Years ago, I saw a guide dog save its owner from a nasty and perhaps fatal accident.
On a slam door train via Nunhead, the train stopped at a signal, and the owner opened the door and was about to step out. Saved by the furious barking of the dog.
I saw what was happening and shouted out STOP DANGER, but doubt if this warning would have been in time.
One failing of guide dogs is that they are trained not to lead the owner into water, but the dog cant judge the depth of the water. A large but shallow flood is very perplexing to the poor dog. A sighted person would wade through and accept wet feet.
Guide CATS have been trialed with mixed results, more funding is needed.
https://newsthump.com/2015/04/01/rnib-launches-guide-cats-for-the-blind-scheme/ Guide cat trials.