WildFish publishes new report on the emerging threat of veterinary medicines to UK rivers

A new report from conservation organization WildFish is drawing attention to a growing but often overlooked environmental threat: veterinary medicines washing into rivers and waterways across the United Kingdom.

The report highlights how common pet treatments — particularly flea and tick medications — are contributing to chemical contamination in freshwater ecosystems. While most pet owners are unaware of the issue, scientists warn that these medications can be highly toxic to aquatic insects and freshwater invertebrates that form the foundation of river food webs.

Invisible Pollution in Freshwater Ecosystems

Freshwater habitats in the UK are already under significant environmental stress from:

• Pollution

• Climate change

• Habitat loss

• Water over-abstraction

According to the report, veterinary pharmaceuticals represent a new type of chemical pressure that is largely absent from public policy discussions but may have long-term ecological consequences for wild fish populations and aquatic biodiversity.

When pets swim or play in rivers, topical parasiticides used for flea and tick control can wash off their fur and enter the water system. Even small concentrations of these compounds may persist in sediments and aquatic environments, where they can harm sensitive invertebrate species.

Regulatory Gaps and Environmental Monitoring Concerns

The WildFish report argues that current regulatory systems are not adequately addressing the environmental risks associated with companion animal medications.

Key concerns include:

• Limited environmental monitoring of pharmaceutical residues in surface waters

• Weak environmental risk assessment requirements for over-the-counter pet treatments

• Regulatory frameworks that may prioritize therapeutic benefits over ecological risks

The report suggests that veterinary medicine regulation, pesticide regulation, and environmental protection laws often operate in silos, creating gaps in environmental protection.

What the Report Is Calling For

WildFish is urging government policymakers to strengthen environmental protections through several measures, including:

• Expanding environmental risk assessments for commonly used companion animal parasiticides

• Establishing national monitoring programs for veterinary drug residues in rivers and streams

• Increasing transparency around regulatory environmental data

• Implementing ongoing reassessment of veterinary products as new environmental evidence emerges

• Closing regulatory gaps between veterinary pharmaceuticals and environmental law

Implications for Veterinary Professionals

For veterinarians, this report highlights the growing intersection between clinical practice and environmental stewardship.

While flea and tick control remains essential for animal and public health, the findings reinforce the importance of:

• Responsible prescribing practices

• Client education about proper application and disposal of topical treatments

• Considering environmental risk alongside therapeutic efficacy when selecting parasiticides

The report ultimately emphasizes the need for balanced approaches that protect both animal health and aquatic ecosystems.

As environmental pressures on freshwater habitats continue to increase, conservation groups warn that addressing pharmaceutical pollution will be essential for protecting fish populations and maintaining ecosystem stability across the UK.