The stages of grieving are universal and are experienced by people from all walks of life but not everyone experiences them all or in the same order. In truth, the process of grief is not a cut and dried process that can be subdivided into strict categories. Mourning occurs in response to an individual's own terminal illness or to the death of a valued being, human or animal. There are five general stages of normal grief and by Dividing the grief process in to these "stages" helps the grief stricken person to understand that their experiences and emotions are perfectly normal. 

In the process of bereavement, each individual spends a  different length of time working through each step and will express each stage with more or less intensely. The five general stages do not necessarily occur in order. We often move back and forth between stages before achieving a more peaceful acceptance of death. The depth and intensity of the mourning process depends on many factors. The age of the owner, circumstances surrounding the death, relationship of the animal to the owner and to other family members, are all significant. Often, the more sudden the death, the more difficult the loss is to accept. Unfortunately many of us are not afforded the luxury of time required to achieve the final stage of grief, but I can not emphasis how important it is that the full grieving process is allowed to take place and not stifled or ignored. Family and friends should be reassured that sorrow and grief are normal, natural responses to death. 
The death of your pet might inspire you to evaluate your own feelings of mortality. Throughout each stage, a common thread of hope emerges. As long as there is life, there is hope. As long as there is hope, there is life.

They may not understand
Well meaning family and friends may not realize how important your animal was to you or the intensity of your grief. Comments they make may seem cruel and uncaring. Be honest with yourself and others about how you feel.  Family and friends should be reassured that sorrow and grief are normal, natural responses to death. If despair mounts, talk to someone who will listen about your animal and the illness and death. Talk about your sorrow, but also about the fun times you and the animal spent together, the activities you enjoyed, and the memories that are meaningful.

A final resting place
If death is sudden or unexpected, a distraught owner may have difficulty in deciding how to dispose of their pet's body. Where possible, you should discuss this while the pet is alive and reach a shared family decision which will not later be regretted. Your veterinarian will explain the options which are available to you but, in general, these fall in to four main categories: burial at home (not permitted in some countries), burial in a pet cemetery, individual cremation (where the ashes are returned to you in a casket), and communal cremation (which is how most pets are routinely disposed of by vets).

The Five Stages of Grieving
1. Denial, shock and Isolation: 
The first reaction to learning of terminal illness or death of a cherished pet is to deny the reality of the situation. It is a normal reaction to rationalize overwhelming emotions. It is a defence mechanism that buffers the immediate shock. We block out the words and hide from the facts. This is a temporary response that carries us through the first wave of pain. The reality of death has not yet been accepted by the bereaved. He or she feels stunned and bewildered as if everything is "unreal."

2. Anger: 
As the masking effects of denial and isolation begin to wear, reality and its pain re-emerge. We are not ready. The intense emotion is deflected from our vulnerable core, redirected and expressed instead as anger. The anger may be aimed at inanimate objects, complete strangers, friends or family. Anger may be directed at our dying or deceased pet. Rationally, we know the animal is not to be blamed. Emotionally, however, we may resent it for causing us pain or for leaving us. We feel guilty for being angry, and this makes us more angry. The grief stricken person often lashes out at family, friends, themselves, God, the Veterinarian or the world in general. Bereaved people will also experience feelings of guilt or fear during this stage.

The veterinarian who diagnosed the illness and was unable to cure the disease, or who performed euthanasia of the pet, might become a convenient target. Health professionals deal with death and dying every day. That does not make them immune to the suffering of their patients or to those who grieve for them.

If you or a family member has great difficulty in accepting your animal's death and cannot resolve feelings of grief and sorrow, you may want to discuss those feelings with a person who is trained to understand the grieving process. Your veterinarian certainly understands the loving relationship you have lost and may be able to suggest animal loss support groups and hot lines, grief counsellors, clergymen, social workers, physicians, or psychologists who can be helpful. Talking about your loss will often help.

Do not hesitate to ask your veterinarian to give you extra time or to explain just once more the details of your pet's illness. Arrange a special appointment or ask that he telephone you at the end of his day. Ask for clear answers to your questions regarding medical diagnosis and treatment. Discuss the cost of treatment. Discuss burial arrangements. Understand the options available to you. Take your time. Both you and your veterinarian will find that honest and open communication now are an invaluable long-term investment.

3. Bargaining: 
The normal reaction to feelings of helplessness and vulnerability is often a need to regain control. If only we had sought medical attention sooner. If we got a second opinion from another doctor. If we changed our pet's diet, maybe it will get well. In this stage, the bereaved asks for a deal or reward from either God, the Veterinarian or the Clergy. Comments like "I'll go to Church every day, if only my pet will come back to me" are common. This is a weaker line of defence to protect us from the painful reality. 

4. Depression: 
Depression occurs as a reaction to the changed way of life created by the loss. The bereaved person feels intensely sad, hopeless, drained and helpless. The pet is missed and thought about constantly.  There are two types of depression associated with mourning. 
The first one is a reaction to practical implications relating to the loss. Sadness and regret predominate. We worry about the cost of treatment and burial. We worry that, in our grief, we have spent less time with others that depend on us. This phase may be eased by simple clarification and reassurance. We may need a bit of helpful cooperation and a few kind words.   
The second type of depression is more subtle and, in a sense, perhaps more private. It is our quiet preparation to separate and to bid our pet farewell. It is best to remember that a simple hug is a powerful thing and sometimes that is all that is needed to ease the moment. 

5.Acceptance: 
Reaching this stage of mourning is a gift not afforded to everyone.  Acceptance comes when the changes brought upon the person by the loss are stabilized into a new lifestyle. Death may be sudden and unexpected or we may never see beyond our anger or denial. It is not necessarily a mark of bravery to resist the inevitable and to deny ourselves the opportunity to make our peace. This phase is marked by withdrawal and calm. This is not a period of happiness and must be distinguished from depression.

Pets that are terminally ill or aging appear to go through a final period of withdrawal. This is by no means a suggestion that they are aware of their own mortality, only that physical decline may be sufficient to produce a similar response. Their behaviour implies that it is natural to reach a stage at which social interaction is limited. The dignity and grace shown by our dying pets may well be their last gift to us.

Recently experiencing the death of a significant person in the owner's life can also affect how the pet's death is handled. Usually, children recover more quickly, while the elderly take the longest. Sometimes, the death of a pet will finally enable the bereaved to mourn the loss of a person, whose death had not yet been accepted.