For most of us, treating our dogs and cats for fleas and ticks is a routine part of responsible pet ownership. However, there is a growing body of evidence to show that the chemicals in these treatments—specifically the spot flea treatments which use insecticides—are filtering into our waterways and causing damage to our precious river ecosystems. 

In Wiltshire, the health of our waterways is vital, as our county is defined by three major river catchments: the Bristol Avon, the Hampshire Avon, and the Thames.

Each of these systems plays an important role in the landscape, but they share a common sensitivity. Many of our rivers in wiltshire are globally rare chalk streams, protecting these catchments is essential to preserving the delicate ecosystems that live within our local waters.

How do flea treatments do harm?

You might wonder how a small dose of medicine on the back of a dog's neck ends up in a river miles away. Unfortunately, it is simpler than you’d think. When a treated pet goes for a swim in a local stream or river, the insecticide washes directly into the water. This is why we always encourage dog owners to, as much as possible keep their dogs on a lead and out of our waterways. Even more worryingly if your pet does stay out of the water, bathing them at home also washes these chemicals down the drain. Most people assume wastewater treatment plants filter out toxins. Unfortunately, these facilities are not currently designed to remove the insecticides in modern flea treatment , meaning they pass through the system and are discharged directly into our waterways. Rain can also wash residues from a treated pet's fur—or even from surfaces they’ve brushed against outside—into surface water drains which feed directly into rivers.

A Silent Killer of Aquatic Life

The chemicals used in many common flea treatments are incredibly potent. Even a microscopic amount can be lethal to aquatic invertebrates like mayflies, dragonflies, and freshwater shrimp. When these insects are affected, the entire ecosystem feels the shockwave. Invertebrates are the foundation of the river's food chain. Without them, fish lose their primary food source, which in turn reduces the food available for birds that live on the riverbank like kingfishers and herons as well as mammals like otters.

A healthy river relies on a delicate balance. When invertebrate populations collapse, it affects everything from algae growth to riverbed plants, leading to an unhealthy, unoxygenated stagnant river.

How You Can Help?

First and foremost the best way to help keep our rivers and waterways healthy is by keeping your dog out of rivers and ponds. Keeping your dog on a short lead when out in nature is the best way to ensure that your four legged friend stays by yours side and not in our waterways. 

The goal isn’t to stop treating your pet, but to move away from the blanket use of harsh chemicals that spot treatments are formulated from. By changing how we manage parasites, we can protect our local wildlife.

Regular grooming is the most effective chemical-free method. Using a fine-toothed flea comb frequently allows you to catch adult fleas and remove eggs or larvae before an infestation starts. When bathing your pet, opt for natural, herbal shampoos containing ingredients like neem oil, lavender, rosemary, or cedarwood. These have natural repellent properties that deter pests without poisoning the water. Look for flea collars that use natural essential oils (such as eucalyptus) rather than synthetic insecticides. These provide a barrier of protection that is much safer for the environment.

Flea treatments are also available in pill form which is less likely to make their way into the watercourse. Do ask your vets for alternative to the spot treatments. 

Our rivers are precious. By making a small change to our pet care routine, we can ensure that our love for our pets doesn’t come at the cost of our local wildlife.