What’s in YOUR Food?

What I mean of course, is “What’s in your dog’s food?”

When asked this question, most owners read the list of ingredients found on their food’s label. By law, pet food ingredients must be reported in descending order of preponderance by weight at the time of processing. This means that ingredients that are found first in the list are present in greatest abundance in the food.

There are a number of limitations regarding the type of information that a pet food ingredient list provides to consumers; most of these are detailed in my book Dog Food Logic. However, until recently, it was generally presumed that misrepresenting food ingredients, for example listing an ingredient that is not actually present in the food or failing to identify others, was not one of those limitations. Unfortunately, such a presumption may be ill-founded.

Several research studies published in the scientific literature over the past four years have shown that at least some brands of commercial dog foods have ingredient lists that do not always conform to what is actually in the food.

Study 1:  Four brands of dry dog food that are marketed as novel protein source diets containing venison were tested for the presence of other protein sources (1). Of the four products, two listed chicken and one listed rice protein in addition to venison on their label ingredient panel. Results: Of the four foods, three tested positive for the presence of soy protein and one tested positive for the presence of beef protein. In all of these cases, neither beef nor soy products were reported in the product’s ingredient list. (It is interesting and somewhat ironic to note that one of the foods that tested positive for soy protein carried a front label claim stating “No Soy!”). 

Study 2: The same team of researchers tested four retail dry dog foods that carried a “No Soy” label claim and seven therapeutic dry foods marketed to veterinarians for use in diagnosing soy allergies in dogs (2). Results: Soy protein was detected in three of the four retail brands.  Of the seven veterinary-prescribed foods, four were found to contain low levels of soy protein.

Study 3: Eleven limited ingredient diets (LIDs) and one veterinary-prescribed hydrolyzed protein food were tested for the presence of animal origin ingredients not reported on their ingredient label (3). This study used DNA analysis and microscopic analysis of food particles that allowed the distinction between mammal, fish, and bird tissues. Results: Of the 12 products, the species of animal identified by microscopic and DNA analysis matched the food label’s ingredient list in only two. In the remaining 10 products, bone tissue fragments from one or more unreported animal source proteins were present.

Study 4: Most recently, a comprehensive study published in the journal Food Control examined the content of 52 brands of commercial dog and cat food using DNA analysis. Results: Of the 52 products, 31 (60 %) had no labeling violations, meaning that the protein ingredients that were reported in the ingredient list completely matched the sources that were identified via DNA analysis. However, 21 brands (40 %) contained protein sources that were not listed on the ingredient list or in one case, a protein source that could not be identified. In three of these products, the protein source listed on the ingredient panel was entirely absent from the food. Chicken was the most commonly undeclared protein source in the mislabeled foods. This is not surprising because chicken is generally the least expensive source of animal protein in pet foods. Mislabeling was also more frequently observed in canned (wet) pet foods than in dry pet foods. The presence of goat meat (yes, you read that correctly) was found in 9 products. Seven of these identified another animal species source such as chicken or beef on their label and did not include the more generic “meat” term nor (obviously) “goat meat” as an ingredient.

Mystery Meat 2

Is there any goat in that?

Take Away for Dog Folks: The authors of the first three papers wrote that their objectives were to examine LIDs for the presence of undeclared protein ingredients. Their concern was the increased use of these foods by owners and some veterinarians to diagnose food-related allergies in dogs. If you are not familiar with it, the standard diagnostic approach when food allergy is suspected is to feed a food that contains a single and novel (or hydrolyzed) protein source to the dog for 8 to 10 weeks. This is called an elimination diet and its purpose is to prevent exposure to all potential food allergens. If a dog’s signs diminish, the elimination diet trial is considered positive for adverse food reaction (food allergy) and an attempt is made to identify protein sources that the dog can tolerate. The scientists’ concern was that owners were unwittingly using the LIDs as an alternative to the more expensive and supposedly better controlled veterinary-prescribed foods. The expectation was that the therapeutic foods would contain only what their labels claimed, while the retail LIDs would be contaminated with other ingredients. What they found however, was that both retail foods and veterinary-prescribed foods have the potential to be mislabeled. (Oops).

