Although I wouldn't completely rule out a fox, I thought it might either be a bobcat or house cat. The location where the picture was taken is about 10-15 miles from an urban area, but there are lots of ranches and ranchers keep cats to keep the mice and other rodents at bay. The closest ranch to that photo spot was about a mile or two.
Brian in Whitby wrote:
Foxes are sometimes called the cat-like canine. When a fox walks, all the footprints are in a line, one behind the other. They could also be cat, I had assumed the photo was taken away from urban areas and cats were unlikely.