Only the death of a parent - and especially a child - resulted in higher levels of prolonged grief.
New research has found that grief following the death of a pet can be just as deep and distressing as grief after the loss of a person.
The study was led by Professor Philip Hyland of the Department of Psychology at Maynooth University, and shows that people can experience clinically significant levels of prolonged grief disorder after a pet dies.
The research found that 93 per cent of people who lost a pet had also experienced the death of a person.
When asked which loss caused them the most distress, more than one in five - 21 per cent - said the death of a pet.
The study, titled No Pets Allowed: Evidence that Prolonged Grief Disorder Can Occur Following the Death of a Pet, defines prolonged grief disorder as involving symptoms such as intense longing for the deceased, emotional pain, guilt, sorrow, and difficulty accepting the death.
It found that 7.5 per cent of people who had lost a pet met the diagnostic criteria for prolonged grief disorder.
That figure is comparable to grief levels following the death of a close friend, sibling, grandparent, or even a partner.
Only the death of a parent - and especially a child - resulted in higher levels of prolonged grief.
Professor Hyland says that despite strong evidence showing people form deep emotional bonds with their pets, current clinical guidelines do not allow prolonged grief disorder to be diagnosed following the death of an animal.
He said guidelines should be expanded, warning that excluding pet loss not only lacks scientific justification, but can leave people feeling embarrassed, isolated, and unable to access appropriate mental health support.
"If people can develop clinically significant levels of grief following the death of a pet, then it is essential that this is recognised in the scientific literature so that mental health professionals can communicate with the public in an appropriate and accurate manner, and people who need, and desire, clinical care are afforded the opportunity to access it,” he said.

Kildare Brings 575 Vacant Social Homes Back Into Use Since 2014
660,000 Fewer Cars Trips Each Day As Active Travel Rises
Naas To Gain Over 250 Car Parking Spaces
IFA Ends Bord Bia Protest As Governance Review Agreed
Kfm Obituary Notices (Monday)
HAP Tenants ‘Won’t Keep Up’ Without Reform, Says Threshold
New Research Strategy to Power Ireland’s Next Economic Model
Pfizer Opens 2026 Apprenticeships in Newbridge