The native people do not keep their dogs in their homes they tie them outside or just let them roam...when the dog population gets too large they start shooting them. I'm sure that some of the ones get shot at found that man south of them.
That, if nothing else explains why the OSPCA might put this in their too hard basket. They could get an unending supply of dogs to try and look after . And trying just enables it to go on IMO. It must be a nightmare working for the OSPCA or shelters in Canada.