A recent recall of a raw pet food diets in the US due to contamination with Listeria monocytogenes has sparked some concern about the risks to people (and pets) that might have been exposed to these products.

In some ways, the big concerns raised by the recall are misplaced, not because it’s not an issue, but because a large percentage of raw diets are contaminated with pathogenic microorganisms, but most raw food isn’t tested for them. So, this is not likely a rare scenario, it’s just one that we found out about.

It’s not clear what (small) percentage of commercial raw diets actually are tested and how (since when a company doesn’t really want to find anything, they would tend to use methods that don’t look too hard). In this case, “The issue was discovered during a facility inspection conducted by the U.S. Food and Drug Administration (FDA) and The North Carolina Department of Agriculture (NCDA).” It’s not reported whether they identified issues with the facility and processes that triggered the inspection, or if they just collected samples for testing during a more routine visit.

That’s not to say Listeria in raw pet food isn’t a concern. It certainly is, but this recall has only flagged a small number of contaminated raw pet food products.

If we look at past studies of raw pet food, we know that finding bacteria like Salmonella, Listeria and E. coli (including multidrug-resistant strains) is common. A large FDA study in 2014 found Listeria in 16% (32/196) raw pet food samples, but in no dry pet food diets. So it’s totally unsurprising to find this bacterium (and others) in raw diets. It’s actually surprising to me that they bother to recall these diets at all, since it should be assumed that all raw diets that don’t undergo a pathogen reduction step (like high pressure pasteurization) are contaminated with pathogenic organisms. We expect these to be contaminated, whether they’re bought at the grocery store or a pet store. (That’s why we are supposed to cook raw meat and use good food handling practices for human food as well… since we often don’t do those well, it’s also why people end up barfing a lot).

What are the health risks from these diets contaminated with Listeria?

Risks to people

Listeria is certainly a concern in people, especially those who are elderly or pregnant. It can cause serious foodborne infection and outbreaks. In the US, approximately 1600 people get listeriosis every year, and about 260 of those people die from the infection. That’s not a huge number of infections, but that proportion of serious illness and death means we pay attention to it.

I’ve never seen a human infection with Listeria linked to raw pet food, but it’s certainly plausible that it could occur. The risk is probably pretty low, since infection would require ingestion of the bacterium from raw pet food, but given how poorly we often handle food (human or pet) and the potential for cross-contamination with human food, we can’t dismiss the potential, particularly in household with high-risk individuals.

Risk to pets

Listeria can cause disease in dogs and cats, but it’s quite rare since both species are fairly resistant to infection. The health risk to an average, adult, otherwise healthy dog or cat is going to be really low. Risks are probably highest in older dogs or cats, and in pregnant animals.

What should be done if someone has purchased a recalled diet?

Overall, the risks to people in most households are low. The problem is inadvertent ingestion of Listeria from contaminated hands, contact with the dog’s face after it eats or cross-contamination of human food. Listeria exposure is also a concern through consumption of some human foods (classically deli meat) so we have think about this raw food exposure alongside the broader ecosystem of exposures that we have.

The FDA recommends: “If you find that you have products from Lot 21244, please contact Viva Raw at info@vivarawpets.com for a refund on any remaining product—you should then destroy the food in a way that children, pets, and wildlife cannot access. Do not feed the recalled product to pets or any other animals. FDA recommends humans do not touch the contaminated food product with bare hands. While wearing gloves or using paper towels, place the contaminated food in a sealed plastic bag and throw it in the garbage. Areas that may have come in contact with the contaminated product should be sanitized. Do not sell or donate the recalled products.

For pets

If a dog or cat has eaten a recalled diet but still looks healthy, don’t worry. Testing a healthy pet that has eaten one of these diets is not something I’d recommend.

For people

Talk to your physician if you’re concerned” is always the default answer, but realistically it’s very unlikely anything would be done for a person who is healthy. However, if someone is sick and has had contact with the recalled diet (or any raw diet), they should make sure their healthcare provider knows about the potential exposure to Listeria and other nasty bacteria.

Take home messages:

Feeding raw diets to pets carries inherent risks to pets as well as people.

Risks are greatest to individuals (animal or human) who are immunocompromised, elderly, very young or pregnant, so raw diet feeding in household with those individuals poses extra risks.

Raw diets are best avoided since there’s no evidence they are superior to cooked diets. However, if someone really wants to feed a raw diet anyway, those treated with high pressure pasteurization (HPP) are presumably lower risk, because HPP reduces (though does not necessarily eliminate) pathogenic bacteria in the food.

If a raw diet is fed, basic food handling and hygiene practices are the key, focusing on the food, the food bowl, any areas that the food contacts, and the pet’s feces. More information about raw diets and risk reduction can be found on the Worms & Germs Resources – Pets page, including our recently updated infosheet on raw diets done in collaboration with the Ontario Animal Health Network.