Barbarian always starts with kitten - bug?

I've been playing with a Barbarian character around 20 times now, and I've always started with a kitten, except for the very first time, when it was a dog named Idefix.

On the Wiki it says that the Barbarian pet should be random, but if so, dogs seem to be *very* unlikely, because it has been an unbroken line of cats for many sessions now. Might this be a bug?