I was reading this article about some flea treatments that can be fatal to cats. The treatments are meant for dogs and contain Permethrin which can cause fatalities in felines. 97% of cats treated with the chemical showed signs of poisoning, with 88% suffering convulsions and 10.5% which died or had to put down. The chemical is found in flea treatments, fly sprays and other pesticides. It is harmless to most mammals including dogs. It is so dangerous for cats that they should not even be allowed near a dog that has been treated.