Okay, so I have a male Labrador Retriever and he is about 12 years old. He never got fixed. Many of my friends came over before and he didn't do anything (all female friends). However, when my one friend (female) comes over, my dog like gets really horny. Today when she came over, he was trying to hump a pillow. He hasn't tried to hump anything in like over 5 years. She has a female dog, which he might have smelled, but so do my other friends. The friend that he gets horny around is kinda a slutty person. She has already been pregnant. She is my only friend that was pregnant already. Does this have anything to do with it? Why does he act this way around her? Please help, this is a serious question.