 The owner explains that Barko was once the North's greatest champion, but now he's old and stricken with rheumatism.It is then revealed that the other dog team is Soapy Slick's champion racing team (as the owner tells Donald this, Slick and his team pass).Scrooge remembers how Barko helped deliver serum to Nome (a reference to the 1925 serum run to Nome).