I've often wondered how far you could go in modifying a dog. I think it would be funny to replace it's paws with wheels. I had in mind the very low friction wheels you find on boards and skates. As for power, with very small electrical motors available today they could be located in the wheel assemblies themselves, while the batteries could be stowed where a superflous organ (e.g. a kidney) had been removed. Lastly, I think it would be visually amusing to replace its tail with an aerial so you can control it remotely like a toy car. Then it would look a bit like a Dan Dare comic "Dog of the Future". Imagine the fun you could have with it in the park, making it zoom up to people barking like crazy.