The Alberta Society for the Prevention of Cruelty to Animals is defending its decision to not pursue charges against an Edmonton driver spotted on a highway with two dogs loose on top of a truck bed cover.

The Alberta SPCA's investigating officer has closed the file without laying any charges against the driver, the agency confirmed in a news release on Thursday.

That decision has made the agency the target of online "vitriol," said Roland Lines, a spokesperson for the Alberta SPCA.

"We know many people will be upset with our decision," Lines said in a statement.

"I have spoken to people who have witnessed the tragic outcomes that can result from unsafe transport, and I have received many messages demanding we lay charges."

Charges not warranted, organization says

Lines acknowledged it can be "extremely frightening and frustrating" to see animals transported unsafely, but that doesn't mean charges are appropriate in this case.

The dogs were not injured, said Lines, and animal welfare officials are confident the driver responsible will not put the animals at risk again.

The Animal Protection Act doesn't give Alberta SPCA peace officers the ability to write tickets for regulatory infractions, Lines said. Any enforcement action against a person would need to be prosecuted in provincial court. 

"If the animals are unharmed, and if the investigating officer is confident that the subject acknowledges their error and will act differently in the future, a court prosecution isn't necessarily warranted," said Lines.

"The Alberta SPCA has found that the educational value of face-to-face discussions between our peace officers and subjects is effective at changing behaviour."

Animal welfare officers launched an investigation after photographs and video of the incident sparked outrage on social media last week.

Joey Dunbar, who was driving home to Edmonton on Sunday with his wife, said a truck passed them going more than 110 km/h on the Yellowhead Highway. 

'It is reassuring to see that so many people in Alberta recognize the importance of transporting dogs in a safe manner'- Roland Lines

On the back of the truck, sitting above the box on a slip tank or a tonneau cover, two large dogs were clinging to the vehicle. 

Dunbar, who was in the passenger seat, took some video and photos and filed a complaint with police. His post on Facebook was shared more than 50,000 times before it was taken down.

The Alberta SPCA is thankful to those who reported the incident, said Lines. Although the driver won't be prosecuted, Lines said the organization is hopeful that the incident will raise awareness.

"Despite the vitriol in some of the online comments, it is reassuring to see that so many people in Alberta recognize the importance of transporting dogs in a safe manner,"  he said.

"Through continued public education, we hope that the frequency of these situations continues to decline."