I bought the flea and tick collar for my 5 month old kitten in 2009 and it burned the fur off the back of her neck in a matter of days. She had scabs for weeks and it took a while for her fur to grow back. Fast forward 9 years: she STILL gets hotspots on her neck from where the collar was. Reading through these stories, I can’t help but feel like her behavior issues are somehow related as well. NEVER USE THESE PRODUCTS.