It may sound a little cheeky, but the Doggy Pedometer is a great tool for monitoring your dog's well-being. Create a profile with your dog's type and feeding schedule, then attach the lightweight pedometer to its collar.
When you come back from work, you'll be able to see whether he's gotten the exercise he needs, shown as both a step count, and "frolicking index" built from his personalized profile. It's a great way to track your dog's lifestyle over time, and get an early warning of any problems he might be having
The Doggy Pedometer features: