Interesting, but not unprecedented, all species of the Equus genus (horses, donkeys, and zebras) can interbreed, but usually produce sterile hybrids like mules and hinnies. Be interesting to know if that dog-fox hybrid was sterile, and who its parents were.
True, there are hybrids - Ligers, Tygons too - but up until that story, the possibility of it was extremely rare and was thought not to be a thing that could happen.
Foxes are elegant creatures, renowned for their cunning and grace. You may even think they look a little like dogs, with their long bodies and pointed snouts. Foxes are a common sight in many areas, and they often live in areas populated by humans, and therefore also by dogs. If foxes and dogs...
Regardless, to have it genetically proven is interesting as hell.