My husband purchased Hartz Ultra Guard Pro and put it on two of our cats. One is a smaller (though very sturdy) cat named T, the large cat is named B. Immediately after putting the drops on T, she ran to a ‘safety’ place and kept blinking her eyes oddly. This was unusual but she did not seem to be in any great distress. While I was noticing T’s reaction, B was receiving her drops. B was allowed outside. We went into the other room, and within a few minutes heard some thrashing around, once, then twice. Spider senses tingling we jumped and ran to the other room, to find T frothing at the mouth and spazzing out – eyes dilated, racing heartbeat, uncharacteristically tearing things up. I told my husband to go find B immediately. He promptly grabbed her but she seemed ok, while I started up the sink to bathe T. Both cats were immediately bathed with no long lasting ill effects. After reading the stories on this site I’m heartbroken to see so many loved animals lost because this #$*#$(* is on the market. We consider our kitties to be extremely lucky and will never ever use another Hartz product again.