Chewy sales Seresto Flea Collars even though they know they have 87,000 EPA complaints, 2340 dead dogs cats, over 1,000 human injuries. That's only at the EPA. More than all other pesticides for pets combined. Think of the oness not reported. Read the reviews on Chewy, PetCO, PetSmart, Amazon, others. There are 100s on chewys alone. I reported the swaying, head bobbing, drooling, anxiousness, hallucinations to their customer service, corporate office. My 4 yr. old GSD now has a brain tumor.