Another running with dog question

A lab puppy that likes to run?  Color me shocked!

A dog will stop when it's tired.  Sounds like you've got a good friend! 

I agree with the concern over the hips, but you really can't stop a 5 month old puppy
when it wants to run ... can you?

I've got an 8 month old golden that seems to never stop moving ... until she stops. She'll get tired and just lay down. And that's it. If we're a few miles from home, I'm screwed

**Edited to add that I am NOT a vet** 

I do some field training and agility training with German Shorthaired Pointers.  I never do any endurance training/running with them until they are a year old.  They still have open growth plates that can be easily injured resulting in growth arrest.  However, I am all for letting them be puppies.  Obedience training, swimming, and playing is not an issue.  Let them tire themselves out.  A tired puppy is a good puppy.  I just don't do endurance runs with them.  My 2 cents. 

Brian

Yup, agree with BBD and Dgunthert. Growth plates not closed are prone to injury. Good that you were on a track/grass though, that's softer on the joints and pads.

And actually, while they sometimes seem to have some tiny amount of quittin' sense to lay down or stop, they don't really always use it. My corgi stayed with my in-laws for the weekend several years back, and they had a pool. Some friends were over with their kids in the pool. My corgi thought he was in heaven running and barking and chasing the kids and the water... and running and running, and no one noticed that he had ran his feet bloody on the poolside surface until there were lots of bloody footprints. My in-laws felt terrible, the vet could do nothing, and he literally laid on his side the rest of the weekend. His dish was brought to him, he ate laying down. To eliminate, he was carried outside, he stood in the spot he was set down in and peed/etc. Then stood there until he was carried back in and he laid on his side. Poor little idiot.  So if something is really interesting - they got no quittin' sense at all.

The one year old rule makes sense.  Both of my goldens were already older than that when I got them (one from a humane society shelter, the other from golden retriever rescue). The first was 2 when I got her, the other was estimated to be about 1. They would run till their legs fell off, until they got too old (7 or 8). My older dog once (when she was about 2) kept up with me on a 10 mile mountain bike ride (though I never did that with her again). The only time I had trouble was when the younger dog took off and got himself turned around. By the time I caught up with him, he must have covered a good 10 miles, and refused to walk the 2 miles back to the car. Fortunately, we were close to another trailhead, so mrs gearboy stayed with him while I got the car, drove around to the other trailhead, and walked/carried him the quartermile or so to the new trailhead.

If you give him about a year, your lab will drive you into the ground if you try to keep up with his energy.  I'd consider training a HIM or IM if you keep running with him!