After reading the thread about antifreeze, another thing to watch out for are chemicals used for garden snails and other garden pests.  My sister's boxer, who is notorious for eating things you would never think of (match light charcoal), was being dog sat her friends house where they had snail poison sprinkled on the ground.  Apparently it tastes sweet to attract the snails, but she ate it and had to go to the emergency room because of severe tremors.  I think she'll be ok, but the vet bill was at least $1,200.  Some dogs will eat just about anything.