I have been aware of times where dogs have mourned their masters, as well as, mourning the loss of another pet. My brother had two boxers, both brothers of the same litter. This past week one of them died at age 12. The other boxer keeps looking for his brother and is very sad and lonely. I have heard stories about dogs laying on their owners graves or not wanting to leave their home without their owner, not knowing where he or she, has gone. So I agree that dogs have the sense of loss in them and they have emotions like humans to react in the same ways that we do. The love of a dog is one of the most treasured gifts given to mankind.