My sister used the Hartz flea and tick medication on her two cats yesterday afternoon (January 23, 2006 around 1 pm). By 8 pm the oldest cat started having tremors and is now in kidney failure at the vet’s office. The youngest cat is now laying in my sisters house going through the same thing. This was at 6:30 this morning. Please do not use this product on a pet. Anyone that reads this should share it with others. I wish I had heard of this sooner.