The trend to feed dogs ‘natural’ raw meat-based dog food poses a potential threat to human health, researchers from Sweden have warned today after finding* that these products often contain high levels of bacteria. They have urged pet owners to practise especially good hygiene when feeding this type of food to their dogs, and to avoid it altogether when dogs are in households with babies, the elderly or people with low immunity – or if the dogs themselves are taking antimicrobials, because of the risk of resistant strains developing and spreading.
The research team explained in the BMJ-published journal Vet Record that raw meat-based diets (RMBD) – in which uncooked offal does not undergo any form of heat treatment before chilling or freezing – have become more popular, often viewed as ‘healthier and more natural’ for dogs than other commercial foods. But they pointed out that bacteria present in RMBD could pose a risk of infection to humans during handling and storage of the feed, the dog’s feed bowls, possible contamination of kitchen equipment, and also the dog’s tongue, and faeces. And, although RMBD proponents have argued that the microbiological load is no threat to dogs because their gastrointestinal (GI) tract is adapted to raw meat, research has found that pathogenic bacteria isolated from RMBD are excreted in faeces of dogs with GI symptoms to a greater extent than in faeces from clinically healthy dogs.
The researchers took samples from 60 packs of raw meat products, bought from a range of stores within a 200km radius of their laboratory between March and September 2017, to quantify the level of Enterobacteriaceae and Clostridium perfringens, markers for faecal contamination and hygienic quality; to document the presence of two species of zoonotic bacteria, Salmonella and thermotolerant Campylobacter; and to evaluate the presence and amount of bacteria relative to EU and Swedish feed safety standards.
They reported that:
- Bacteria belonging to family Enterobacteriaceae were in all 60 samples; in 31 (52%) of these, levels exceeded EU regulations for microbial hygiene.
- 18 (30%) samples exceeded the detection limit for C. perfringens.
- Salmonella species were found in four (7%) of the 60 samples.
- Thermotolerant Campylobacter species was isolated from three samples.
They said their results “show that it is highly important to handle RMBD carefully and to maintain good hygiene, due to the potential risks these feeds pose to human and animal health. The RMBD should be kept frozen until used, thawing should take place at a maximum of 10°C and the thawed product should be separated from human food and handled with separate kitchen equipment, or with the equipment properly washed after use. Bacteria in the raw juices from RMBD can splash and spread to other foods and surfaces.
“A 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.”
They added: “In view of the resistance problem, dogs should not be fed RMBD while they are being treated with antimicrobials, as this could increase the risk of resistant strains being selected and multiplying. Dogs in families with infants, elderly people or immunocompromised individuals should also not be fed RMBD, as these groups are more susceptible to infections.”
* Hellgren J, Hästö LA, Wikström C, et al. Occurrence of Salmonella, Campylobacter, Clostridium and Enterobacteriaceae in raw meat-based diets for dogs. Veterinary Record (2019) doi: 10.1136/vr.105199.