Elephants have been known to die of broken hearts if a mate dies. They refuse to eat and will lay down, shedding tears until they starve to death. They refuse all human help.
Scientists are beginning to believe that animals do have emotions and that their feelings may be more intense and unfiltered than our own. Emotion rises from the old brain, the limbic system, which birds and reptiles as well as dogs, humans, and other mammals share. Humans have additional brain structures and symbolic language to process our feelings and a complex array of psychological defense mechanisms that allay or soften the impact of our emotions. We repress, deny, subjugate, dissociate, and use all kinds of conscious and unconscious machinations to separate ourselves from our feelings, but animals have no such recourse, so their emotions are likely to be raw and strong. In fact, this may be one of the reasons we find them so attractive: they wear their hearts on their sleeves, so to speak. People seem to deny the existence of animal emotions so that they can continue to justify inhumane treatment and exploitation and avoid the fact that our actions have a deep emotional impact on our fellow beings.