Boris: Let me tell you something Balto. A dog can not make this journey alone, but maybe a wolf can.
Steele: Go ahead wolf-dog! You'll never get home! I'll make sure of that!
Rosie: I'm sure Jenna would have you on our team.
Rosie's Father: Rosie! He might bite you, honey. He's part wolf.
Rosie: Oh, now you hurt his feelings!
Answer: He has an arrogant, power-hungry personality. As the situation with the medicine gets worse, he doesn't want to lose admiration from the humans and other dogs.