To try to gauge the levels of bacteria in these products, researchers took samples from 60 packs of raw meat products, bought from a range of stores within a 200 km radius of their laboratory between March and September 2017.
All the products, made by 10 different manufacturers, originated from Sweden, Norway, Finland, Germany or England.
The products, which were all intended for dogs, contained at least one of: uncooked meat and edible bones and/or organs from cattle, chicken, lamb, turkeys, pigs, ducks, reindeer or salmon.
Some of the products also included vegetables, vegetable fibre, and minerals.
The samples were analysed for bacteria that could potentially pose a health risk to animals and people: Enterobacteriaceae species; Clostridium perfringens , Salmonella and Campylobacter species.
All 60 samples contained Enterobacteriaceae species, which are indicators of faecal contamination and hygiene standards.
Levels varied widely among the different manufacturers, and in some cases, among the different products from the same manufacturer.
But 31 (52 per cent) of the samples contained levels that exceeded the maximum threshold set by European Union (EU) regulations of 5000 bacteria per gram.
Most of the species identified are not known to cause infection, apart from E coli, which was found in about a third of the samples
C perfringens, another marker of faecal contamination and hygiene standards, was found in 18 samples (30 per cent); two of the samples exceeded the maximum limits set by Swedish guidelines.
Salmonella and Campylobacter are zoonotic species of bacteria – capable of passing from animals to people and causing infection. EU regulations don't permit Salmonella in any animal feed.
Salmonella species were found in 4 (7 per cent) of the 60 samples while Campylobacter species were found in three samples from three different manufacturers.
This is a relatively low level, but possibly because Campylobacter species are very sensitive to freezing, say the researchers.
"It is most likely that Campylobacter was present in more samples before freezing, and that those samples in which Campylobacter was isolated contained very high levels of Campylobacter species before the freezing process, as some managed to survive the freezer," they wrote.
The findings prompted researchers to highlight the importance of careful storage, handling, and feeding of raw meat dog food products because of the potential health risks they pose.
They made several recommendations, designed to curb the risk of infection and antibiotic resistance.
Raw meat dog food should be:
• Kept frozen until use, and thawed at 10°C
• Kept separate from other food
• Handled with separate kitchen equipment or with equipment that is washed thoroughly after use.
Good hygiene is essential, they emphasised: bacteria in the juices from raw meat dog food can splash and spread to other foods and surfaces, and dogs can transfer potentially harmful and/or antibiotic resistant bacteria by 'kissing' faces immediately after eating.
Dogs shouldn't be fed raw meat products while being treated with antibiotics as this could increase the risk of antibiotic resistance, said researchers.
"Dogs in families with infants, elderly people or immunocompromised individuals should also not be fed [raw meat products], as these groups are more susceptible to infections," they warned.
British Veterinary Association Junior Vice President Daniella Dos Santos commented: "This research offers further compelling evidence to support vets' concerns about the potential animal and public health risks associated with feeding pets a raw meat-based diet.
"Bacteria such as E coli and salmonella can cause significant gastrointestinal disease in animals. Pets can also shed potentially harmful pathogens present in raw food into their environment, so there is a risk to owners both in handling the food and coming into contact with the animal. Pet owners who choose to feed a raw food diet should be aware of the potential health risks and take full precautions while storing and handling the food.
"BVA would also not recommend making a raw food diet at home without veterinary guidance due to the potential for nutritional deficiencies in homemade diets.
"We would advise any owner wanting to try a raw meat-based diet for their pet to first consult a veterinary surgeon."
