Why should the 'emotions' animals can or can not experience have to be like 'human emotions' though? Maybe the dog can be 'sad' in a way that isn't exactly like

Why should the 'emotions' animals can or can not experience have to be like 'human emotions' though? Maybe the dog can be 'sad' in a way that isn't exactly like sadness as experienced by humans, but it's still an emotion, right?