What We Put on Our Dogs: Rethinking Parasite Prevention in an Interconnected World

What We Put on Our Dogs: Rethinking Parasite Prevention in an Interconnected World

When we talk about environmental health, we often think of pesticides on crops, microplastics in the ocean, or air pollution from industry. But one of the most potent - and quietly overlooked - sources of toxicity may be curled up next to you on the sofa.

Our dogs are more than pets. They’re companions, co-regulators, and for many of us, they are what reconnects us to the natural world. But in our attempts to protect them from parasites, we may be introducing harm- to their bodies, our homes, and the ecosystems we all depend on.

It’s time we started asking better questions.

🐾 Treatment or Prevention?

Let’s begin with language. What most people call “preventative” flea and tick treatments are not actually preventing anything.

These products don’t repel parasites - they require fleas and ticks to bite your dog in order to work. Once the parasite bites, it dies. Why? Because these treatments contain neurotoxins - compounds designed to disrupt the nervous system of the insect. But those same toxins are now circulating in your dog’s bloodstream, organs, and tissues.

So, we must ask:
If these chemicals kill on contact, what are they doing inside your dog’s body over time?

Cancer is now the leading cause of death in older dogs. In the UK, around 1 in 4 dogs will develop cancer, and nearly 50% of dogs over the age of 10 will receive a cancer diagnosis. With numbers like that, we need to examine every element of their environment - including what we put on and in them.

🐝 What Leaves the Dog Doesn’t Stay There

It’s not just about what goes in. It’s about what comes out.

A growing body of research is uncovering the ripple effects of routine parasite treatments - not just for pets, but for people and the planet. Recent studies from the University of Sussex found that common spot-on treatments like fipronil and imidacloprid:

  • Remain active on a dog’s coat for up to 28 days
  • Are transferred to human hands during petting and grooming
  • Enter waterways through bathing, rain runoff, and household surfaces
  • Were detected in songbird nests, and linked to increased chick mortality

Even though this research focused on spot-on treatments, oral medications often contain the same active ingredients. These chemicals don’t simply disappear after digestion - they leave the body through urine, faeces, and the skin - which happens to be the largest detox organ in the dog’s body.

Whether applied topically or taken as a tablet, these pesticides are not inert. They enter ecosystems, both within the home and far beyond.

🐞 One Dose. 25 million Bees.

Let’s put this into context.

Imidacloprid and fipronil are designed to kill invertebrates. A single monthly flea treatment for a large dog contains enough imidacloprid to kill 25 million bees.

These substances don’t just harm parasites - they are lethal to mayfly and dragonfly larvae, essential food sources for birds, fish, and bats. By disrupting one layer of the food chain, we threaten the balance of the whole.

Before imidacloprid was banned for outdoor crop use in 2018, over 4,000 kg was sold annually in the UK for both agriculture and veterinary use. Since the ban, that number has decreased - but more than 2,500 kg is still sold each year for pets alone. This is now one of the primary sources of pesticide pollution in our rivers and homes.

🧼 Organic Food, Toxic Pets?

Many guardians we speak to are incredibly conscious of their impact. They buy organic food, avoid synthetic cleaning products, grow pollinator-friendly gardens, and shop with sustainability in mind.

But when it comes to their dogs, they often don’t realise that those same pesticides banned from their vegetable patch are being applied monthly to their beloved companions.

Your dog plays in your garden, lies on your bedding, cuddles your children, and swims in wild waters. These treatments aren’t just on them - they’re on everything they come into contact with.

This isn’t about shame. It’s about awareness. Once you know, you can choose differently.

🌍 We Are the Ecosystem

At FETCH, we often say that dogs are our gateway species.

When people begin to care for their dogs in a more holistic way, they start asking deeper questions - about health, about balance, and about what we consider “normal” in a culture of routine chemical intervention.

We invite you to ask:

  • What am I actually putting on my dog?
  • What system does this treatment support?
  • What is the cost of convenience?
  • What ripple does this create - at home, in the soil, in the stream?

Because what we put on our dogs, we put on ourselves.
What washes off them flows into our rivers, our gardens, and even the nests of birds.
We are not separate from nature. We are nature.

🌱 What You Can Do

You don’t have to have all the answers.
But you deserve better questions - and support to make choices that align with your values.

That’s why we’ve created:

These aren’t anti-treatment resources - they are pro-awareness.
We believe in thoughtful care. Responsive care.
Relational care.

Further reading:

By Dr. Alexia Mellor & Stacey Renphrey, Co-Founders of Learn FETCH

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