You know your pal better than anybody else and have a good idea of their energy level. Luke is our smallest (7 lbs) and he walks by my side making sure he takes the least difficult trail, very wise since by the end of the hike he can out run them all since he rationalized his energy. If need be, he knows that his puppy eyes can go far and get him a piggy back ride in our arms. On the other hand Kafka is one of our eldest hikers, at 12 and with arthritis on her knees she hikes 5 days a week with no problem at all. If we notice that any one of our pack members is struggling, we definitely stop and assess the situation while throwing a ball or a stick for the younger rambunctious ones to let who ever needs a break to rest a little. Our priority is to ensure that they are all having a good time. In other words yes any dog is welcome to come on our hikes. We will always give our feedback on how your pup is doing as well as give an honest recommendation on how often he/she should come.