How much vigorous physical activity is ok for my dog?

Hi,

I saw the video on Facebook "Rush and Cindy on a Bike." I like taking my 21 month old GSD Mac with me when I go for runs, and I thought I'd get your opinion and advice, if possible, on how much vigorous physical activity is OK for him.

I started taking him out in April when he was about 15 months old, and I really love going for runs with him. We start off slow, maintain a fast jog for the most part and always do a cool down walk before we go back inside the house.

So in the beginning we began with 1.75-2 mile runs. During the summer he got a bit too hot, and so we rarely went over this, and I'd take him on walks instead.

On cooler mornings (we go at 5:30-6 a.m.) we would go up to 3 miles. I always made sure to check on his tongue to see how much it was lolling and adjusted accordingly. He also let me know by sitting down/slowing down if he got hot.

Now that the weather is getting cool again, I have taken him out a few times for 4-4.5 mile runs. He seems to be fine, and comes back with some energy to spare even. I noticed you took Rush out for 6 mile runs.

Currently we do about three x 3 mile runs and one longer 4.5 mile run per week. The rest are walking days only.

My question is, how long do you think we can safely work up to? I will be training in the spring for longer runs, and am wondering what general upper limit I should be aware of in GSD's. Is 6 miles about it for him to be safe?

Also, I run through the winter. Should he wear booties on ice/snow? Last winter he showed a tremendous tolerance for the cold (gets to about -5 Fahrenheit here in Canada) when we just went on walks, and I would hope he would be OK going on runs depending on the weather conditions. He does have that hair between his pads, and he never showed any sensitivity to the ice or cold.

I would really value your advice, his health and safety is top priority, I really do not want to put him in any danger.

Thanks very much