The well-intentioned (and often expensive) act of feeding your pets raw meat may actually be putting everyone’s health at risk, according to research from veterinary scientists at Utrecht University in the Netherlands.
The team found a troubling prevalence of harmful bacteria and parasites in eight major brands of frozen raw meat-based diet (RMBDs) products for cats and dogs after performing microbiological analysis on 35 samples. To reduce the possibility that storage location impacted the results, the RMBD products were purchased from shops in 14 different areas around Utrecht. The findings are published in the journal Veterinary Record.
Varying species of Escherichia coli bacteria were present in 86 percent of samples, and 80 percent contained a type known to be resistant to several antibiotic drugs commonly given to animals and humans. Moreover, eight products from three different brands contained a strain called E. coli O157:H7, a dangerous pathogen that often causes outbreaks of food-borne illnesses in humans. The bacterium produces a powerful toxin that can cause hemorrhagic colitis (meaning hellacious, bloody diarrhea) and may even lead to kidney failure in children and the elderly.
Across all 35 samples, the total content of all E. coli bacteria, measured in clumps of cells called colony-forming units, failed to meet the hygiene threshold required for a food product to be labeled as "acceptable for human consumption". Fortunately for your furry companions, O157:H7 rarely makes animals sick, their bodies simply become short-term carriers of the bacteria until it is excreted in their poop. And although you are unlikely to eat your pet’s dinner, the authors note in their paper that very low doses of E. coli O157:H7 (perhaps as little as one bacterial colony) can cause disease in humans. This means that pet owners may be at risk of contracting a serious infection indirectly.
“This can be through direct contact with the food; through contact with a contaminated pet, such as sharing the same bed and allowing licking of the face and hands; through contact with household surfaces; or by ingesting cross-contaminated human food,” the paper states. “Cross-contamination may occur after preparing RMBDs or cleaning infected food bowls on the kitchen sink.”
The frozen meals also contained Listeria (43 percent of samples) and Salmonella species (20 percent), two big names in human food poisoning.
While Listeria is often benign in cats and dogs, Salmonella poisoning can cause serious disease with symptoms similar to those experienced by people. Just like E. coli, these microbes can get passed to you simply from handling the products or cleaning up after your pet.
Moving on from bacteria, two types of parasites were identified in the RMBDs: Sarcocystis species (11 percent) and Toxoplasma gondii (6 percent). The former rarely causes noticeable disease in pets and humans, whereas the latter travels into the mammalian brain and has been linked to changes in behavior and even schizophrenia.
If you purchase frozen raw pet food, the low storage temperatures will inactivate most parasites, but some RMBD enthusiasts opt for fresher options. The paper cautions that “this study does show that if raw pet food is purchased fresh and prepared at home without freezing, there is a potential risk of parasitic infections in pet animals, which can result in shedding of oocysts in the environment, thereby leading to potential additional exposure to human beings.”
Despite being a small study that focused on only a handful of RMBD brands, the findings are in line with microbiological studies of raw meat performed in other countries, suggesting most if not all raw pet food harbors hitchhiking pathogens.
“Feeding raw meat to pets has been practised all over the world as shown by the several reports from Australia, the USA, Canada and Europe. This means that this issue is of global importance,” conclude the the authors.
And if you're thinking that the benefits to your pets might outweigh the risk, the authors deliver further bad news: The health claims touted on product packaging or ads are merely marketing, and not based on published research.
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