Anticipatory grief
The five stages namely, denial, anger, bargaining, depression, and acceptance proposed by Elisabeth Kübler-Ross in her model of grief describe the process by which people undergo after a loss. Anxiety, dread, guilt, helplessness, hopelessness, and feelings of being overwhelmed are also common. However, it is important to note that anticipatory grief is not simply normal grief begun earlier.
Animal grief
There are different “categories” of emotions known as primary and secondary emotions. Bekoff explains that primary emotions are similar to reflex or something along the lines of fear or fight-or-flight response. Therefore, it is something that animals react to such as loud noises, unknown objects, or odors (Bekoff, 2000). Having primary emotions is crucial because reactions to these are important for an animal's survival. The part of the brain that is responsible for primary emotions is the limbic system (Bekoff, 2000).