This post is to answer the question from Erin (in Scotland!) about how themes are chosen for litters so here's a brief explanation.
Theme ideas are submitted to CAST, from raisers, graduates, supportors, etc. The litter is born, seen how many pups, boy/girl ratio and then an appropriate theme is chosen from the list. They have to ensure there is enough names and enough boy/girl names to make sure all the pups fit into the theme. The raisers are notified that they are slated for a pup from the litter and given a list of approved names, you submit your favorite three boy and favorite three girl names and you find out who you get when you pick up the pup and what name was chosen. You can also submit names that fit in theme and they'll decide if it will fit in the theme or not.
I hope that helps a little. There is no telling what theme will next, just have to wait and see after the pups are all born! (No litters that I know of as of yet, probably won't be for a while yet that another litter will be born)