The ute driver's friend would not give her name for fear of identifying him.
She said the story about the dog's death should not have been published because the driver was not able to give their side.
"Their dog was their best loyal friend," she said.
"There are two sides to every story. The person has read that story and has realised what has happened and been incredibly distraught."
SPCA animal welfare inspector Lesley Gibson said she still wanted to identify the driver. The SPCA had not received any calls about the incident.
"There must be someone out there who knows something," Mrs Gibson said.
She said she hoped the driver had learned from the experience. "It's the woman who witnessed the whole thing that I feel sorry for. She has to live with what she saw."
Mrs Gibson said owners who carried their dogs on the back of vehicles needed to keep them on a short lead. Contact the Masterton SPCA, phone 06 377 1912.