Thanks for the replies - happy to report our "Billy Dog" was totally fine, thankfully. He either didn't manage to mouth the cane toad, or if he did it must have been extremely brief. No symptoms at all.

All in all, we really just had a rude shock to finally encounter a cane toad in the backyard. If nothing else, it was a wake-up call for DH and I that we ARE living in cane toad country these days!

Cheers, Andie