Fleas and ticks can be a nightmare for any pet owner to deal with. But the proper treatment of these foreign parasites can come with more dangers to the environment than we knew, scientists have recently discovered.
French researchers tested the feces of cats and dogs for certain antibiotics known as isoxazolines. They continue to find some of the drugs in their pets’ feces even after their treatment ends. They also concluded that important, fecal-loving bugs may be exposed to dangerous levels of these compounds through insecticide-treated pets.
“These findings emphasize the need for more research on environmental pollution and the impact of veterinary parasiticides on non-target species,” the researchers wrote in their paper, published Wednesday in Environmental Toxicology and Chemistry.
A simple but potentially dangerous option
Isoxazolines are a new class of antiparasite drugs, and the first drug of its kind was approved in 2013.
These medications quickly became a popular choice among veterinarians and pet owners for several reasons. They can treat both ticks and fleas, are usually available as an easy-to-take pill, and provide a long-lasting effect (at least a month) that can prevent further infestations. One of the new drugs approved on the market, Bravecto Quantum, can work for up to a year, although it must be taken as an injection.
As impressive as isoxazoline is, some experts and health agencies are concerned about the impact it can have on non-target insects and other arthropods, as these drugs enter the environment through pet feces, urine, and even hair. The European Medicines Agency (EMA) has recently called for a review of the potential environmental impact of flea and tick medicines. They realize that the increase in domestic animals and the increase in the use of these drugs may raise environmental risks.
The researchers employed 20 dogs and cats that were student animals for their studies. The pets were given one of four commonly used isoxazoline drugs as recommended for three months (fluralaner, (es)afoxolaner, lotilaner, and sarolaner), and the researchers periodically checked their feces for traces of each.
All the drugs had an average half-life ranging from 15 to 25 days, they found, although it varied by brand and specific drug. And two drugs (fluralaner and lotilaner) can still be found in pet feces after the recommended treatment period has expired.
The researchers also simulated the potential risk of these drugs left in livestock to the dung-eating insects in the wild, based on their results. They concluded that in many cases, there may be a real risk of overexposure to these drugs, especially fluralaner and lotilaner.
Need to learn more
These findings do not prove that isoxazolines cause harm to insects everywhere. But they highlight the urgent need for more research to determine how harmful they can be to innocent insects in parks and other places where pets regularly do their business.
“Our preliminary evaluation suggests that animal ectoparasiticides can be harmful to the environment and supports the conclusions from the scientific opinion of the EMA,” the researchers wrote.
A better understanding of these risks can help us and reduce them. In countries and regions where garbage is routinely burned, for example, it may be beneficial to recommend that pet owners always dispose of their pet’s feces in the garbage during flea or tick treatments, the researchers suggested as a possible idea.
