I have used Frontline for flea and ticks for years with no issue. However, after purchasing from PetcareRX, they are scratching as if they were never treated. I'm wondering if their Frontline is bogus? Thankfully, no chemical burns as some pet owners pets have experienced. Also, they call saying they have a question about your order but it's actually a sales pitch to buy their pet membership. No more business from this owner of 6 pets!