In the realm of pet nutrition, the accuracy of pet food labels is a critical concern. It has been discovered that what is listed on pet food labels may not always match the contents of the product. This issue came to light back in the late 1990s when I was an animal rights activist, investigating rumors that euthanized dogs were being used in dog food. Initially, it was believed that heat processing destroyed DNA, making it impossible to test for such content.
However, a new method, the PCR (polymerase chain reaction), which won the Nobel Prize in 1993, provided a fast and accurate way to identify specific genetic material in samples. PCR became instrumental in detecting DNA in processed pet foods, allowing researchers to compare known DNA of various species with samples from pet food products.
Researchers in Taiwan were pioneers in using this technology to test pet food labels. They found that several products claiming to contain only one type of protein actually contained DNA from cattle, pig, goat, and chicken—proteins not listed on the labels. This mislabeling can occur in two ways: either by containing proteins not listed on the label or by lacking proteins that are claimed to be present. While the former is common, the latter is rare.
Studies using PCR and other detection methods have yielded alarming results. A 2011 study revealed that three out of four venison dry dog foods contained soy and one contained beef, neither of which were listed on the labels. In 2014, research found that three of four over-the-counter foods claiming “no soy” actually contained soy, and four of seven veterinary diets intended for diet elimination trials contained soy protein.
Of 52 pet foods and treats tested for various animal species DNA, almost 40% were mislabeled. A canned dog food claiming to contain “deboned beef and beef broth” contained no beef, only pork. Chicken and pork were the most common unlisted species, with six foods not listing chicken on the label but five of them containing it. A popular dog treat supposedly made with bacon and beef contained only chicken, with no beef or bacon.
Out of all 52 samples, 51 contained chicken, regardless of the label.
In 2016, researchers compared different detection methods using foods from several countries, including the US. The findings were startling, with significant disparities between the labeled contents and the detected content of animal by-products. Of fourteen vegetarian and vegan diets tested, mammal DNA was found in half of them. A 2018 analysis found that half of the foods tested were mislabeled, with unexpected added ingredients being more frequently detected than those missing from the label.
Dog food mislabeling is a significant concern, with many products containing unlisted animal ingredients. A study conducted in Italy found that 13 out of 14 brands had at least one mislabeled product, with dry foods being more likely to contain unlabeled species than wet foods.
Twenty-one dog foods with ‘novel’ or ‘limited’ ingredients were analyzed, revealing that all contained unlabeled species such as cow, pig, goat, and bison. In 2021, a study examining new methods for testing mercury in pet foods also analyzed DNA, discovering discrepancies between labeled and actual ingredients. For instance, a food product listing beef, wild boar, goat, and lamb was found to contain chicken, turkey, and fish instead.
Plant ingredients also faced labeling issues. A product’no soy’ was found to contain soy, and another listing field peas and chickpeas contained flax, oats, and rice instead.
New technology, such as Whole-genome sequencing (WGS), has brought the issue to light, revealing that pet food contains a variety of species beyond what is listed. WGS can determine dozens of species of plant or animal in a food product, and a 2023 study showed that commercial pet food has serious and widespread problems.
The study faced challenges, as WGS had not been used on such complex products before. Despite these difficulties, it was found that WGS could not quantify the amount of each ingredient as hoped, and contamination was found in raw samples of tofu and rice.
WGS is a promising technology, but it has also shown that dog foods fail to meet their labels’ claims. Six tested dog foods contained chicken, even though some claimed not to, and wheat was found in all samples, including those declared gluten-free. Most concerningly, two samples tested positive for dog DNA, which should not be present in dog food.
This highlights the need for greater care in the production of pet food by suppliers and manufacturers, as the problems with commercial pet food are global and not limited to American makers. Recalls due to manufacturer and supplier errors are common, indicating a widespread issue.
