Do you brush your dog and leave the hair for birds to build their nests?
Recent research shows:
Flea treatments can be found in the urine and hair of not only treated but also untreated dogs and, worryingly, even in the nests of blue tits. This is probably due to dog hair being used by birds as nesting material.
Even products given orally as tablets result in marked contamination of water that dogs swim in (Diepens at al., 2022)
The research shows that the flea treatments are transferred between dogs, which makes it likely to be spread to family members as well.