I know that this is an old post - But it still may help someone. I live in S. Texas on the Rio Grande River. Our toads here are VERY TOXIC too. If the dog just touches the toad and then licks their nose, they ingest the toxin (the toxin is the toads defense) . I have treated my older dogs 2 or 3 times and saved them. I lost them to other problems 3 or so years ago.
I had found out that if you will immediately wash their tongue off (hold a hose with running water over the tongue and wash it, rub with your hand, over and over, just don't drown the dog). Normally that is all that is needed. If the dog has eaten a piece of the toad, they usually will never survive, unless you make them throw up right away. Even though I was sure my dogs had not eaten any of it I still made them throw up just to be sure.
It's easy to make them throw up - just give them straight Hydrogen Peroxide, slowly 2 T (12 ml) or so at a time. Put it in a syringe and very slowly make the dog swallow all of it a bit at a time. They should vomit up EVERYTHING that is in their stomach within 5 min. If they don't vomit within 5 min, do an additional 12 ml slowly. They will get rid of everything and should be perfectly fine.