I spoke with a vet tech and she said with large dogs it is less of a concern. That "probably" a small dog would not have a problem; but that it is always safer to err on the side of caution and check the blood.
But....here is something creepy.....some rat poisons still contain strychnine. I just found the following link that is really frightening:
Beware - Rat Poison Doesn't Only Kill Rats - It Can Kill Dogs Too!