I dog sit for a Rottweiler and when he was a little pup, we saw him every week day. I started bringing Jackson with us on our walks when the Rottie, Ezekiel, was around 14 weeks old or so. We hadn't seen him for a while until this week, and I think Jackson didn't believe it was the same dog, but they picked up right where they left off. Ezekiel is just too big and clumbsy now (nearly 65lbs already!-- last time we saw him, Jackson and him were about the same size, LOL) to let them off leash together, so we just do a nice leashed walk around the block for 30 minutes together. They both try to play with each other, but Ezekiel may hurt Jackson without even meaning to do so... so for now, just leashed play!
Anyways, check out the difference:
First pic: taken June 25th
Second pic: taken August 27th
Then I added a before and after (so far) of the Rottie.