Parasites, prescribing, and our planet: rethinking parasiticides in the One Health era

We all know how unpleasant - and potentially serious - a flea infestation can be to pets and their owners alike. However, while year-round parasite prevention and blanket prescription use has been the norm for many years, research has begun to shed light on the negative impact that these medicines can have on the environment, leading many veterinary professionals to reconsider how and when they are used.  

The One Health perspective 

One Health recognises the connection of animal health, human health, and environmental health; nowhere is this more pertinent than in our approach to parasite control. Effective parasite management supports animal welfare, prevents zoonotic disease transmission, and reassures owners. But the overuse or inappropriate use of parasiticides - particularly in the absence of robust risk assessments - can also pose a threat to biodiversity and aquatic life. 

Some of the active ingredients in parasiticides are incredibly potent. That is their strength, but also their Achilles’ heel. When residues from spot-on treatments wash off during bathing, swimming, routine grooming, or the washing of pet bedding, they can enter water systems. Studies have detected fipronil and imidacloprid, both commonly used veterinary parasiticides, in UK rivers at levels that raise concern.

This raises a fundamental question: are we, with the best of intentions, inadvertently contributing to environmental harm through the medicines we prescribe to protect pets?

At a crossroad 

As veterinary professionals, we pride ourselves on our ability to adapt, to learn, and to lead. The issues surrounding parasiticides exemplify the complexity of modern veterinary decision-making. They challenge us to think holistically, to weigh risks and benefits across species and systems, and to communicate clearly with clients who trust us to make the right call for their pets - and increasingly, for their values.

At BVA, we have been calling for more research into parasiticides and their impact on the world and have been encouraging vet teams to consider taking a risk-based, targeted approach to prescribing and using parasiticides, weighing up the risk to pet and owner, and making a decision based on all circumstances.   

We know some practices are already making changes: moving away from default year-round treatment, building parasite risk assessments into consults, and having open conversations with clients. But we also appreciate many vets feel caught between a rock and a hard place: do less, and risk disease, or do nothing, and risk environmental harm.