Destruction, inappropriate elimination and incessant vocalizing are common signs of a separation issue. However, they must be assessed in context with the rest of a dog’s behavior. Here’s an excerpt on the subject from a book sold by Whole Dog Journal. It’s up to you if you want to buy it, but the recommendations are good to discuss with pet owners.
Source: Whole Dog Journal January 10, 2017.
One identifying factor in the diagnosis of a true separation issue is that stress-related behaviors occur every time the dog is left alone.