If you suspect that your pet has been poisoned, licked anti-freeze or eaten a plant, chocolate, artificial sweetener, or other harmful substance, contact your emergency veterinarian immediately.  Don't take a wait and see attitude on this or it could be too late.

Also, please check out The American Society for the Prevention of Cruelty to Animals (ASPCA) for a list of poisonous substances so you can pet-proof your home and yard.