The Cold Patrol

I just read this article, thought you guys might also find it interesting. One thing about it that bothered me though was this statement: "There's no room at the Sirius base for retired dogs. And the dogs-as much wolf as pet-cannot be adopted. They must be euthanized, an act the patrollers do themselves with a pistol."

Now why can't they be put into a home? Are they completely unsocialized? There are no photographs with the linked article, but in the magazine they show one of the men petting one of the dogs and he seemed quite friendly. Any thoughts as to why they have to be put down?