If you have more than one dog - know this: If you give a snack, toy, or hug to one dog, be prepared to give the other one the same thing – or you risk hurting their feelings. Animal behaviorists paired up two dogs at a time, asked each of them to shake with their paw, but rewarded only ONE with a treat.

What happened? The dog that didn’t get a treat became depressed and stopped giving his paw when asked. The researchers say that’s a sign that he was jealous - or hurt - that his buddy was getting better treatment!