Feeding your pet raw meat or putting them on a raw food diet could be dangerous for both of you.

Raw food diets for dogs and cats are becoming increasingly popular, but a recent look at dozens of commercially available products found high levels of bacteria. Not only can these microbes make pets sick, they can also make people sick, both from handling the food and from contact with pet waste, including the waste of healthy pets that have eaten contaminated food but didn't get sick from it.

For many people, Salmonella infections are merely uncomfortable. For the elderly, pregnant women, young children and people with weakened immune systems, they can be much more serious.

Researchers from the University of Zurich analyzed 51 raw pet foods made from meat that came from Germany or Switzerland and recently published their results. The findings are troubling enough that the study's lead author, Magdalena NĂ¼esch-Inderbinen, advises pet owners who buy these products to be extra thorough in washing their hands after handling the food or its packaging, and to be aware of the increased risk of disease in their pets. The study was done in Europe, but pet owners who feed raw diets anywhere should take its findings seriously.

Examining only food intended for dogs, the researchers first tested it for Enterobacteria, and found, on average, about eight times the maximum amount allowed by the European Union. Fully 37 of the 51 products contained more than the allowable limit.

Enterobacteria are often used as an indicator of possible dangerous contamination of food. It is easier to test for them than it is to test for individual dangerous bacteria. While most are harmless, several types are not, such as species of Salmonella. Food that has a high Enterobacteria count is likelier to harbor disease-causing bacteria than food with a low count.

In properly cooked food, all Enterobacteria are killed by heating; but bacteria live on in raw food.

Further testing discovered Salmonella in two of the products. Other studies have found it at higher frequency in raw food pet foods from Canada and the United States.

For many people, Salmonella infections are merely uncomfortable. For the elderly, pregnant women, young children and people with weakened immune systems, they can be much more serious, even life-threatening. The bacteria can be spread by unwashed hands, but there are also other ways for them to infect people. After all, what infant or toddler can resist the opportunity to taste their pet's dinner?

Additionally, antibiotic-resistant bacteria were reported in 63 percent of the products.

Taken together, the findings were enough to prompt Lisa Freeman, a veterinary nutritionist at the Cummings School of Veterinary Medicine at Tufts University who was not involved in the study, to offer pet owners some simple advice: “I strongly recommend against feeding raw meat diets for the health of the pet, the owner, and the greater community.”

For more details, see the article in Royal Society Open Science.