Guy Winch writing at Scientific American:
Losing a beloved pet is often an emotionally devastating experience. Yet, as a society, we do not recognize how painful pet loss can be and how much it can impair our emotional and physical health. Symptoms of acute grief after the loss of a pet can last from one to two months with symptoms of grief persisting up to a full year (on average).
I know it’s nearly always taken me much longer than even I would have thought to get over the loss of any of my dogs. Most recently, the loss of Cisco and Cassidy have been particularly difficult.