Counting the plastic in a bag of kibble

Doges Editorial · 2026-06-20 · 5 min read

Researchers from the University of Sussex and the University of Exeter tested 38 pet food products and found microplastics in 84 percent of the brands. A large dog eating dry food may ingest more than 2,000 plastic particles per day — and the sources of contamination are still unknown.

Between 162 and 2,314. That's the range of microplastic particles a large dog could be swallowing every single day, depending on whether they eat dry or wet food and which brand you buy. Researchers arrived at that estimate after systematically analysing 38 pet food products sold in the United Kingdom — and finding plastic in nearly all of them.

The study was published on June 17, 2026, in Environmental Toxicology and Chemistry by researchers from the University of Sussex and the University of Exeter, with support from the British Hedgehog Preservation Society. It is one of the first systematic attempts to measure microplastic contamination in commercially available pet food — and what the team found was not dramatic or shocking. It was simply present, in brand after brand, waiting to be counted.

What the researchers did

Lead researcher Emily Thrift, a PhD student at the University of Sussex, selected 38 products across 19 brands — spanning dog food, cat food, and hedgehog food at different price points. The team used established laboratory methods to detect and categorise microplastic particles: fragments smaller than five millimetres, typically the result of larger plastic items breaking down in the environment or entering food during processing or packaging.

Dry food showed higher concentrations of microplastics per gram of food. Wet food, however, because dogs eat significantly larger portions to meet energy needs, led to higher total daily exposure. That distinction matters for anyone trying to weigh their options at the pet food aisle.

We found microplastics in 16 out of the 19 brands we tested, including very well-known ones. Given the huge number of pets in the UK, this represents a major, previously overlooked pathway for plastic to enter terrestrial ecosystems.

— Emily Thrift, lead researcher, University of Sussex

What turned up in the bowl

Microplastics appeared in 84 percent of brands tested and in 27 percent of all individual product samples. Cheaper "value range" products consistently showed higher concentrations than premium-priced alternatives — a gap significant enough to be a meaningful finding, though the researchers were careful to note that the contamination pathway remains unclear. They couldn't pin it on ingredients, packaging, or manufacturing at this stage.

For context: microplastics in human food are not new news. Seafood, bottled water, table salt, and honey have all tested positive in prior studies. The Sussex and Exeter research adds pet food to that list — and in doing so, adds an everyday household product to a picture that was already becoming hard to look away from. Dogs live inside our homes, eat from our hands, and sleep on our floors. Their contamination exposure mirrors ours.

Beyond the dog's gut

The concern does not stop at what the plastic might do inside a dog's body. It also extends to what happens after. Dogs excrete microplastics through their faeces — and with tens of millions of pet dogs across the UK, Europe, and North America, the researchers estimate the ecological pathways into soil and groundwater are substantial.

Microplastics are not just a marine problem. Our pets may be inadvertently spreading plastic pollution through their food and faeces, affecting wildlife and the wider environment.

— Professor Fiona Mathews, University of Sussex

Wild animals that eat pet food — hedgehogs supplemented with kibble left in gardens, foxes, other scavengers — are part of the same chain. Fay Vass of the British Hedgehog Preservation Society, which supported the study, noted that while direct health effects on hedgehogs remain uncertain, the accumulation of chemical toxins on microplastic particles is an established concern in the contamination literature.

What happens inside the dog's own body is a newer and more unsettling question. A 2024 study published in Toxicological Sciences examined testicular tissue from 47 dogs and found microplastics in every single sample — a mean concentration of 122.63 micrograms per gram of tissue. Higher concentrations of PVC in particular correlated with lower sperm counts in the canine samples. The study did not trace those plastics back to pet food specifically, and exposure pathways remain unestablished. But it confirmed that ingested microplastics are reaching deep tissues through biological barriers that were assumed to be protective.

What it means for your dog's food

The study was conducted on products sold in the UK, and the brands are not named in the published paper. Whether comparable results would hold across North American or European markets remains to be studied. But given that microplastic contamination appears linked to processing and packaging rather than anything unique to British supply chains, there's little reason to expect UK pet food to be unusually contaminated compared to equivalents elsewhere.

The practical read on the data is modest and honest: premium products showed less contamination than value-range products. Wet food leads to more daily particle exposure despite lower per-gram concentration. And the sources of contamination — whether the ingredients themselves, the packaging, or the production line — remain uncertain enough that no specific brand can yet be selected or avoided based on this data alone.

Our results are a reminder that our pets are exposed to the same chemical pollutants as ourselves. Cleaning up the food chain is a crucial target for the future.

— Professor Tamara Galloway, University of Exeter

What we don't know yet

This study did not measure whether the microplastics found in pet food caused any harm to the animals that consumed them — that would require a different study design, one that has not yet been completed in this population. Research in marine animals and some mammalian models suggests microplastics can carry chemical contaminants and may affect gut barrier function, but translating those findings to dogs eating commercially prepared food is a step the current evidence doesn't support yet.

The honest read on this research is that it establishes something previously unmeasured, not something to panic about. Awareness is not the same as certainty, and certainty about harm has not arrived. But the next time you open a bag of kibble or a tin of wet food, you know a little more than you did a week ago about what's in it — and that's roughly what science is for.