How to Tell if Your Older Dog Is over Exerting Itself
To tell if your older dog is overexerting itself, look for signs, like excessive panting or trouble breathing. At this point, let it take a break, especially if it's limping or moving awkwardly, which may be a sign of muscle or joint pain. Additionally, allow it to rest if it's unwilling to continue walking or playing. If you notice that your dog is experiencing more frequent bouts of overexertion, try some activities that are better suited to older dogs, like swimming or indoor training like tug-of-war.
Look for excessive panting and trouble breathing. If your dog is getting winded more easily than it used to then you may need to exercise it less. Problems breathing, coughing or hacking, or lots of panting can be a sign that your older dog is doing too much. Allow the dog to catch its breath and calm down. After the dog has recovered you may be able to continue the activity at a slower pace. Look at your dog's tongue while it is panting. If the tongue is bright red, this means that the dog is overworked and needs time to rest. Some amount of heavy breathing is normal when exercising. However, if your dog is having a hard time catching its breath under very little exertion, then you should get it looked at by a veterinarian. This can be the sign of a health problem that needs to be treated. Notice signs of pain or discomfort. If your dog is limping or moving awkwardly, it could mean that your dog is in pain and has overexerted itself. Many older dogs have joint and muscle issues that can be painful and impact their ability to exercise. If your dog is older then you should be on the lookout for signs of this type of problem. Allow your dog to rest if it shows signs that it is in pain. Schedule a veterinary appointment if the limping does not go away within a day. Pay attention to unwillingness to continue. Don't force an elderly dog to continue an activity it is really refusing to do. If your dog doesn't want to walk any further or play a game with you anymore, then it may be too tired to continue. Let it rest where it is and try to restart the walk or the activity once it has had some time to recover. This is a case of better safe than sorry. In some cases, your older dog may just be stubborn and exertion has nothing to do with its refusal to continue. However, it's better to keep your dog's body safe than to risk overexerting it. Take medical conditions into consideration. If you know that your dog has a medical condition that could impact its ability to do activities, then you need to keep that in mind and adjust your activities. Alter your dog's routine to adjust to its new reality and don't assume that your dog can do everything it has always done. For example, if your dog has always gone on long hikes with you but it is having some joint issues, then you need to adjust your expectations. Take it on short, less strenuous hikes than you used to. Another example is dealing with stairs. If your dog has a health problem that could impact its ability to climb stairs, for instance if it has a herniated disc in its back, then you may need to adjust its routine to avoid stair climbing. This could mean taking a new route on your daily walk, placing ramps in your home, or simply keeping your dog off of stairs in general. Do not stop exercising your older dog. Older dogs need exercise just as much as younger dogs do. However, they just need different types and amounts of exercise. In fact, for an older dog to continue to stay healthy and happy it needs regular exercise to keep its joints, muscles, and bones strong. The key is to find a happy medium between too much exercise and too little exercise. This will differ for all dogs but many older dogs benefit from a simple daily walk. If your dog is losing stamina, your daily walk may even need to transform into several shorter daily walks. Three short walks will be easier on a dog with mobility issues than one long walk. Continue your dog's favorite activities with alterations. Just because your dog is older that does not mean it has to stop doing all the things it loves in order to avoid overexerting it. It does, however, mean that the dog's activities should be altered to take its current health into consideration. For example, keep walking your dog but make the activities shorter if your dog is getting winded. Keep taking your dog to play on the beach but just do it for a shorter time period. Keep your dog active and happy but just alter its activities a bit. Take the temperature and other conditions into consideration. When a dog gets older it will have less ability to cope with extreme conditions, such as hot or cold temperatures. If the weather is bad or extreme, you may want to find a way to exercise your older dog inside or otherwise protect it from the cold. For instance, if the weather is cold out put a sweater or coat on your dog and limit the amount of time it spends outside. If it refuses to wear it, then exercise the dog inside. If the weather is hot, go outside for very short periods, limit your dog's exertion, and make sure it has access to lots of water. When exercising a dog outside you also need to take ice and snow into consideration. A dog with old joints can seriously injure itself with one slip on the ice. Try new types of exercise. There are some types of exercise that are great for older dogs. For instance, swimming can be a great activity for older dogs because the buoyancy of the water allows the dog to move without a lot of pressure on its joints. Also, new types of activities inside your home, such as more tug-o-war or training exercises, can keep the dog active while protecting it from injury. Be careful, however, about your dog's safety while doing a new activity. In the case of swimming, put a doggy life vest on the dog so that it can easily stay afloat even when tired. 
Look for excessive panting and trouble breathing. Notice signs of pain or discomfort. Pay attention to unwillingness to continue. Take medical conditions into consideration. Do not stop exercising your older dog. Continue your dog's favorite activities with alterations. Take the temperature and other conditions into consideration. Try new types of exercise. 