Rainbow, like Val asked, had you sprayed your lawn or garden recently? I dealt with many poisoned dogs and cats when I worked in that field, and if your vet sent him home, he must have been pretty confident that your dog was out of danger.
I'm assuming he took blood, right? A thorough screening can usually tell the doctor what the dog was poisoned with, and that could help you in your search, if this was a deliberate act.
Watch your dog VERY closely. Watch for any odd behavior like head tilting, or if it looks like he's chewing on the air. (Sounds weird, but that's the best way to describe it. And if you SEE it, you'll know exactly what I mean.)
How did the vet treat your dog? Fluids, I assume, and did they force feed him a liquid charcoal looking substance? Any other onjections, like antibiotics, or anything like that?
I'm keeping my fingers crossed for you, and your poor puppers. Keep us updated, won't you?
