So..around my second playthrough of Black Plague I began to develop this theory about Wilbur Friske, the former overseer of Shelter, and later the monstrosity you face in the Kennel.
First off, though you do not know of him yet, I actually believe you meet him in Overture...fairly early on in fact. Yes..I believe him to be the man who drags off the man locked behind the door (spider-eater) at which point you are in an old, spider infested basement area. My first thought playing Overture is that it was a giant spider that came through the wall, however a couple pieces of evidence made me alter that notion. Obviously, one piece of evidence is manifested first hand in Black Plague. Wilbur tunnels through walls. You also find a note from Elof Carpenter conveying an experience in which he awoke to find one of the medical staff dead, bitten, and Wilbur fleeing into the darkness. It was also mentioned that Wilbur had possibly been sneaking out into the mines...now the most compelling bit of information..the dead man was missing his tongue.
The next segment of my theory centers on his transformation from human to dog man..or whatever the hell he is. Anyway, as stated in the note, he fled to the Kennel near the onset of the Turngait infection. He is cited as "locking himself up with the dogs for protection". Now for the interesting part...who is to say the infection didn't spread to the dogs? Okay, and why is this relevant? Well, one of the most prominent attributes of Turngait is the whole hive mind aspect. Only, the infected humans became a hive...who is to say the dogs that were infected did not become part of a hive. Indeed, I think his present state is the effect of the virus in conjunction with his surroundings that formed him into this beastly humanoid with dog-like compulsions. As a part of the dogs whom the infection was spread to (in this theory), he began to think as part of the pack.
The only hole I see in my theory is why then would the other dogs be killed? I have synthesized a hypothetical explanation for this as well. Perhaps the dogs are merely carriers, but cannot contract symptoms of Turngait. The virus may drive Wilbur the human to become part of a pack of dogs, but not terminate even the most subtle trace of individuality in a dog. And we all know the anthem of the Hivemind, "there cannot be one, there can only be us all."
Hope you enjoyed reading these musings on such a curious matter.