A recent study found concerning levels of heavy metals in dog food. The findings came from Clean Label Project, a nonprofit that tests consumer products and offers certification to brands that meet their standards. Their testing was conducted by an independent, accredited lab.
If you feed your dog kibble, this matters to you. Here’s what the research shows and what you can actually do about it.
Heavy metals including arsenic, lead, cadmium, and mercury have been found at concerning levels in many popular dry dog foods, based on independent testing by Clean Label Project. Dry kibble tested significantly higher than fresh or frozen alternatives. Understanding what is in your dog’s food and how to check your specific brand is the first step toward making a more informed choice.
Heavy metals including arsenic, lead, cadmium, and mercury have been found at concerning levels in many popular dry dog foods, based on independent testing by organizations like Clean Label Project. Dry kibble tested significantly higher than fresh or frozen alternatives. Understanding what is in your dog’s food and how to check your specific brand is the first step toward making a more informed choice.
What the Studies Found
Clean Label Project tested 79 top-selling dog food products for heavy metals like arsenic, cadmium, mercury, and lead. Within this specific dataset, dry dog food tested higher on average for several heavy metals than fresh or frozen options.
Compared to Clean Label Project’s human food database averages (not federal safety limits), the numbers stood out:
- Arsenic: 5.7 times higher
- Lead: 12.7 times higher
- Cadmium: 3.2 times higher
- Mercury: 2.7 times higher
When comparing dry kibble directly to fresh frozen dog food within their sample, dry food had over 21 times more lead and over 13 times more arsenic.
These are striking numbers, but context matters. These comparisons were made against their internal human food database, not against FDA action levels or established toxic thresholds. Higher than human food does not automatically mean unsafe. The FDA has not issued a recall or advisory based on these findings.
A 2021 peer-reviewed study published in the journal Science of the Total Environment found that 81% of dog foods tested exceeded the researchers’ reference thresholds for mercury and 100% exceeded their reference thresholds for lead, adding to ongoing concerns about heavy metals in pet food.
Why Kibble Specifically
Here’s the thing about kibble. It all comes down to ingredients and processing.
Most dry dog food relies heavily on animal meal, which is made from rendered animal tissues that can include organs like livers, kidneys, and spleens. These organ tissues can accumulate heavy metals over the animal’s lifetime through a process called bioaccumulation. Fish meal is particularly prone to mercury.
Beyond the ingredients, there’s the high-heat processing. Kibble is extruded at extremely high temperatures, which can create other compounds of concern like acrylamide. The Clean Label Project found acrylamide levels 24 times higher in dry food compared to fresh frozen options within their dataset. The health impact of these acrylamide levels in dogs is not yet well defined by long-term studies.
The manufacturing process itself doesn’t create heavy metals, but dehydration concentrates whatever is in the raw ingredients. When you take a product and reduce its moisture to around 10%, everything in it becomes more concentrated per weight. Some of the difference between dry and fresh food testing may reflect this moisture concentration difference rather than a true difference in daily exposure.
That said, heavy metal content ultimately depends on ingredient sourcing and testing, not just whether a food is dry or fresh. Fresh diets can also contain fish, rice, or vegetables grown in soil that may carry contaminants. Format alone doesn’t determine safety.
How to Check Your Dog’s Food
This is where it gets practical. You don’t have to throw up your hands and guess.
First, look for third-party testing. Some manufacturers voluntarily test their products for heavy metals and publish the results. This isn’t common, but it exists. Companies that do this will usually make a big deal about it on their website because they know it sets them apart.
Second, check for AAFCO compliance. The Association of American Feed Control Officials sets nutritional adequacy profiles for pet food in the US, but contamination oversight falls under FDA regulations. Meeting AAFCO standards is the baseline, not the ceiling. It doesn’t guarantee a product is free from contaminants, but it does mean the company is at least meeting minimum nutritional requirements.
Third, contact the manufacturer directly. This is the move most people skip, but it works. Call or email the company and ask specific questions:
- Do you test for heavy metals in your finished product?
- What are your heavy metal limits?
- Can you provide Certificates of Analysis for your products?
If a company can’t answer these questions or gives you the runaround, that’s information. Good companies will have answers ready.
Signs of Heavy Metal Exposure in Dogs
This is worth knowing, though it’s important not to panic. Heavy metal exposure doesn’t typically cause dramatic, immediate symptoms. The concern is long-term accumulation.
Watch for:
- Lethargy or decreased energy
- Digestive issues like vomiting or diarrhea that don’t resolve
- Neurological changes like tremors, weakness, or difficulty walking
- Kidney problems, which are particularly relevant since the kidneys filter these compounds
- Unexplained weight loss or decreased appetite
Many of these symptoms have dozens of other causes. That’s why blood work at your vet is the only way to get a real picture. If you’re concerned, ask your vet about heavy metal testing.
Fresh Food as an Alternative
I’ll be straight with you: fresh food consistently tested lower in heavy metals within the Clean Label Project dataset. But there’s an important caveat. Fresh and frozen food is roughly 70% water, so it naturally tests lower per weight. Dogs also eat 2-3 times more fresh food by volume to get the same calories, which narrows the actual daily exposure gap. The raw multipliers (21x, 13x) don’t tell the whole story.
That said, fresh food does tend to use fewer processed ingredients, and the sourcing is often more transparent. But I’m not here to tell you that you have to switch or that you’re poisoning your dog if you don’t.
Fresh food costs more. It’s less convenient. It spoils faster. Not every dog parent has the budget or the time.
