The Need for Rigorous Feeding Trials and Quality Control in Plant-Based Companion Animals Diets

DOGS

The 2015 JAVMA study, “Assessment of Protein and Amino Acid Concentrations and Labeling Adequacy of Vegetarian Diets Formulated for Dogs and Cats,” found that all seventeen dog food products and two dog/cat products met amino acid requirements for adult canine maintenance based on the lab analysis of one sample (1). However, only eight of these diets—three of which require a veterinary prescription—complied with U.S. labeling regulations. That’s right: less than half of the over-the-counter dog diets had packaging that properly displayed nutritional information as required by law.

Although one can question some of the companies’ quality assurance practices, this study does not provide any data showing that plant-based diets in general or even the specifically studied diets are unsafe for dogs to eat. In fact, the little data collected suggest (but do not confirm) that even the inappropriately labeled dog diets were nutritionally adequate from an amino acid standpoint.

Even though protein and its building blocks tend to get the most focus in discussions on plant-based canine diets, amino acids are just some of the many nutrients required to maintain a dog’s health. Consistently producing a complete and balanced dog food is a complex process that requires proper testing and assurances. For instance, simply adding too much Vitamin D to batches on any given day could result in toxicities and even deaths. Ideally, a formulation has undergone feeding tests to ensure the digestibility and bioavailability of essential nutrients. Then, the company must regularly test products leaving the warehouse to verify consistency.

As I mentioned in my recent magazine article, the vast majority of natural/holistic dog food products, whether meat-based or plant-based, have not undergone formal feeding trials likely due to both the monetary costs and ethical dilemmas associated with animal testing. They also typically do not manufacture their products in their own plants, instead hiring third parties to do so. Therefore, it is not surprising that the three veterinarians who wrote the paper, two of whom are board-certified veterinary nutritionists, suggest that the three prescription diets may be a better choice for consumers who do not wish to feed their dog meat. This viewpoint is supported by a few facts: One of these diets underwent AAFCO feeding trials substantiating its nutritional adequacy for puppies and adult dogs. All three of the diets are produced by companies that are hailed by many veterinary nutritionists for their quality control measures, even more so for their veterinary therapeutic lines. However, none of the three current vet diets are completely free of animal-derived nutrients, and the one (Purina HA Hydrolyzed® Canine Formula) that passed feeding trials for puppies and adults contains trans fat. This type of fat is not well-studied in dogs, but has been found to have many deleterious effects in humans. As discussed below in the cat section, the manufacturer of the other two diets, Royal Canin, does do significant internal product testing for Royal Canin Veterinary Diet® Canine Vegetarian Canned and Dry Foods. Thus, they are likely adequately tested trans-fat free vegetarian options for adult maintenance.

CATS

The data from this study on current commercial plant-based options for cats suggest that these diets should not be considered. Six out of seven plant-based diets, which included products labeled for only cats and dogs/cats, were found to be deficient in essential amino acids for cats based on the lab analysis of one sample each. These results echo the 2004 study I discuss in my previous article that found two vegan cat diets to be deficient in essential nutrients (2) . As such, we need not even discuss label regulations to be concerned with the quality control of these diets.

When it comes to live cats eating plant-based diets, we are even more lacking in data than in dogs. There was a study (also discussed in my previous article) that looked at Vitamin B12 and Taurine in live cats eating a variety of vegan diets (3). However, this study yielded mixed results and Vitamin B12 and Taurine are actually already supplemented from non-animal sources in conventional cat food. A bigger concern is arachidonic acid, which no company has proven can be utilized efficiently from a non-animal source in cats. The closest thing we have currently have to a vegan diet that has been fed and studied in live cats in a controlled setting is Royal Canin Veterinary Diet® Feline Hydrolyzed Protein Adult HP, a hypoallergenic feline diet that utilizes hydrolyzed soy protein as its only protein source. However, this diet contains chicken fat for arachidonic acid, fish oil for EPA/DHA, and some animal-sourced vitamins. It should also be noted that like many of Royal Canin’s veterinary diets, it does not officially carry a label stating it has passed AAFCO feeding tests. Still, Royal Canin does study all its veterinary diets in live animal colonies for extended periods of time.  The diet also carries an S/O index label, which means it is good at preventing both struvite and calcium oxate urolithiasis. The former has anecdotally been an issue with cats eating commercial vegan diets.

Note: The original version of this blog was written for a dog food company I no longer support. Any promotional material has been removed, dog information has been updated, and cat information has been added.

1. Kanakubo, Kayo, Andrea J. Fascetti, and Jennifer A. Larsen. “Assessment of protein and amino acid concentrations and labeling adequacy of commercial vegetarian diets formulated for dogs and cats.” Journal of the American Veterinary Medical Association 247.4 (2015): 385-392.

2. Gray, Christina M., Rance K. Sellon, and Lisa M. Freeman. “Nutritional adequacy of two vegan diets for cats.” Journal of the American Veterinary Medical Association 225.11 (2004): 1670-1675.

3. Wakefield, Lorelei A., Frances S. Shofer, and Kathryn E. Michel. “Evaluation of cats fed vegetarian diets and attitudes of their caregivers.” Journal of the American Veterinary Medical Association 229.1 (2006): 70-73.

2 thoughts on “The Need for Rigorous Feeding Trials and Quality Control in Plant-Based Companion Animals Diets”

  1. Hello, and thank you for this blog! I’m currently feeding my adult dogs a commercially available vegan kibble (Natural Balance), and some of the research of finding mammalian DNA in vegetarian foods and the foods not actually being complete is disturbing. I am unable to find the names of the companies with incomplete (or vice versa, the ones that ARE complete) formulas. I’ve requested the full text from Kanakubo et al. but I wonder if that even names the foods? Do you happen to have this list? Thank you for your time.

    1. Hi Tara,

      Glad you found this useful. The Kanakubo paper does not list specific foods. I contacted one of the authors who told me she did not want to approve or condemn any of the specific companies. This makes sense as only one sample was taken for each food, only amino acid profile was examined, and lab analysis does not directly translate into live animal results (due to factors such as digestibility and bioavailability). All the dog foods were found to be complete in amino acids based on that one sample, but many of the companies are not properly labeling their foods. Natural Balance does not appear to be one of them making labeling errors, but it also does not manufacture food in their own plant or formally test their food in live animals. If you are worried, you can have your vet send plasma samples out to UC Davis to test taurine and amino acids. If s/he uses UC Davis directly, it should be less expensive for you. I plan to write a blog touching on this topic soon.

      Do you have a citation for mammalian DNA in vegetarian foods? I have read about human DNA potentially being in mock meats, but this was not from a peer-reviewed study. If true, I would imagine it would be from cross-contamination in production. There is good evidence about cross-contamination in companion animal foods, which is why over-the-counter limited ingredient diets are not appropriate for food allergy/sensitivity trials (1, 2). Veterinary prescription/therapeutic diets developed for food allergies/sensitives tend to go undergo a much stricter manufacturing protocol, which includes preventing cross-contamination. Please let me know if you have trouble finding the paper and I can send a copy of the study.

      1. Raditic, D. M., Remillard, R. L., & Tater, K. C. (2011). ELISA testing for common food antigens in four dry dog foods used in dietary elimination trials. Journal of animal physiology and animal nutrition, 95(1), 90-97.

      2. Okuma, T. A., & Hellberg, R. S. (2015). Identification of meat species in pet foods using a real-time polymerase chain reaction (PCR) assay. Food Control, 50, 9-17.

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