I sincerely hope it's all an elaborate joke. Think of the animal cruelty complaints!
I lost a pet recently so I would find it very painful emotionally to even consider going head-to-head TF2-style with a dog like that, even if it
is only in a cartoony-looking game world. Heck, I wasn't even willing to play as Heavy for a while after being mugged on the street in May just because of the trauma of being punched to the ground by a stranger (Heavy's fists and all that).
It's one thing to see burly cartoon men blowing each other up. But to see burly cartoon men blowing innocent dogs up ... I wouldn't be surprised to wake up and find TF2 (Valve too, even) dead, smashed overnight by animal rights complaints (which I would not consider totally unjustified).