What matters is making an informed choice. If you want to explore fresh food options, there are delivery services, frozen foods at pet stores, and recipes you can make at home. Do the math on what works for your household.
What We Do
We have a dog named Hazel. She’s a 2-year-old Aussie doodle with kidney disease (renal dysplasia), which means her diet is a big deal.
We feed her Just Food For Dogs, specifically their renal formula. We chose it for a few reasons, but one of the big ones was ingredient transparency. We can see exactly what’s in her food. We know where the ingredients come from. That matters to us.
Is it perfect? I don’t know. I can’t promise anyone that any food is completely free of environmental contaminants. But we made the choice that felt right for our situation, and we can explain why we made it.
That’s really the point here. You don’t need to panic. You don’t need to throw out everything you’re feeding and start over. You just need to pay attention, ask questions, and make the best decision you can with the information available.
Your dog is counting on you to figure it out. And now you have a place to start.
Disclosures
This article is for informational purposes only and is not veterinary advice. If you have concerns about your dog’s diet or health, consult your veterinarian.
The Clean Label Project is a nonprofit organization that tests consumer products and offers certification to brands that meet their testing standards. Their data referenced in this article was produced by an independent, accredited laboratory but has not been published in a peer-reviewed journal.
Heavy metal levels referenced in this article are compared to Clean Label Project’s internal database averages, not to FDA regulatory action levels. The FDA has not issued recalls or advisories based on these findings. The presence of heavy metals in food does not necessarily mean the levels are harmful. Actual risk depends on the specific levels, duration of exposure, and your dog’s individual health.
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Which dog food brands have the most heavy metals?
The Clean Label Project’s testing found that dry kibble brands across multiple price points and protein types contained elevated heavy metal levels. Fish-based foods tended to test higher for mercury, while foods with rice or chicken by-product concentrated arsenic. Rather than naming specific brands, which change over time, checking the Clean Label Project’s database directly at cleanlabelproject.org gives you current test results by brand. Brands with the Purity Award certification meet their stricter standards.
Can heavy metals in dog food cause cancer?
Research suggests a possible link. Dogs have a higher rate of certain cancers compared to most mammals, and some veterinary researchers have raised questions about whether long-term heavy metal accumulation from food may be a contributing factor. Lead, arsenic, and cadmium are all known carcinogens in humans. Whether daily exposure through food reaches harmful cumulative doses in dogs over a lifetime is still being studied. The concern is real enough to warrant informed food choices, even if the science is not yet conclusive.
How can I reduce my dog’s exposure to heavy metals in their food?
The most effective steps are rotating protein sources rather than feeding one protein every day, incorporating some fresh or minimally processed food into your dog’s diet, and choosing brands that publish third-party heavy metal testing results. You do not have to switch entirely to fresh food to make a difference. Even replacing 25 to 30% of meals with fresh ingredients has been shown to reduce dietary contaminant exposure. Ask your vet for guidance specific to your dog’s health needs.
Are grain-free dog foods safer from heavy metals?
Not necessarily, and sometimes the opposite is true. Grain-free foods often substitute potatoes, legumes, or other carbohydrate sources for grains, and some of those ingredients can carry their own contaminant profiles. The heavy metal content of any food depends more on the protein and ingredient sourcing than on whether it contains grains. Grain-free foods also carry separate concerns from the FDA regarding a potential link to dilated cardiomyopathy, a heart condition, in certain breeds.
Which Dog Food Brands Have the Most Heavy Metals?
Rather than naming specific brands, which change over time, check cleanlabelproject.org directly for current testing results sorted by brand. Their Purity Award certification identifies brands that meet stricter heavy metal standards. Fish-based foods tend to test higher for mercury, while some chicken and rice formulas concentrate arsenic. Reviewing this database before selecting a food is one of the most practical steps you can take.
Can Heavy Metals in Dog Food Cause Cancer?
Research suggests a possible link. Dogs have a higher rate of certain cancers compared to most mammals, and some veterinary researchers have raised questions about whether long-term heavy metal accumulation from food may be a contributing factor. Lead, arsenic, and cadmium are known carcinogens. Whether daily dietary exposure reaches harmful cumulative doses in dogs over a lifetime is still being studied, but the concern is real enough to warrant informed food choices.
How Can I Reduce My Dog’s Exposure to Heavy Metals in Their Food?
The most effective steps are rotating protein sources rather than feeding one protein every day, incorporating some fresh or minimally processed food into your dog’s diet, and choosing brands that publish third-party heavy metal testing results. You do not have to switch entirely to fresh food. Even replacing 25 to 30% of meals with fresh ingredients has been shown to reduce dietary contaminant exposure. Ask your vet for guidance specific to your dog’s health needs and budget.
Are Grain-Free Dog Foods Safer From Heavy Metals?
Not necessarily, and sometimes the opposite is true. Grain-free foods often substitute legumes or potatoes for grains, and those ingredients carry their own contaminant profiles. The heavy metal content of any food depends more on the protein and ingredient sourcing than on whether it contains grains. Grain-free foods also carry separate concerns from the FDA regarding a potential link to dilated cardiomyopathy in certain breeds.
Tyler Tilton
I do not write surface-level dog advice. When our dog got sick, I learned the hard way that most of what is out there is recycled, watered down, or just wrong. I started The Daily Dog to be the resource I could not find, the one that goes deeper, asks harder questions, and gives you the full picture so you can make real decisions for your dog.
