Listeria raw pet food recall…with a twist

Friend and fellow hockey aficionado, Scott Weese writes in his Worms & Germs Blog that the recent recall of Stella & Chewy’s products because of Listeria contamination is noteworthy.


Because their food is treated with high pressure pasteurization (HPP). That’s a process that uses high pressure to destroy bacteria. My typical line is that I consider HPP-treated food to be similar to commercial cooked products in terms of risk of contamination and public health concerns. Yet, I add in the disclaimer that actual evidence of effectiveness on pet food seems to be limited. It makes sense that it would work; however, various factors impact the effectiveness of HPP so companies should have specific data that show their process works.

So, the big question here isn’t ‘why were bacteria in the food’? It’s raw, bacteria are common contaminants.

The question is ‘why were live bacteria in the food”? Figuring out how Listeria made it through processing is critically important. Hopefully there’s a real investigation into this.

There are a few main scenarios that I can come up with, and they vary greatly in their concern.

Post-treatment contamination: Careful review of the manufacturing process and testing (culture) of various environmental surfaces would typically be part of in investigation of this area. If this was the problem, things such as physical or procedural changes and more QC testing might be indicated.

Ineffective HPP: There could be two different scenarios.

-One is a breakdown in the process, with equipment problems, human error or some similar issue preventing an effective method from working. This is a problem but would presumably be fixable.

-The other (more concerning) one is that the procedure they use is not actually adequately effective.

Figuring out those is important to reduce the risk and help people make informed decisions about buying raw products.