Regardless of results not always showing what one expects, there are several important issues that these studies expose:

  1. Intentional or accidental? The analytical tests used in these studies are able to detect very small quantities of undeclared protein sources. Therefore, a positive result does not necessarily mean that the source was contributing a large proportion of the food’s protein. It only means that an undeclared protein source was present. This might occur accidentally as a result of ingredient cross-contamination during transportation, via airborne particle transfer in the manufacturing plant, or through the use of equipment that was not thoroughly cleaned between production runs. Regardless of intent, these causes are still problems and should be addressed in good manufacturing practice and quality control procedures. Alternatively, the identification of chicken as the most frequently undeclared animal protein source certainly suggests the potential for intentional substitution and mislabeling, seeing that chicken is less expensive than the ingredients that it augmented or replaced. Because these studies did not investigate the quantities of undeclared ingredients or whether or not their presence was intentional, these are questions that still need to be answered. 
  2. Diagnosing/managing allergic dogs: For those who live with dogs suspected of having a food allergy, these results are bad news regardless of knowing quantities or intent. Although the concentration of a food allergen that is needed to trigger an allergic response in dogs is not known, it is expected to be similar to that in people – very low. These studies suggest that feeding a veterinary-prescribed elimination diet may not be a guarantee that the dog is not exposed to a suspected allergen such as soy. In addition, feeding a dog a retail brand LID may not be an effective approach even when food allergens have been identified. For these reasons, some veterinarians and nutritionists recommend feeding a homemade elimination diet for the diagnosis of food allergies in dogs. Once the allergenic protein is identified, extreme care will be needed during food selection.
  3. Trust: Last, but certainly not least, are the issues of food mislabeling, manufacturing integrity and consumer trust. The cases reported in the most recent study, in which listed ingredients were completely absent from some foods and were substituted with other protein ingredients, are in clear violation of AAFCO labeling regulations. The researchers of that study had purchased the sample foods from retail vendors, which indicates that these violations are occurring without detection. What is not known is whether ingredient substitutions, additions, and mislabeling are intentional or accidental or where within the production chain these adulterations are taking place. What does seem clear however, is that consumers cannot always trust the ingredient list to represent only and all ingredients that are present in the food.

What is a dog person to do?? Remember that a substantial proportion of products that were tested in these studies contained all and only those protein ingredients that their labels reported. They were not mislabeled. If you feed commercial dog food, seek out reputable manufacturers. These are the producers who provide ingredient source information, manufacturing details, safety records, and detailed product information to their consumers. Moreover, ask questions, request information, demand transparency and be a critical thinker (and consumer) for your dog so that you have a better chance of knowing what is in YOUR (dog’s) food.

Cited Studies:

  1. Raditic DM, Remillard RL, Tater KC. ELISA testing for common food antigens in four dry dog foods used in dietary elimination trials. Journal of Animal Physiology and Animal Nutrition 2010; 95:90-97.
  2. Willis-Mahn C, Remillard R, Tater K. ELISA testing for soy antigens in dry dog foods used in dietary elimination trials. Journal of the American Animal Hospital Association 2014; 50:383-389.
  3. Ricci R, Granato A, Vascellari M, Boscarato M, Palagiano C, Andrighetto I, Diez M, Mutinelli F. Identificatin of undeclared sources of animal origin in canine dry foods used in dietary elimination trials. Journal of Animal Physiology and Animal Nutrition 2013; 97:32-38.
  4. Okuma TA, Hellberg RS. Identification of meat species in pet foods using a real-time polymerase chain reaction (PCR) assay. Food Control 2015; 50:9-17.

Interested in Learning More about Canine Nutrition? Take a Look at the new Science Dog Courses!

Interested in learning more about how to critically evaluate and select the best food for your dog? Read Linda Case’s best selling book, “Dog Food Logic: Making Smart Decisions for Your Dog in an Age of Too Many Choices“.

