Sore muscles

Question
I think I may have overworked my dog.  He is a 100lb Rott/German Shepard mix and I walked him for about 2 hours today....he hasn't been getting as much exercise lately, so he has been limping and laying on the ground barely moving.  Besides a massage, what can I do to prevent this from happening again?  I don't want him to turn into a stiff board! HELP!

Answer
You can give him two buffered aspirin to help him and yes a massage is actually a good thing for him. To prevent it in the future don't walk him for so long if he hasn't been exercising. They are just like us in that regard, you need to build him up slowly to walking long distances.
My dog is the same way- at 10 yrs old I am careful with her when we haven't been walking as often as I would like too, which means I have to build myself back up to our long walks again.
So smaller walks more often-increasing time and distance.