

Public health agencies such as the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC)—as well as the bulk of veterinarians and professional vet organizations—all warn against feeding pets raw food. 

“These diets could expose animals and humans to dangerous bacteria such as Salmonella, E. coli, and Campylobacter,” says Michael San Filippo, a spokesman for the American Veterinary Medical Association (AVMA).

The FDA is concerned about the public health risks of raw diets, according to a statement on the agency’s website. Scientists from the FDA's Center for Veterinary Medicine (CVM) analyzed in a 2014 study 196 frozen raw cat and dog food samples they purchased online. Fifteen tested positive for Salmonella, and 32 contained Listeria monocytogenes.

In a study published last month in the journal Vet Record, Dutch researchers found that 28 of 35 commercial frozen raw meat-based diets from eight different brands were tainted with antibiotic-resistant E. coli bacteria. Eight samples tested positive for E. coli O157:H7, a particularly nasty strain that, in humans, can cause bloody diarrhea, abdominal pain, and possibly lead to kidney failure and death. (This strain was responsible for a recent food poisoning outbreak in the U.S. and Canada linked to leafy greens.) Samples also tested positive for Listeria and Salmonella.

Raw food manufacturers try to minimize this risk, but it can be challenging.  

Michael Vogel, co-owner of Smallbatch Pets—a raw pet food company that recently recalled two lots of its raw frozen chicken blend for dogs and cats due to potential contamination with Salmonella—says the company is trying to solve the problem of bacterial contamination by sourcing "the highest quality, human grade, USDA-inspected cuts of meats available to us."

Bette Schubert, a co-founder and senior vice president of sales and education at Bravo, another raw pet food manufacturer, says the company follows strict safety protocols, such as sourcing high-quality ingredients, keeping the facilities clean, and treating and testing the products before they go out the door. 

Some raw pet food advocates say the risks of foodborne illness are overblown because people know to be careful handling raw meat. And there's disagreement about how much risk the pathogens pose to pets.

"Dogs and cats are biologically designed to consume raw meat," Vogel says. "Their dentition, saliva, extremely acidic stomach acid, and short digestive tracts are optimized for consuming raw meat that may contain pathogens."

But while it's true that "dogs are a little bit less sensitive to bacteria than people," says Martine Hartogensis, D.V.M., a supervisory veterinary medical officer at the Office of Surveillance and Compliance at the FDA/CVM, "they can still get sick from it.” Symptoms in both cats and dogs include diarrhea, vomiting, fever, and lethargy.

The Risks for You

Even if pets don’t become ill, they can still transmit these bacteria to their owners.

Authors of a 2017 study published in the journal BMC Veterinary Research found that, compared to dogs given commercial diets, those fed raw food are about 23 times more likely to shed Salmonella organisms in their feces. This can pose a risk to you when you’re cleaning up after them, says Lisa M. Freeman, D.V.M., Ph.D., a professor of clinical nutrition at the Cummings School of Veterinary Medicine at Tufts University.

Your pet can also transfer the bacteria to you in other ways, she says, by licking your face after eating, or by scratching you after stepping in their own feces. Petting your dog or cat can expose you to bacteria, too, if some of the raw food or their feces gets stuck on their coat.

And if you don’t follow proper food safety practices while preparing raw food for your pet, says James E. Rogers, Ph.D., director of food safety research and testing at Consumer Reports, you can accidentally infect yourself.

“Since you’re not eating the pet food, you may not think you have to take the same care to wash your hands or the utensils you use,” says Rogers. “But you can easily get sick if you touch your mouth after being in contact with contaminated food, surfaces, or utensils.”

When You Don't Know It's Raw

In addition to frozen or fresh raw meat or meat and vegetable blends, raw foods for pets come in freeze-dried or dehydrated forms. “Most people don’t realize that bacteria can survive the process of freeze-drying,” says Rogers.

Some products may even appear to be conventional dry pet food, says Freeman at Cummings School of Veterinary Medicine, but may have a raw meat coating or may be mixed with freeze-dried raw chunks.

“These foods usually say ‘raw’ somewhere on the label,” says Freeman, “but it's not always obvious.”

Dried or freeze-dried rawhide chews, pig ears, cattle hooves, hearts, tracheas, and bull or steer penises (often called bully or pizzle sticks) can also be contaminated with Salmonella and other bacteria, she says. The FDA in November updated a warning about bone treats after about 90 dogs became ill after eating them between 2010 and 2017. In addition to symptoms such as choking, intestinal obstruction, and cuts and wounds in the mouth, illnesses also included vomiting, diarrhea, and rectal bleeding. About 15 dogs died.

At least nine people in the U.S. and Canada were sickened between 2004 and 2005 with Salmonella after feeding their dogs raw beef and salmon pet treats. And a large Salmonella outbreak in Canada in 1999 was linked to raw pig ears.

Questions About Nutrition

Advocates for raw food diets, especially those who sell them online, claim a range of benefits for pets, including fresher breath, more energy, and better overall health. But, says AVMA’s San Filippo, “there is no scientific evidence to support claims that raw food diets are better for pets than commercial diets.”

In fact, studies have found that raw food diets—both prepackaged and home-prepared—may not offer a healthy balance of nutrients for your pet, especially for growing puppies and kittens.

In a 2011 study published in the British Journal of Nutrition, European researchers found that of 95 homemade raw meals for dogs they analyzed, 60 percent had deficiencies or excesses of 12 important nutrients. A smaller study Freeman published in the Journal of the American Veterinary Medical Association in 2001 looked at three home-prepared and two commercial raw diets, and found them to be lacking in some essential nutrients, such as vitamins A and E, and contained overly high doses of others, such as vitamin D.

Freeman also says that raw meat diets tend to be high in fat, which may have the nice effect of making your pet’s coat glossier, but may also cause mild to severe gastrointestinal issues or increase the risk of obesity. A number of reports have also found that dogs on raw diets can have elevated blood levels of the hormone thyroxine, which can indicate an overactive thyroid.

And diets that contain raw bones may fracture your pet’s teeth as well as puncture the esophagus, stomach, small intestine, or colon.

Some evidence does suggest that raw foods are easier for dogs and cats to digest than cooked.

But Beth Hamper, D.V.M., Ph.D., a veterinarian at the VCA Advanced Veterinary Care Center in Indiana says, “I feel the risks of a raw meat diet outweigh the few benefits, such as higher digestibility and palatability. I discourage owners from feeding their pets these diets.”

Stay Safe When Feeding Your Pet

The FDA says the best safety move is to avoid the raw diet for your pet completely. Conventional dry, semi-moist, and canned pet foods, while not immune to contamination, are less likely to be tainted with pathogens than raw meat-based diets because they’re cooked. And, says Hartogensis at the FDA's Center for Veterinary Medicine, they’re also designed to provide your pet with all the nutrition they need.

However, the FDA also acknowledges that some people prefer to feed their pets raw food. If that’s what you decide, keep the following tips in mind:

Talk to your vet. A survey published March 2017 in the peer-reviewed journal PeerJ found that among 2,171 pet owners, nearly 40 percent reported feeding their pets a diet of raw animal products. Of those, just nine percent had discussed this decision with their veterinarian, and 20 percent had used information they read online to determine what or how much raw animal product to feed their pets.

Because both commercial and homemade raw diets for pets tend to have major nutritional imbalances, ask your vet whether a given raw diet is safe for your pet. If you do decide to make your pet a raw meal from scratch, ensure that the recipe has been formulated by a board-certified veterinary nutritionist, says Freeman, and that you follow it exactly (in her experience, this often doesn’t happen).

Some commercial raw diets are intended only for “intermittent” or “supplemental” feeding, says Freeman. Because these are not nutritionally complete or balanced, they shouldn’t be your pet’s sole source of nutrition.

Freeze the food until you’re ready to serve. Freezing won’t kill any bacteria that may be already present, but it will keep them from multiplying further. Once you’re ready to use or serve raw food, says the FDA, thaw it in your fridge or microwave instead of on your countertop or in your sink.

Once thawed, handle the food with the same care as you would fresh, raw meat. Don’t rinse raw meat, poultry, fish, or seafood in your sink, because any bacteria they contain can spread to other food or surfaces, and store raw food in separate containers from other food.

If you make raw food meals at home, remember that it’s no less likely to be contaminated with bacteria or parasites than a store-bought one, says Freeman.

Clean and disinfect everything that touched the raw food. Wash countertops, the insides of refrigerators and microwaves, kitchen utensils, food bowls, and cutting boards with hot, soapy water to kill any bacteria that may be present. Then use a disinfectant. This can be a commercial product, or you can make your own, the FDA says, by mixing one tablespoon of bleach with four cups of water; for a larger batch, mix a quarter cup of bleach with a gallon of water. Wearing gloves, wipe down the contaminated surfaces with the solution with a clean sponge or rag. A dishwasher can also clean and disinfect.

And don’t forget your hands. Wash vigorously with soap and warm water for at least 20 seconds.

Properly store or dispose of leftovers. If you don’t feed your pet an entire raw meal, cover and refrigerate the food in a sealed container or bag that is properly labeled. Store it separately from your own food. If your pet leaves some leftovers behind in its bowl, toss the rest and sanitize the bowl after every meal.

Take care around your pet. Don’t kiss your pet around its mouth, or let your pet lick your face, especially just after it has eaten raw food. Wash your hands after touching or being licked by your pet.