This is our mind’s first response to the death of our pet. It’s difficult to even comprehend the absolute reality and we become overwhelmed with numbness. With the initial shock, we tend become defensive in order to protect ourselves. Then disbelief sets in, we are consciously unwilling to accept the truth. This however changes with time and after a few hours, or days, we acknowledge the death. This is all normal.
Denial on the other hand is our mind refusing to accept reality. It is unconsciously to painful to bear the pain. Some may even bargain with God, making deals in hopes that the pet will come back again. Denial may serve as a “temporary band-aid” for immediate protection. It should however be a quick temporary state. But in the event that it becomes a prolonged mindset, professional help should be sought out.