A new study published in Environmental Toxicology and Chemistry indicates that common pet flea and tick medications may present an environmental risk to wild insects. The research, conducted by French scientists, suggests that isoxazoline antiparasitic drugs, widely used in dogs and cats, could harm non-target species through fecal excretion.
Isoxazoline antiparasitic drugs are a class of medications used globally by veterinarians for flea and tick control in pets. Introduced in 2013, these oral treatments are effective against fleas and ticks for at least a month. Treated animals excrete the drugs through defecation.
The European Medicines Agency has previously identified a risk of these substances contaminating ecosystems, noting a lack of data on their environmental release. Concerns include the potential environmental contamination and impact of veterinary parasiticides on non-target species. The active chemicals in isoxazoline antiparasitic drugs, designed to eliminate pet parasites, could also affect other insects after excretion by treated pets. Research suggests that pets transfer parasiticides to the environment through feces, urine, or hair shedding. Specifically, dung-feeding insects—such as flies, dung beetles, and certain butterflies, which are crucial for nutrient cycling, soil health, and pest control—may be harmed by consuming the feces of treated dogs and cats.
French researchers conducted a three-month study involving 20 dogs and 20 cats owned by veterinary students, all treated with isoxazoline antiparasitic drugs. Feces samples were collected from these pets to assess the potential exposure of dung-feeding insects to the chemical compounds.
The study focused on isoxazoline elimination via feces in dogs and cats. Researchers identified two of the four active substances from isoxazoline antiparasitic drugs in pet feces beyond the recommended treatment period. The environmental risk assessment concluded that dung-feeding insects could face high exposure to these parasiticides from pet medication, which may lead to significant impacts on environmental lifecycles.