Separation anxiety is one of the most common behaviour problems, if not the most common, we see in older dogs. A dog that has separation anxiety is very anxious when it senses that its owner is about to leave. When you do leave, it may become destructive, or bark or howl, or urinate or defecate, or dribble a Niagara of saliva. When you return home it probably leaps all over you, the puppy within overwhelming the old dog without.
Many older dogs have a decreased ability to cope with changes in their routine. Any change might trigger anxiety and for some pets, anxiety escalates into pure panic. A dog having a panic attack may run frantically from room to room looking either for you or for somewhere to hide.