Side-striped jackals (Canis adustus):
I think that it is very likely that some of the reports of “dog/fox hybrids” in Britain from the nineteenth and early twentieth centuries are actually these animals.
When the sun never set upon the British Empire, it was commonplace for creatures native to the far reaches of the realm to be imported as pets for menageries. If any of these animals escaped or were released into the countryside, it is very likely that they would be misidentified as dog/fox hybrids.
Side-striped jackals are in the genus Canis, which makes them close relatives of domestic dogs (although certainly not as closely related as dogs to wolves, coyotes, and golden jackals).
They have some fox-like features, especially that long tail, which is covered in thick fur and is tipped with white. They sometimes have a reddish tinge to their coat, which is somewhat reminiscent of that of a red fox.
Of course, red foxes (genus Vulpes) cannot hybridize with domestic dogs. I’ve seen dogs that look like foxes, and one breed of toy spitz is actually called a Volpino because of its similarity to the fox.
I might be in the minority here, but I think we should move black-backed and side-striped jackals out of the genus Canis and back into Thous, the archaic genus for jackals and coyotes.
I say this because golden and Simien jackals (Ethiopian wolves) have both been found to be very close relatives of wolves and coyotes and are far more closely related to those animals than they are to black-backed and side-striped jackals.
I think it makes sense to put these two “Africa only” jackals into their own genus.