26 thoughts on “What’s in YOUR Food?

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  5. Hi, there is an additional paper, addressing the issues discussed above. I guessed it might add a value…
    Pegels N., Gonzalez I., Garcia T., Martin R.: Avian-specific real-time PCR assay for authenticity control in farm animal feeds and pet foods. Food Chemistry 142 (2014) 39-47.
    Moreover, in our small team at the University we plan to conduct combined PCR-ELISA study on dry dog foods.
    We would like to welcome you to exchange thoughts and maybe a stronger co-operation…
    Best regards,
    PS. Dog Food Logic is a major read for all our students, interested in canine nutrition. Congratulations!


    • Hi Robert, Thanks so much. I was able to get a full-text PDF of the paper that you cited via Science Direct. I am very interested to learn more about the work that your research team is doing and would love to exchange ideas. Your email address suggests that you are with a University in Poland, correct? I am actually coming to your country during the first week of December in 2015 to teach a nutrition seminar for dog trainers, veterinarians and interested pet owners. I am not yet certain where the seminar is going to be held as my hosts have not yet provided details. However, if we are within a reasonable distance of you, I would love to arrange to meet for a visit and discussion while I am there. Please feel welcome to email me privately at lcase@autumngoldconsulting.com. Thanks again for the reference and I look forward to reading studies that your group publishes in the future! And, thanks also for your kind words about “Dog Food Logic’ – I am thrilled that your students are reading it! Best wishes, Linda


  6. Pingback: What’s in YOUR Food? | The Science Dog | Our Life + Dogs

  7. I like to think that preparing my animals’ food myself gives me greater control over all ingredients, but I know that I am still trusting my raw supplier that what is labelled “chicken” or “beef” is just that, and not some other poultry or red meat that happened to be cheap this week! I do think, though, that the more layers of supply and processing there are, the more opportunities for substitution and downright adulteration, often without the knowledge of the supplier of the end product. The recent horse meat scandal in the UK, where many supermarket ready meals were found to have a high proportion of horse instead of beef, is a case in point. When an ingredient is sourced in one – or several – countries, processed in another, stored in a third and finally shipped to a factory somewhere else entirely the potential for additional profit through mislabelling is increased at every stage.


    • Hi Frances – I agree. The authors of the most recent paper initiated their study in part as a result of the horse meat scandal in the UK. (Surprisingly, they did not find horse meat to be one of the undeclared ingredients in their study). Definitely agree that increasing the number of processing steps increases risk for adulteration/mislabeling. Thanks for reading – Linda


  8. Wish the details were more available. I’ve often wondered where they were getting all the duck or venison or whatever rare meat was supposedly in trendy (and relatively expensive) foods and how much of it, vs. other protein sources, is actually present.
    Hope it’s ok, I’ve posted links to this with short extracts in a couple of dog forums.
    Seems a lot of people are having problems with food allergies and suspect chicken.
    Wish I understood better whether it was all chicken . . . or just chicken from certain environments. When I lived in Australia and could get chicken frames for next-to-nothing I fed a lot of chicken to a lot of dogs (I ran a boarding kennel) and never had a problem . . . but Australian rules on antibiotics, etc. are different from US rules.
    (Have Dog Food Logic on order).


    • Hi Jen, If you are sharing content from this post, please include the entire link (that is the easiest way to reblog and helps to prevent misunderstandings). You can just copy/paste the link and that will send interested dog folks directly to the site. LPC


  9. I feed my AB female Acana , which does not specifically mention any grain foods , I suspect she has allergy to grains , it is better then other premium foods but I still see too much shedding and reddish skin etc.

    Do you know if the Acana foods which does not mention one grain and inly mention wolf prey and Cartilage is actually grain free ?


