Scientists Found 'Forever Chemicals' in Cats and Dogs — What the Study Really Says

A worrying phrase can travel faster than the evidence behind it. The new study is worth reading—but it needs more context than a viral post can provide.

The phrase ‘forever chemicals’ is almost engineered for alarm. It describes a large family of manufactured substances that can persist for a very long time, and now a new study has found members of that family in samples connected with household cats and dogs. The important question is not whether the headline sounds worrying. It is what the researchers actually detected—and what those measurements can reveal about the environments pets share with us.

Published in Environment International in 2026, the research measured 36 per- and polyfluoroalkyl substances, usually shortened to PFAS, across pet blood serum, food, tap water and faecal samples. Multiple compounds appeared frequently, and the team explored how exposure profiles differed between cats and dogs as well as how the measurements related to selected clinical markers.

Those findings open several lines of inquiry: where exposure may be coming from, whether pets can act as sentinels for a household environment, and which patterns deserve longer study. They also create an easy route to overstatement. To understand the result properly, we need to follow the evidence from detection, through possible exposure routes, to the much harder question of health significance.

Why are they called ‘forever chemicals’?

PFAS are not one chemical but a large and diverse group. The UK Government’s 2026 PFAS Plan describes thousands of substances grouped together by features of their fluorine-based chemistry. Their useful properties include resistance to oil, water, chemicals and extreme conditions, which has led to their use in products ranging from non-stick coatings and textiles to electronics and firefighting foams.

The problem is persistence. The carbon-fluorine bonds found in PFAS are exceptionally strong, so many of the substances degrade very slowly. Some are also mobile in water, while others can accumulate in living organisms and food chains. That does not mean every PFAS behaves identically or carries the same risk; it means regulators are dealing with a complicated family that can travel through food, water, soil, air and manufactured products.

What did the researchers examine?

The Environment International study targeted 36 PFAS. Researchers analysed serum from domestic cats and dogs and paired those results with samples of the animals’ food, household tap water and faeces.

That combination matters because a blood result shows what is circulating inside the animal, while food and water offer clues about possible intake. Faecal measurements can add information about how substances may leave the body. Looking at all four does not produce a perfect map of exposure, but it provides a fuller picture than testing a food packet or water sample alone.

The researchers also compared PFAS measurements with selected biochemical indicators. Those statistical comparisons were exploratory: they can identify patterns worth investigating, but they cannot establish that a PFAS caused a particular biological change.

What did the study find in cats and dogs?

Of the 36 targeted substances, 11 PFAS were detected in more than half of the dog serum samples and 10 in more than half of the cat serum samples. The profiles differed by species. Dogs showed a higher relative abundance of longer-chain PFAS, while cats showed a higher relative abundance of shorter-chain PFAS and a newer group known as perfluoroalkyl ether carboxylic acids, or PFECAs.

The food and water results produced patterns too. Two emerging substances—HFPO-DA and PFMOAA—were prominent in pet-food samples, and PFMOAA was also abundant in tap water. Using modelling, the researchers estimated that food-derived intake was generally higher than tap-water-derived intake for most of the PFAS examined.

‘Generally’ and ‘estimated’ are important qualifications. The modelling describes these samples and assumptions. It does not prove that every pet food contains the same substances, that food is the dominant route in every household or that a particular UK product caused an individual animal’s exposure.

Why might cats and dogs show different patterns?

Cats and dogs differ in physiology, diet, behaviour and the ways their bodies absorb, distribute and excrete chemicals. The study found compound- and species-specific differences when estimated intake was compared with faecal excretion. One notable pattern involved PFMOAA in cats, where estimated dietary intake was higher than faeces-based excretion.

That result may help researchers decide which exposure and elimination mechanisms deserve closer study. It does not yet provide owners with a practical test or treatment decision. Metabolism, other routes of exposure and the timing of samples may all affect what appears in each measurement.

This is one reason the researchers describe cats and dogs as complementary sentinels. Companion animals share parts of the human environment while processing chemicals differently, so their results may reveal different pieces of the wider exposure picture.

Did the PFAS make the animals ill?

The study does not establish that. Its regression analysis linked PFAS exposure with creatinine in dogs and with biochemical indicators related to liver synthetic function and lipid metabolism in cats. A statistical association means two measurements varied together within the data. It does not, by itself, show that one caused the other.

Health indicators can be influenced by age, existing disease, diet, medicines and other environmental exposures. Establishing harm would require research designed to examine dose, duration, biological mechanisms and clinical outcomes, ideally across larger and more varied groups.

Nor can the study diagnose the cat asleep beside you. A population result may identify a research question; it cannot replace an examination, history and appropriate testing by a veterinary professional.

What should UK pet owners do with this information?

Do not make a sudden diet or water change because of this headline. The research does not identify one commercial brand as the cause, and it does not test whether switching a product improves an animal’s health. Abrupt dietary changes can create problems of their own.

If a pet is unwell, speak to a vet about the symptoms and the animal’s actual history. The appropriate question is not ‘Does my pet have the result from this study?’ but ‘What explains the changes I am seeing in this animal?’

For the wider environmental issue, the UK Government says PFAS are already monitored across water, wildlife and other parts of the environment while significant evidence gaps remain. Its PFAS Plan commits to improving understanding of sources, pathways and exposure, including further work relating to animals and ecosystems.

What happens next?

Useful follow-up research would repeat the measurements in larger populations and different locations, track exposure over time and examine whether the biochemical associations persist after other health factors are considered. Researchers also need to understand why cats and dogs handle particular compounds differently.

The study adds an important piece to the PFAS story: pets may help scientists see environmental exposure from two different biological angles. Its value lies in opening better questions—not in supplying a frightening answer before the evidence is ready.

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Sources and update record

Environment International research article

UK Government PFAS Plan

Environment Agency PFAS evidence summary

Last checked: 16 August 2026 · No corrections recorded.