I’ve got a 12 year old cairn terrier. We’ve never done the roller blade or biking thing together, but he goes hiking quite a bit. The places we’ve gone where it’s more wooded and he’s had access to creeks to wade in, with temps in the high 80s/low 90s, he’s shown no effect. He’s easily done 5 miles. Course that was with us carrying 50lb worth of backpacks, so we were taking breaks every mile. But he never looks even remotely tired or hot, compared to the exhausted souls holding onto the leash.

However, when we’ve gone hiking in high 70s/low 80s on Enchanted Rock in TX, that has lil’ cover from the sun, with the heat coming up off the rocks, we do have to be more careful. We’ll take breaks every 10-15 mins, give him a drink and toss some water on him, and if he starts to look tired, we’ll carry him back to the car. The last time we went, between me and my friend, I bet we carried him 2 miles back to the car, climbing up and down rocks.

I should add that we recently put a brick path in my backyard, in the heat of the day with the sun blaring down on us, with temps in the 90s and he was outside with us. Was he relaxing on the nice shaded patio? Uh no… He spent 4 hours nonstop chasing flies around the patio. He kept jumping up and down off my workbench trying to get closer to them. He’d go get a drink ever so often, but he didn’t even remotely look tired or hot. So with him it really seems to matter most if the sun is hitting him directly and not so much the actual temp and level of activity.

As far as symptoms, I guess I’d look for increased panting and tongue hanging out excessively, but we never let Murph get to over heating symptoms. He normally trots out in front of me, trying to explore as much as a dog can from a leash. As soon as his pace drops down to where he’s even or slightly behind my stride, that’s when we call it quits for the day, because I know for him that means he’s tired. So best to stop before he gets overheated.

Roller blading or biking early in the morning or in the evening, would be your best bet for steering clear of problems with the heat though.

Par…