    • Hi Julian – If Acana includes grains, you should see this on the ingredient list. (The papers above were looking at animal protein sources, not grains, so I cannot speak to the presence or absence of grains in a food).I am not sure what you meant by the phrases “wolf prey and cartilage”; if you are referring to animal tissue ingredients, they are of course expected to be free of grains. LPC


  10. Another great one Science Dog. This has been one of my biggest concerns as I dove into the world of dog food several years ago. And how to ferret out the truth? This is step one….acknowledging that there’s more to the story than ingredients listed on a label. Thanks again for your hard work in this area.


  11. One treat producer, Zukes, explains that the presence of lecithin is compatible with their claim, “soy free”. They state that soy’s allergens are from soy protein, and lecithin is allergen-free.

    So, is this (“No soy!”) an act of dishonesty or not?


    • Great question, Harry. My opinion would be that they are not being dishonest, since lecithin can come from several sources and it is not a protein but is classified with fats. And they are correct in saying that lecithin should not trigger an allergic response as it does not contain soy protein. I guess technically, they should say “No Soy Protein”, but I think that is splitting hairs a bit. Best, Linda


  12. Do dog food producers simply use what’s convenient or what costs the least? Be interesting to repeat the tests with the same brands, from time to time. I wonder if the results would show a static list of ingredients, or (unreported) changes in the ingredients.


    • Hi Harry, Nice to hear from you. Hope all is well! Regarding convenience versus cost: I originally had a few sentenced in the piece about this but took them out because, well, I know this is a big surprise, but I tend to “write a bit long…”. So in trying to pare down the piece a bit, a few things went into the edited bin. The short answer is that availability (convenience) and cost tend to go hand-in-hand. If a given protein meal is in abundance (as chicken and poultry meals almost always are), they are going to be less expensive. Obviously, the more exotic the protein source, the less that is available, further to transport, etc, so higher cost. And, for many (not all) foods, the ingredients do change over time as market prices of ingredients fluctuate. Best, Linda


  13. It would be helpful to get the list of dog food brands that did not mislabel their ingredients. Otherwise, I’m not sure what to look out for to know how “reputable” a brand is… They’ll probably all claim to be reputable, and try to give their packaging a reputable look.


    • Hi Anna – Of the four papers, only one identified brands. I chose not to report these because the intent of my article is not to denigrate individual brands but rather to raise the issue of food labeling integrity. (You of course can get the papers and find the brands that are identified if you choose). Regarding what to look for – I give a few suggestions in the final paragraph of the essay and a great deal of detailed information in “Dog Food Logic”. Thanks – Linda Case


      • I read it, but it didn’t clarify it for me, because: if the labels can’t always be trusted, what good is the information? They all seem to provide quite many details on the label. I’m also not sure which questions to ask and to whom (the store people? They just want to sell it). Maybe: “Are you sure that venison was not really a chicken?” 😉 Just kidding, but on a more serious note I don’t know how to tell whether a dog food brand is lying to me or not.

        I haven’t read your book. Maybe it would help to do that:-) but currently there are too many other books on my reading list. I want to feed my dogs decent food, but other than that dog food doesn’t have my interest in particular.


        • Anna…I recommend Linda’s book(s). If you’re into the nutrition nitty-gritty, then I suggest Case’s text, “Canine and Feline Nutrition.” It’s not light reading, but invaluable. I’m working through “Dog Food Logic” and find it slanted towards applying scientific thinking to dog food. Make the time!


  14. Well, I would need to read the original studies, but is it possible that insects are contributing to the protein source? Just the presence may not mean anything, but if the amount is larger, it could be an issue. I mean, the spices we use may have a certain amount of insect larvae & such. I guess I’d just like to dig a bit deeper to see what those unlabeled protein sources are and in what proportions. I also would like to see if there’s a quality control/processing issue, or if this is traceable to the suppliers to dog food processors. As a point of comparison, it might be interesting to look at human processed foods as well.

    Those are a couple quick thoughts that popped into my head.

    Liked by 1 person

    • Hi “Tut” – The proteins were specifically identified (this is explained in the essay), either via a DNA analytic method or microscopically. In most cases actual species were identified; in one study just class of species. Thanks for reading – Linda Case


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