hartz flea and tick on myspace

I was reading a myspace bulletin and came across something shocking about how hartz flea and tick caused a dog to foam at mouth and vomit, WOW i thought i was the only one until now.  About a couple weeks ago I went to walmart and got the hartz flea and tick treatment for my dog rusty hes a malti poo and about 12 to 15 pounds, i know for sure i got the right dosage for him.  So we came home gave him a bath and put the treatment on, everything was fine.  I went to my bedroom and was watching tv and when i came out a couple hours later my dog rusty had the hallway covered in vomit and was foaming from the mouth constantly.  I would wipe his mouth off and it would foam as fast as i could wipe it off.  So my first instinct told me to put him in the tub and wash him off and call the vet.  Thank god my vet lives a block away,  she told me that she has also heard of this happening to alot of pets and she told me to give him a low miligram dose of benadryl.  I gave him the benadryl and he slowly started getting better.  the whole night he was ancy and restless but thank God he is still alive,  I couldnt imagine what could of happened if i wasnt home and he was left in the condition he was in.  So that is my story and Rusty is fine now but has anything been done about this and is there anything we can do about it?