To minimise health risks for humans and pets, people feeding raw meat-based diets to their dogs should follow good hygiene practices when storing, handling and feeding the raw meat, researchers warn.
"The practice of feeding raw meat-based diets to dogs has increased in popularity in recent years," Ingrid Hansson of the Swedish University of Agricultural Sciences in Uppsala, Sweden told Reuters Health. "There are different opinions about the advantages and disadvantages."
Supporters say the diet is a healthier, more natural alternative to commercial feeds. Critics say there are risks involved, especially regarding the microbiological load in the raw foods.
As reported in the journal Veterinary Record, Hansson and colleagues tested frozen raw dog food samples from 60 packs produced by 10 pet food manufacturers. The packs contained uncooked meat, edible bones or organs and originated from Sweden, Norway, Finland, Germany and the UK.
Many of the samples contained levels of bacteria that exceeded official hygiene limits.
"Exceeding the limit does not mean that the feed is harmful for animals," but it does imply that harm is a possibility, the researchers write in their report.
"Dogs in families with infants, elderly people, or immunocompromised individuals should not be fed these diets, as these groups are more susceptible to infections," Hansson said.
Overall, most of the bacteria in the samples would be harmless for consumers, but some can lead to illness and may be resistant to antibiotics, said Joost Hordijk of Utrecht University in The Netherlands. Hordijk, who wasn't involved with this study, has researched bacteria found in pets' fecal matter, as well as the potential antibacterial resistance of that bacteria.
Hansson's team found Enterobacteriaceae bacteria in all 60 samples. Half of the samples exceeded 5,000 bacteria per gram, the threshold for microbial hygiene under European Union regulations.
Clostridium perfringens bacteria were found in 18 samples, and two samples exceeded the 5,000g maximum permitted by Swedish guidelines.
The researchers also found Salmonella in four samples and Campylobacter in three samples.
"Studies have shown that direct contact with pets plays a major role in human salmonellosis and direct transmission has been reported frequently," Paul Overgaauw of Utrecht University in The Netherlands told Reuters Health by email.
For instance, "vacuum cleaner waste from households with raw meat-based diet-fed dogs has also been shown to be more frequently contaminated with Salmonella species than waste from other households," said Overgaauw, who has researched bacteria and parasites in raw meat-based foods for cats and dogs but wasn't involved in this study.
When feeding a raw meat-based diet to dogs, pet owners should be careful about separating human food from pet food in the kitchen and use different bowls and utensils to prevent the spread of bacteria to other foods and surfaces, Hansson and colleagues advise.
"Another great opportunity for dogs to transfer potential pathogenic and antimicrobial-resistant bacteria to humans is by 'kissing' people in the face immediately after they have eaten," Hansson said.