Our pets sometimes get sick and even die. Inadequate thiamine and excessive vitamin D cause many recalls. One vitamin D recall is ongoing and expanding. Taurine deficiency causes heart disease in certain dog breeds and killed many cats in the 1980s. Foods claimed to be complete and balanced had issues. New standards were published in 2007 but based on old studies. Similar results are found in Europe, Thailand, and Brazil where recalls also happen.
A veterinary diet for cats had a label issue. US companies ship worldwide. Only one study on commercial raw diets found over 60% had unlabeled species. Lamb is common in raw dog foods. As an advisor to AAFCO, I presented research on unlabeled proteins in pet food. Diagnosing allergies is hard. Blood, hair, and skin tests are inaccurate. A strict elimination diet is best. Many companies make diets for allergic pets but DNA analysis shows most contain unlisted proteins.
Five of six foods without chicken on label had chicken. The dog keeps scratching and people don’t know why.
A positive test due to an unlabeled protein could eliminate a diet that might otherwise be ideal. Interestingly, the renderers stayed silent. Rendering is a very secretive industry. Dry pet foods rely heavily on rendered ingredients such as meat and bone meal, poultry meal, lamb meal, etc. Independent renderers accept raw materials from any source. They know how and why so much contamination occurs. Insiders say that, while it is easy to separate streams of materials right from the beginning of the process, renderers simply don’t bother. The philosophy appears to be: “grind it up, spit it out, and slap any old label on it.”
I suggested that the meat industry might want to “clean up its act.” The audience booed! They didn’t want to hear it. They didn’t want to discuss it. But mostly they didn’t want to do anything about it. FDA, state officials, manufacturers and suppliers have yet to take any action. Further studies show the problem is only getting worse.
I’ve worked with these people – regulators, manufacturers, suppliers – for more than twenty years. We generally have very congenial working relationships. But apparently, I poked a very grumpy bear with my remarks!
I’m also a member of the American Academy of Veterinary Nutrition, which has an email bulletin board. I posted about this issue and asked, “What’s going on here?” I got very few responses, but one really surprised me. This expert blamed the problem on “cross-contamination.” For example, she said, in a warehouse there could be a big pile of chicken meal next to a big pile of pork meal. Air currents could blow a little chicken into the pork, or vice versa. PCR is such a very sensitive test. PCR could be detecting the tiniest morsel that drifted from one pile to another! In fact, there is a lower limit of detection for PCR, and it is extremely unlikely that a few flakes of pork meal drifting to the pile of chicken meal would meet that threshold.
Another suggestion made slightly more sense. The cookers, extruders, dryers, and other machinery are supposed to be thoroughly cleaned between runs. That is, a batch of chicken dog food shouldn’t be run after a batch of salmon dog food without thorough cleaning in between. But if the cleaning isn’t done, or isn’t done well, those pesky PCR tests might pick up some residue left behind. The same goes for the trucks and railcars that deliver ingredients. Who wants to spend time and soap and water washing those out?
Makers of “veterinary” diets need extreme care because their formulations are precise. They are generally much better about ingredient purity and cleanliness than OTC foods. But remember, four out of seven veterinary diets still contained detectable levels of contamination.
Now, we needn’t discuss open piles of ingredients sitting in a huge warehouse. We don’t have to consider how those bulk ingredients would be scooped from that pile by a front-end loader. Nor must we imagine how easily the contents of the loader escape as it trundles around the factory.
The pet food industry is fraught with problems that are evident but unlikely to change.
Where are the missing ingredients? It’s not just about ingredients mislabeled or misplaced; it’s about products claiming to contain none of what they list. This silence from within companies is deafening, and naming names can lead to retribution.
We are aware that suppliers sometimes cheat, as evidenced by the 2007 melamine recalls, where companies aimed to increase profits by substituting inferior ingredients. The similarity in appearance between various meat meals makes it challenging to distinguish one from another, even for large, multinational companies.
How discerning is PCR testing? Labs from 1999 already indicated that DNA detection in cooked products is challenging due to the degradation caused by heat. PCR requires intact DNA for species-specific detection, which then undergoes purification and additional processes.
