Mary Allen
Feeding your dog raw meat is a health hazard. This is the conclusion of a study by the University of Zurich on the subject. It is all the more important to take hygiene measures into account.
Dog and cat owners who feed their animal’s raw meat usually do so because they consider this type of feeding to be the most species-appropriate. By not giving their four-legged friends industrially produced food as food, but what their ancestors ate in the wild: raw meat and innards and bones of prey (see box).
However, the method known by the acronym BARF (biologically appropriate raw feeding) is being questioned more and more critically. Various scientific studies have shown that raw feeding has potential risks. This also applies to products that are available in Switzerland. A study by the University of Zurich at the Institute for Food Safety and Hygiene of the Vetsuisse Faculty in 2019 showed that 29 of 51 samples of raw feed available on the Swiss market from eight different suppliers were contaminated with multi-resistant intestinal bacteria (read more about this here). For Roger Stephan, who led the study, it was therefore clear: “Barf is a risk factor.”
Dangerous Bacteria
After the study at the time was primarily about resistant bacteria, which themselves do not directly cause illness, Stephan and his team investigated the question of whether and to what extent commercially available raw feed is also contaminated with pathogenic bacteria. They focused on Shiga toxin-producing Escherichia coli or Stec for short. These bacteria are found in the gastrointestinal tract of many wild animals and can contaminate meat during slaughter, gutting, and cutting.
In order to find out whether and to what extent Stec is also present in BARF products, the scientists at the University of Zurich examined 59 samples of raw feedstuffs commercially available from ten suppliers in Switzerland, including meat from 14 animal species – from beef to chicken, horses and reindeer, moose to perch.
The results of the study were recently published: Stec was isolated from a total of 41 percent of the samples. “Among them, we also found variants that are highly pathogenic, i.e. can lead to severe disease progression in humans,” adds Stephan. What is special about this group of pathogens is that the minimum infection dose required to become ill is very low. “This means that a so-called smear infection is usually enough to become ill. For example, when dealing with the food or the dishes.” In addition, animals that are fed contaminated raw feed excrete the pathogens with their feces. This is another possible source of infection.
Human Health at Risk
And a Stec infection is not something to be trifled with, as Stephan emphasizes. It can lead to severe gastrointestinal diseases and life-threatening kidney failure in humans. “Stec causes an estimated 2.8 million acute illnesses and almost 4,000 cases of kidney failure worldwide every year,” the study reads. Stephan also points to two documented outbreaks of Stec where raw feeding is suspected to be the source: in 2017, five people in England contracted it, one of whom died of kidney failure. In 2020 there were five cases of illness in Canada, which even led to a large-scale recall of the respective BARF product.
Hygiene when handling raw feeding
Other studies have also shown that BARF can be a risk factor. A research team from the University of Utrecht in the Netherlands examined 35 raw feed samples from eight different suppliers. In more than half, specifically in 19 products, the researchers found listeria (Listeria monocytogenes), which can cause infections in humans. Seven products contained salmonella, which can cause notifiable diarrheal diseases. The parasite Toxoplasma gondii was also detected in two products. This pathogen is feared not least by pregnant women because in rare cases it can lead to eye inflammation and brain damage in the unborn child.
Hygiene Measures are Important
The Zurich researchers conclude that the high incidence of Stec bacteria in raw pet food poses a significant health risk for people who handle raw pet food in the kitchen and for people who have close contact with animals that are fed raw. “In my view, it is important that potential risks and, above all, the necessary hygiene when handling such feed and also barred animals are pointed out,” says Stephan.
The appeal seems to have already been put into practice. In its November 2020 position paper on the subject of “BARF”, the Swiss Association for Small Animal Medicine (SVK) recommends specific hygiene measures when handling BARF products (see fold-out box). Since the SVK offers further training for veterinarians in “nutrition for dogs and cats”, this knowledge ultimately also reaches the dog and cat owners who seek advice in practice. But even owners who feed their animals on their own according to the principles of BARF are advised of the necessary hygiene by most online shops when purchasing the raw feed.