Jealousy in humans is a complex emotion. It has been hypothesized that there may be a core or primordial form of jealousy that developed to secure resources and as a survival mechanism for species with siblings. Infants as young as 6 months have shown behaviors suggestive of jealousy when their mothers interacted with a lifelike doll. In this study, 36 dogs and their owners participated in a study modeled from the infant studies. Interactions with owners and dogs were videotaped and scored. Owners ignored their dogs and interacted with 3 objects: a stuffed dog the owners treated as another dog, a novel object (carved pumpkin), or a children’s book with pop-up pages and music. Dogs exhibited significantly more jealous behaviors (snappy, getting between owner and object, pushing or touching the object) when owners interacted with the stuffed dogs. The majority of dogs (86%) sniffed the anal region of the toy dog during and after the experiment. No one behavior was indicative of jealousy, but when all were considered, the authors concluded there was a strong case that domestic dogs have a form of jealousy.