The unconditional love from a pet to owners causes deep emotional reactions, said Nielsen, who helps clients deal with the grief of losing a pet.“It’s profound because you are you're making a decision to actively take the life of your animal,” Nielsen said.

Former NFL quarterback Tim Tebow posted a heartbreaking video of himself saying goodbye to his beloved dog, Bronco, before putting him down Wednesday night."For so many people, (dogs) are our best friends and they provide so much joy and love," Tebow told last year.