What is the antidote for frog poisoning?

To the best of my knowledge, there is no antidote. "Frog poisoning" is actually a syndrome associated with dogs trying to chew on frogs and toads; there isn't a single chemical that causes this (or it hasn't been identified). Generally a dog that is showing acute respiratory and gastrointestinal symptoms after chewing on a frog or toad is treated symptomatically until it passes.