That’s the genius of my design with DogMotoSports.com as all of my vehicles have electric motors and brakes. This means I can always regulate the speeds we go. So we NEVER go faster than the slowest dog. This way I can mix senior dogs with younger dogs which I’ve done on many occasions. I also have the ability to carry a trailer to rest a dog in as we ride so if I feel it maybe necessary I will bring the trailer along or my support team will meet me on the trail and give me the trailer then. Also if necessary my support team will meet me and we can put a dog back in the van to rest and meet up later to run some more or be done for the day however the dog feels:) Huskies are amazing athletes and have very a quick recovery time. So usually we take breaks every 2 to 5 miles and they get any rest on the trail they need then which is almost always minimal as they start yelling and howling to go before I’m ready, LOL! Doing this for almost 30 years with huskies at all stages from relatively young to well in their golden years and everything in between, I’ve seen almost all situations so I can read them really well and am prepared for almost anything.