I will tell you for £20 an hour , the easy answer is shit happens, we can only guess and TRY to interpret what goes on in the dogs mind.....
whot goes on in a terriers mind now that would be some reading
had one the same mate a good while ago now was spot on then one day was having a walk out with another lad and his mutt and his dog went off after a sheep closley followed by mine, you can never be 100% with terriers they have a nasty habbit of proving you wrong when you least expect it.
lethal stuff slug pellets mate, antifreeze is another one, as is rat poison, just have to be extra carefull and read the label before using anything where your dogs are going to be. hope the dogs pull through.
find your local hunt go to a meet or down to the kennels and have a word with them, abit of free work for them will gain you experience and get you some contacts
the lady who spotted him was on the news here saying the lad told her he had been kidnapped when he spoke to her out of the window so dont think its a custody thing