Here's an idea for a story:
1. The Old Sea Dog
You're on the beach and a dog swims to shore, you take it home. How do you discover its story?
2. Pen Dog Danger
You love drawing, especially dogs until the day one of your creations comes to life. You find he's great at causing problems.
3. Night Dog
You find a mysterious model of a dog in Gran's attic. That night you hear a noise up there and go to investigate. It's the dog - he's moving around and there're flashing coloured lights on his body.