This has all stemmed from the fact that Sparky won't play with him. He's Amy's dog and would much rather follow her around the house or snuggle up on the bed with her than play fetch with Thomas.
So Thomas has decided he wants his own 'forever friend' dog. There are certain stipulations though. It can't grow very big because it has to sit on his knee and sleep in his bed. It's got to be a girl. It has to love him more than anybody else in the family and it has to be called Nina, Fleur or Misty.
The dog he really wants is a sausage dog, but I'm not too keen on them. I find them strange looking dogs with their elongated backs and stumpy little legs.