According to a study discussed on CNN, the anxiety and stress of being alone can can cause premature grayness in dogs. The research was conducted on test subjects between the ages of 1-4, and found that female dogs were more likely to go gray than male dogs.
Pet parents who are concerned about how loneliness may be affecting their dog should consult with their veterinarian. One suggestion is to not leave your dog alone for so long each day. Take them to a doggy daycare for care and attention while you’re not at home.