General PCR applications have a sensitivity range of five to 20 mg/kg, with increased accuracy demanding more resources and cost. Most pet food studies are qualitative rather than quantitative, focusing on the presence or absence of DNA.
The importance of accuracy is highlighted in human medicine, where severe allergies can be triggered by as little as 10 parts per million of an allergen. This makes the detection of unlabeled species in pet food a significant concern for potential allergic reactions.
The pet food industry’s disregard for consumers is not just limited to potential allergens but extends to ethical and religious considerations. Many households adhere to kosher, halal, or vegan practices, and the industry’s lack of care for these dietary restrictions is evident in the presence of contaminants like pork in dog food or animal products in vegan pet food.
Another overlooked issue is the risk to young children who may come into contact with pet food, as they are in the stage of putting things in their mouths.
Imagine a child with a severe allergy to a pet food ingredient or even a contaminant. Tragically, a little girl who occasionally ate from the cat’s bowl suffered a fatal reaction to penicillin, which was found in the cat food at 600 times the maximum allowable level for human consumption. This raises the question: How is this acceptable? It isn’t. Such practices are considered adulteration and misbranding, which are violations of the Food, Drug, and Cosmetic Act, a law that applies to both human and animal food. Mislabeling is not only unethical but also illegal, as it fails to accurately reflect the contents of the package.
Adulteration refers to the presence of substances that should not be there, such as plastic, rodent feces, excessive pesticide residues, or antibiotics. Misbranding violates federal and state laws, including the FDA Compliance Guidelines, which require preventive controls for known hazards. The industry’s uncaring attitude has likely contributed to the rise in food allergies, which now affect up to 25% of dogs with allergic skin diseases, a significant increase from the 10% observed in veterinary school.
The cleanliness of equipment is also questionable and may violate HARCP (Hazard Analysis and Risk-based Preventive Controls), the current basis for food safety management. HARCP has replaced the stricter HACCP (Hazard Analysis and Critical Control Points) and covers everything from raw materials to finished products. However, HARCP is criticized as being self-regulatory, allowing producers to create their own safety protocols.
Food allergies are a significant concern for humans, affecting up to 10% of the population, and can be fatal even at 10 parts per million. For dogs, who consume the same food daily, even smaller amounts of allergens can lead to cumulative reactions. A review of evidence up to 2018 concluded that up to 80% of various pet food diets may contain unlabeled species, a concerning statistic that is likely an underestimation. Whole-genome sequencing studies suggest that contamination is common, if not universal, in pet food.
According to these trials, novel-ingredient or single-protein diets are likely to contain unlisted proteins. Even if one bag of food is free from contamination, the next may not be, highlighting the inconsistency and potential risk in pet food quality.
Additionally, many allergic dogs develop new allergies over time. When pet food labels fail to accurately state what’s in the food, both you and your dog are the biggest losers. The issue of pet food quality and purity impacts the entire industry.
It’s time for pet owners to get serious about their dogs’ well-being as pet food makers seem uninterested. I believe there might be small, local companies doing a good job and having our pets’ best interests at heart. But competing at a national level often requires compromises.
Homemade Is Safer! The only reliable solution for a safe, healthy diet, especially an elimination diet, is homemade dog food. If you haven’t made dog food at home before, it may seem daunting. But once you get the hang of it, it goes quite smoothly. (Learn how to make homemade dog food.)
You make the food from fresh ingredients you buy at the store. That’s the only way to know for sure what’s in the food. The same high standards should be applied to any supplements. In most cases, you can skip supplements for at least a few weeks to make the food as pure as possible.
A true allergy elimination protocol lasts for eight to twelve weeks. By then, you’ll be a pro and it’ll be great to watch your dog’s symptoms disappear.
The benefits of a balanced and lovingly prepared homemade diet are not just for food-allergic dogs. When your dog transitions to a homemade diet, it will be happier, less anxious, and more energetic. In fact, it’ll be back to the normal loving dog it was as a puppy!
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