Here’s a link to an interesting article concerning animals recently treated with flea controlling chemicals. These treatments contain chemicals that have been found to be entering watercourses having harmful effects on fish as well as invertebrates.
Of great concern is the impact to aquatic invertebrates, when you take away the base of your food chain every organism is impacted. That means bird species, bat species, fish and mammals.
The message is clear, read the packaging and keep treated animals out of all water and watercourses for at least 48 hours (this is the figure stated by Frontline UK, other manufacturers may vary and their quoted times should be adhered to.)
Below is a link to a publication by Bug Life on neonicotinoids in water.