Though a dog's emotions are not as complex as a human's, he still feels them -- and that includes negative emotions. Your behavior can hurt your dog's feelings, causing emotions like jealousy, fear and sadness. Just as you would with another human, you must make sure that you are fair and kind with your pet, or his hurt feelings can add up to mistrust.
Dogs and Emotions
Dogs don't think about their feelings, but they still feel them. For example, if two dogs perform the same trick and only one is given a treat, the other will sense the inequity -- if you keep it up, he'll stop doing the trick, because he realizes that he isn't getting equal treatment. If you consistently reject your dog's attempts at sharing affection or getting attention, he may become despondent and listless -- he craves interaction with you. Dogs that live in cruel conditions may develop fear and mistrust of humans after being subjected to emotional and physical mistreatment. All of this goes to show that you can indeed hurt your dog's feelings, and you should treat him lovingly and with respect.