I have been asked to cross post this link on behalf of Jackie at Rain Rescue - I don't know anything else about the missing DDB unfortunately.
How very sad for poor Archie - I hope he pulls through and learns to start trusting people in order that he can be socialised, trained a little and eventually rehomed - the poor poor baby:
http://www.rainrescue.co.uk/dogue-de-bordeauxs.htm
Thank you for looking