03/02/2026
A new peer reviewed study suggests popular flea and tick pills given to millions of dogs and cats may be quietly impacting the environment. Isoxazoline drugs widely prescribed to protect pets are excreted in f***s, urine, and shed hair, creating potential exposure pathways for non target wildlife. The European Medicines Agency has previously warned these compounds could contaminate ecosystems. Common isoxazolines include afoxolaner (NexGard), fluralaner (Bravecto), sarolaner (Simparica), lotilaner (Credelio), and the combination in Simparica Trio, along with products like Bravecto Plus and NexGard Spectra.
Researchers say dung feeding insects such as flies, dung beetles, and some butterflies may be especially vulnerable. These species are essential for waste breakdown, nutrient cycling, soil health, and natural pest control. In a French study, treated dogs and cats still had detectable isoxazoline residues in f***s months later, and modeling suggested routine use could lead to meaningful environmental exposure.
Separate research links other flea and tick chemicals, including imidacloprid and fipronil, to broader wildlife risks, from bees to songbird chicks exposed via contaminated pet fur. The concern is not a single dose, but the potential cumulative ripple effects of routine use across ecosystems.