Cronin, who said the dog was chained to a crate, posted the video on Facebook. The video has been viewed more than 2 million times.
People commenting on the Facebook post said they sent the video to authorities in Flagler County. Others expressed anger and asked the woman why she did not call 911.
The owner of the dog told Action News Jax that he didn't think he did anything wrong and that the dog prefers to ride on top of the cage rather than inside it.
Action News Jax reported that the speed limit on the highway is 70 mph.
After seeing the video, St. Johns County animal control officers said they planned to conduct a wellfare check on the driver's animals in St. Augustine, where he lives.