Your own powers of observation are among the most important tools you have to help keep your dog healthy and happy. Since you alone know your dog better than anyone else, you are in the best position to notice any changes, however subtle, in their appetite, stools, behaviour, appearance and weight. It is important to pay particular attention to behavioural changes as that can be a key sign of a medical problem, especially in an older dog. Keep a watchful eye on your dog for any physical or emotional changes that may arise. You are the most important person in your dog's life!