In recent years, the veterinary profession has faced a growing challenge: how to balance effective parasite control in companion animals with the need to protect environmental health. 

Parasiticides - essential tools in preventing and treating infestations of fleas, ticks, and worms - have long been a cornerstone of small animal medicine. However, increasing evidence suggests that their widespread and routine use may be contributing to environmental degradation, particularly in aquatic ecosystems. As pet ownership rises globally and the demand for parasite prevention grows, veterinary professionals are being called upon to adopt more sustainable, risk-based approaches to prescribing these treatments.

 

The environmental impact of parasiticides

Parasiticides are designed to be toxic to invertebrates, which makes them highly effective against parasites. Unfortunately, this same property poses a threat to non-target species. Compounds such as Fipronil and Imidacloprid, commonly used in spot-on treatments and collars, have been detected in household wastewater and surface runoff. These chemicals can enter aquatic systems, where even trace concentrations have been shown to harm aquatic insects, crustaceans, and other invertebrates that play vital roles in ecosystem functioning.

Moreover, oral parasiticides are not exempt from scrutiny. Emerging concerns suggest that these products may contribute to environmental contamination through hair shedding and faecal waste. The cumulative impact of these substances can disrupt nutrient cycling, reduce biodiversity, and impair ecosystem services such as water purification and disease regulation - services that indirectly support human health.

 

A shift toward risk-based prescribing

To address these concerns, veterinary practices are moving away from blanket parasite treatment protocols. Instead, a risk-based, individualised approach is gaining traction - one that considers the unique lifestyle, exposure risks, and environmental context of each pet. This paradigm shift is exemplified by initiatives like CVS Group’s Lifestyle Parasite Risk Assessment, which empowers clinicians to make informed prescribing decisions based on a comprehensive evaluation of risk factors.

Understanding the limitations of a single consultation, CVS's clinical leadership team have consolidated the key factors into a simple to use flowchart, that can be completed by the client while waiting or alongside a clinician during their appointment. Not only does this make decision-making quick and simple, but talking through their pet's assessment helps clients buy-in to the need for, or lack of, particular products.

This approach aligns with the principles of One Health, which recognises the interconnectedness of animal, human, and environmental health. By tailoring parasite control strategies to individual pets, veterinary professionals can reduce unnecessary chemical use, improve owner compliance, and safeguard ecological integrity.

 

Key factors in sustainable parasite control

Achieving sustainable parasite control requires a holistic understanding of the factors that influence parasite risk. These include:

1. Pet-specific considerations. Age, health status, and behaviour are critical. Pets that hunt, scavenge, or consume raw food are at higher risk of parasitic infections, while healthy indoor pets may need less frequent treatment.

2. Environmental exposure. Pets with access to outdoor environments, especially those that swim or roam in areas with high parasite prevalence, face increased exposure. 

3. Household composition. The presence of vulnerable individuals - such as children, elderly people, or immunocompromised adults - can influence treatment decisions due to the zoonotic potential of some parasites.

4. Travel history. Pets that travel internationally may encounter parasites not commonly found in their home environment. This necessitates a flexible and responsive treatment strategy.

5. Owner compliance. Understanding the owner’s ability and willingness to administer treatments is essential. A tailored plan that considers preferred administration methods (e.g., tablets vs. spot-ons) can improve adherence and outcomes.

 

Tools and training for veterinary teams

To support this shift, veterinary organisations are investing in tools and training. CVS Group, for example, has developed a Lifestyle Parasite Risk Assessment tool and accompanying training course. This programme equips veterinary professionals with the knowledge and confidence to assess parasite risk, communicate effectively with clients, and prescribe responsibly.

Key topics covered in the training include:

·        Environmental impacts of parasiticides

·        Best practices from BSAVA and BVA

·        Parasite lifecycle education

·        Zoonotic risk management

·        Practical application in consultations

·        Communication strategies to enhance client understanding

By integrating this tool into everyday practice, veterinary teams can foster more meaningful conversations with clients, build trust, and promote sustainable care.

 

Benefits of a sustainable approach

The advantages of risk-based parasite control are multifaceted:

·        Tailored Treatment: Pets receive the right spectrum, frequency, and method of parasite control based on their individual needs.

·        Improved Compliance: Owners are more likely to follow treatment plans when they understand the rationale behind them.

·        Reduced Chemical Use: Targeted prescribing minimises environmental contamination and supports biodiversity.

·        Enhanced Clinical Outcomes: Early detection and prevention strategies help identify high-risk cases and intervene appropriately.

 

Looking ahead: research and responsibility

While the move toward sustainable parasite control is promising, it is not without challenges. Knowledge gaps remain regarding the long-term environmental effects of various parasiticides, and further research is needed to guide best practices. Nonetheless, veterinary professionals have a responsibility to act cautiously and ethically, using the tools and evidence available to make balanced decisions.

The future of parasite control lies in collaboration, education, and innovation. By embracing a risk-based, individualised approach, veterinary practices can continue to protect animal and human health - while also preserving the planet for generations to come.