Blog Post: Neonics – Why Are We Pre-Treating Our Pets With This Neurotoxin?

In my role as Natural Heritage and Communities Officer for NLOW, I feel it is my heavy-hearted responsibility to pass on information about an environmental issue that people are largely unaware of and yet is super-close to home: the routine use of neonicotinoid-based flea treatments on our pets!

Since I found out myself (only a few weeks ago) I’ve been talking to people in the NLOW project area, and asking “Did you know that Neonics are used in spot-on flea treatments?” – the results of my casual surveys sadly are ‘no’ – it seems the vast majority of folk are unaware of the potential harm these chemicals pose not only to our beloved animals but also to the broader ecosystem and very possibly our own health!

Understanding Neonicotinoids

Neonicotinoids, commonly referred to as “Neonics,” are a class of neuro-active insecticides chemically similar to nicotine. Initially developed in the 1980s, they have become prevalent in both agriculture and veterinary medicine due to their effectiveness against a wide range of pests. To illustrate their potency, Professor Dave Goulson has highlighted that just one teaspoon of certain neonicotinoids, such as thiamethoxam, is sufficient to deliver lethal doses to approximately 1.25 billion honeybees The environmental risks of neonicotinoid pesticides: a review of the evidence post 2013 – PubMed

In the UK, Neonics have been extensively used in agriculture, particularly as seed treatments for crops like oilseed rape and sugar beet. However, mounting evidence of their detrimental effects on pollinators led to increased scrutiny. Notably, in 2013, the European Union imposed restrictions on certain Neonics due to their potential harm to bees. And as it stands, the EU has fully banned the use of neonicotinoids both as seed coatings and in other applications.

But we, as EU leavers, still run the gauntlet of regular lobbying from British Sugar and the National Farmers’ Union (NFU) for ‘emergency exemptions’, and it was by the skin of our teeth that this government didn’t grant the exemption this last January 2025.

And so for a while I can breathe easier, living, as I do, with a colony of wild honey bees in my garden and a neighbouring farmer that grows sugar beet. But it stumps me why…in amongst all  the agricultural decisions around Neonics there doesn’t seem to be many discussions around harms in the home from the same product?!

The Perils of Preventative Treatment

In this country we sign up to the idea that fleas need warded off at every turn. I often think it might go back to the plague times…and fair enough maybe…an atavistic fear deep within us?! But a monthly dose of a neurotoxin on the neck of a retriever – even if there are no signs of louping interlopers? I don’t really understand where that sprang from?

Renowned entomologist Dave Goulson aptly questions our approach: “We wouldn’t treat our children for head lice before they have them, so why are we pre-emptively applying neurotoxins to our pets?” Wouldn’t you like to wait for clear evidence of infestation?

From Soil to Songbirds: Neonics have their impacts

The environmental ramifications of neonic use are profound:

• Soil and Plant Uptake: Neonics are systemic, meaning they’re absorbed by plants into all parts of the plant body and can persist for years in soil, affecting millions of non-target organisms.
• Aquatic Life: Studies are definitive and have detected high levels of Neonics in UK rivers, posing significant risks to aquatic invertebrates.
• Bird Populations: Songbird nests are being contaminated by insecticides applied to pets. “The compounds frequently found in shampoos, spot-on treatments or impregnated collar flea treatments for cats and dogs were identified in fur taken from the nests of blue tits and great tits in the UK”. These pesticides have now been linked to a higher chance of these songbirds’ eggs failing to hatch and chicks dying in the nest.So on one hand we are carefully pouring nuts into our bird-feeders and on the other…unwittingly lining their nests with an egregious toxin. Alarmingly, research indicates that 100% of blue tit and great tit nests sampled contained Neonics in the pet hair linings, with clutch success rates correlating negatively with contamination levels.

And shockingly ‘Flea treatments for companion animals don’t have a thorough environmental risk assessment, unlike for agricultural pesticides,’ says Cannelle Tassin de Montaigu, an ecologist at the University of Sussex, UK, who carried out the research. It was decided that there weren’t enough pets in the UK to bother…I doubt that was true then but try 22 million dogs in the UK now!

Local Concerns: NLOW’s Wildlife Ponds

At New Life on the Old West, we’ve worked hard to create wildlife ponds that provide a haven for aquatic life—newts, dragonflies, frogs, and all the incredible species that depend on clean, chemical-free water. These ponds were carefully designed to support biodiversity, helping to restore what has been lost in our landscape over decades.

However, when dogs, treated with flea products, run into these ponds, they unknowingly introduce powerful neurotoxins into the water. Chemicals that persist in the environment, affecting invertebrates—the very foundation of the pond’s food chain. Without these tiny creatures, everything from fish to amphibians and birds struggles to survive.

Obviously we don’t want to stop dog walkers from enjoying our shared green spaces but if we don’t raise awareness of the unintended consequences, we simply won’t see healthy aquatic life returning to these ponds.

So we’re asking for your help. If you can, consider alternative flea treatments that don’t rely on Neonics and only treat when there’s a problem. Wash your animal’s bedding regularly…that’s where the eggs hide. We bought Neem powder for our Cosmo, it turns him a little green and it’s more of a preventative measure but I urge you, if your dog is treated with Neonics, try to avoid letting them enter wildlife ponds or waterways for a few months afterward. Small actions like these can make a huge difference.

Human Health

Beyond environmental concerns, there’s growing evidence suggesting that pet owners risk contaminating their hands with neurotoxins for at least 28 days after application. This prolonged exposure raises questions about potential impacts on human health, including risks to unborn babies. Goulson postulates that the insecticides could be harmful for human health. “More broadly, the environmental impacts of pet parasiticides need to be subject to proper risk assessments. At present they aren’t, based on a decision made long ago that pesticide use on pets was likely to be trivial in the grand scheme. If they’re on our hands then these neurotoxins will be all over our homes. That doesn’t sound healthy to me.”

For a deeper dive into this topic, consider watching Dave Goulson’s discussion on neonicotinoids, fleas, and sugar beet: Neonicotinoids, fleas and sugar beet

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