Revealing Adulterated Pet Food

A few years ago, Hemopet discussed studies that demonstrated that certain pet foods did contain or did not contain listed or unlisted ingredients on the packaging. Now, thanks to advances in DNA technology and a driven, dedicated, and determined research team led by Sarrah Dunham-Cheatham, PhD, the world found out how extensive and horrifying pet food adulteration actually is. We knew it was bad, but just didn’t realize the extent of the problem. Seriously, our jaws dropped, and our eyes became wide open. 

The Dunham-Cheatham study is unique for five reasons: 

#1. 127 pet food samples were donated. 92 pet food samples were actually included in the final dataset. We are not certain, but this may be the largest or one of the largest pet food study of this kind. 

#2. The study had three objectives: find out the concentrations of total mercury and methylmercury in commercial dog and cat food; the source of the animal and plant proteins and if they are consistent with the pet food label; and, if mercury and ingredient proportions differ among lot numbers and among packages from the same lot number. 

#3. All funding was crowdsourced and none of it came from the pet food industry or government. 

#4. The research team prevented human bias.

#5. The research team asked the reputable publisher to give open access of the results to the public.

Hemopet admires and applauds the research team of Sarrah Dunham-Cheatham, Kelly Klinger, Margarita Vargas Estrada, Mae Sexauer Gustin for their perseverance, dedication, determination to the health companion pets, and the project.  

We encourage everyone to read their research study titled, “Using a next-generation sequencing approach to DNA metabarcoding for identification of adulteration and potential sources of mercury in commercial cat and dog foods.” 

A note of caution for the average reader. As with most scientific projects, the researchers have to defend and support their research methods. It is easy to get lost in that – no matter what you are reading. Once you get past that, we guarantee you will be shocked. Here’s a nugget: where’s the wild boar? 

Finally, we noticed this study has not received the national press it deserves. So, we ask that you pass it along to other companion pet parents. 

Both studies revealed that ingredients with higher economic value (e.g., fish) are often supplemented with or altogether replaced by ingredients of lower economic value (e.g., chicken). This raises concerns that consumers are paying unfair prices for products that purportedly contain high value ingredients, but actually contain low value ingredients. The prevalence of adulteration in commercial pet foods is also of concern for pets with life-threatening food allergies. Such allergies are becoming more common in pets, with beef, chicken, wheat, and dairy-based ingredients reported as the most common food allergens (Mueller et al., 2016). If a consumer cannot trust that a pet food product is free of these allergens, despite the package label, then pet lives are at risk and trust in the pet food industry is severely eroded.


Dunham-Cheatham, Sarrah M., et al. “Using a next-Generation Sequencing Approach to DNA Metabarcoding for Identification of Adulteration and Potential Sources of Mercury in Commercial Cat and Dog Foods.” Science of The Total Environment, vol. 778, 15 July 2021, doi:10.1016/j.scitotenv.2021.146102,

Mercury in Your Pet Food. Animal Radio, 10 Nov. 2018,

Munson, Jeff. UNR Study Shows Mercury Levels in Pet Food Cause for Concern, Fish-Based Foods Main Culprit. Carson Now, 3 May 2021,

Palumbo, F., Scariolo, F., Vannozzi, A. et al. NGS-based barcoding with mini-COI gene target is useful for pet food market surveys aimed at mislabelling detection. Scientific Reports, vol. 10, 20 Oct. 2020,,

Pearce, Ed. Pet Food: Researchers Finding Unexpected Dangers. KOLO, 12 Oct. 2018,

Ricci, R., et al. “Identification of Undeclared Sources of Animal Origin in Canine Dry Foods Used in Dietary Elimination Trials.” Journal of Animal Physiology and Animal Nutrition, vol. 97, 2 May 2013, pp. 32–38., doi:10.1111/jpn.12045,

Wolterbeek, Mike. “Mercury Levels in Pet Food Cause for Concern, Fish-Based Foods Main Culprit.” Nevada Today, University of Nevada, Reno, 29 Apr. 2021,

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