Scientists at the University of Sussex discovered that dogs given flea treatment products containing fipronil or imidacloprid released pesticide levels exceeding safe environmental thresholds, even 28 days after treatment.
These chemicals, commonly used to combat fleas and ticks, pose a significant threat to aquatic life and birds that feed on contaminated organisms.
Advice to dog owners
Lead researcher Rosemary Perkins said, “If your dog swims regularly, you shouldn’t be treating it with spot-on.”
She noted that previous advice to keep animals out of water for 48 hours was untested and unsupported by scientific evidence.
The study involved immersing 49 treated dogs in water-filled tubs at various intervals after treatment.
Risk of pollution
Results showed that a single large dog could pollute a small pond beyond safe limits, with repeated swimming compounding the issue in larger water bodies.
Perkins recommends limiting the use of spot-on treatments to essential cases and avoiding water access for at least a month after treatment. Although oral alternatives exist, their environmental impact remains uncertain due to the presence of chemical residues in faeces.
