by Marion Nestle
May 8 2012

The latest pet food Salmonella recall

A reader writes:

Here’s what I don’t understand.

Everyone who is scared of raw says they want their dog’s food to be cooked, to kill salmonella.

But here is kibble, which by definition is cooked to the point of losing most of its original nutrients, but STILL has salmonella.

I don’t see how this is possible.  If it’s cooked enough to be “kibbled,” how can it possibly still have salmonella? It just seems like the worst of all possible worlds.

This question refers to the recent recall of dry dog food manufactured by Diamond Pet Foods.

As the CDC explains, Michigan public health officials found Salmonella in an unopened bag of a Diamond kibble product during routine testing.  This particular Salmonella strain had been found to infect at least 14 people.

CDC investigators connected the dots between the illnesses and dog food through interviews:

Seven of 10 (70%) ill persons interviewed reported contact with a dog in the week before becoming ill.

Of 5 ill persons who could recall the type of dog food with which they had contact, 4 (80%) identified dry dog food produced by Diamond Pet Foods that may have been produced at a single facility in South Carolina.

In my book, Pet Food Politics: The Chihuahua in the Coal Mine, I tell the story of the massive pet food recalls of 2007 due to contamination with the industrial chemical, melamine.  And in Feed Your Pet Right, my co-authored book about the pet food industry, I explain how pet foods are manufactured and why they are so subject to contamination and recall.

Canned pet foods are sterile.  Dry kibble is not.  It may be sterile at the point of extrusion, but it is a perfect growth medium for bacteria.  It is nutritionally complete.  Although some nutrients are lost during processing, the product formulas compensate for such losses.  That is why dogs can survive on “complete and balanced” dry foods.

If the factory is contaminated with Salmonella, the bacteria can fall into the production lines and get packaged into the kibble bags.

Dogs are relatively resistant to Salmonella and usually do not show signs of illness from eating contaminated kibble.

But humans who handle the food or the dog can acquire the bacteria and get sick.

This makes dry dog food a potentially hazardous product, one best kept away from people with weak immune systems such as young children and the elderly.

People like feeding dry food to pets because it is convenient and cheap.

My point in Pet Food Politics was that pet food is an indicator of problems in food safety regulation.  If pet foods are not forced to be produced under strict food safety measures, humans and the human food supply are also at risk.


  • Gloria

    What I find ironic is that so many people are switching to a raw diet because of this recall.

    Personally, I’m not concerned about salmonella in dog food, but I do have concerns about the general safety of pet food and consolidation within the industry.

  • Pjkobulnicky

    We just switched over to making our own dog food. Turns out it is clearly cheaper than the medium priced kibble. It does take about 45 minutes every three weeks (for a 20 lb dog.) But, we cook it to kill all bacteria and freeze portions as soon as they are cool enough to transfer to containers. Dog likes it and his teeth are cleaner than with kibble.

  • Emma

    Pjkobulnicky, what recipe(s) do you use? I have a couple in the Pitcairn book (which is called something like “Natural Pet Health”) but I have some concerns because he advocates adding garlic to the food, which my vet says is potentially dangerous. I’ve thought about going this route myself, but I want to be sure I’m feeding my dogs well, and because I’ve only ever done the prepared pet food thing, I’m not confident about nutrition and dietary balance and all that.

  • Interesting, but can you please clarify how you think the Salmonella made it from within the factory to the inside of the packaging, and what measures processors can take to prevent this from happening? From your description it sounds surprising that it’s not an even more frequent occurrence.

  • Marion

    @Pjkobulnicky and Emma: I can’t resist pointing out that my book, Feed Your Pet Right, discusses the issues you raise and also provides generic recipes for making your own “complete and balanced” pet foods. These recipes, by the way, are easy to produce and allow considerable variety in ingredients. Enjoy!

  • BB

    Either the raw dog food components contained Salmonella and survived b/c it was not cooked to lethality or it was cooked to lethality and exposed to Salmonella post-lethality which means there are insanitary conditions in the post-lethality environment of the plant.

  • Pjkobulnicky

    As Marion says (sorry but missed your book) it is easy and variable. We do some animal or fish protein based on price and/or availability, some whole grain, some cooked dried beans and bean broth, some veggies and some source of calcium (dried milk, eggs with shells, fish bones, etc) . Grind everything except the grains together, make sure it is soupy, add the raw grains and cook until the grains are done. We do add some garlic salt and some other common spices, probably so it smells good to us. Turns our kind’a meatloaf’ie. I don’t accept the garlic prohibition since it is a recommended additive to a dog’s food when for other health reasons the dog won’t eat. One other thing is that we freeze bits from our own dinners, like the skin and carcass pickings from a roast chicken, and then add that to the mix during the batch prep.

  • Marian, a slight correction. Kibble is too dry to be a good growth medium for Salmonella. But Salmonella certainly can – and, obviously, does – survive on the kibble if it becomes recontaminated after extrusion. My guess is that the production plant had a serious and chronic environmental contamination; otherwise, the contamination would not have been of this magnitude or duration.

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  • Michelle selby

    My dog passed away yesterday. About two weeks ago I gave her a new dog food made by a national brand. The next early morning she was vomiting. The vet thought it was just from switching foods and medicated her to stop the vomiting. Within a couple days her stomache turned black. She was diagnosed with “TEN” A toxic disease that eventually killed my poor baby. She went through two weeks of developing serious jaundice, pancreatitus, a heart murmer and the most disgusting- her entire layer of skin on her chest and belly died and fell off. She fought hard but her little body just couldn’t survive. This all started on 9/10/12 when she ate this new bag of food. I believe it was contaminated. I have contacted the store where I bought it and the manufacturer to remove it. I hope this doesn’t ever happen to another pet, it was a horrible experience.

  • Leslie

    Yay! I’m really happy and relieved to find a trustworthy source for pet food recipes!

    I’m a new-ish dog & cat owner and quickly found myself neck deep in the crazy end of the internet while researching pet foods (both commercial prepared foods and recipes for homemade). There is a lot of unsubstantiated and contradictory “fact” floating around out there! Also, I find the high-pressure sales tactics of pet food companies stalking shoppers at the larger pet stores to be so obnoxious and misinformed that I refuse to ever shop at those major chains again.

    I can’t wait to get this book so I can try the recipes!

    Bless you, Marion!

  • Christine Tapia

    What is your recipe for the dog food? I’d like to start making my own.

  • Marion

    @Christine Tapia: Mal Nesheim and I published a generic, easily adaptable, recipe for dog and cat food in our book, “Feed Your Pet Right.” Maybe your local library has a copy? Enjoy!

  • In cases such as this it’s more likely the kibble is contaminated after extrusion, as you quite rightly point out the cooking process should kill off such bacteria.

    Poor quality control is rife in the pet food industry as it’s not governed as much as human consumption food.

    It’s an interesting point that the salmonella in the pet food is hazardous to the consumers who handle it – everything’s a risk these days!!