While chatting with my colleague, the topic of the position of dogs in earlier societies came up. The Bible has many references to dogs, but always as filthy creatures not deserving of our affection or respect, it seems.
I know of the Mahabharatha story where a dog follows the king Yudhistra on his way to heaven. The god Indra invites him but forbids him to bring the dog; the king declines the offer saying he can’t abandon his friend. After this back and forth, this is revealed to be a test and the dog is a god in disguise. Now, was the dog considered a faithful companion to the king? Or does the story seek to showcase Yudhistra’s virtues by having him treat all living things kindly and justly, even a vile and unclean dog*? 
That leads to my question: what are the earliest references in literature or arts to show dogs in a positive light (as gods, as man’s companion cum pet, etc.)?
*Dog lovers, relax :). I don’t actually find dogs vile or unclean. I am using the phrase just for an effect.
Anubis, protector of the dead, was usually depicted as a jackal headed humanoid god. He was worshiped by the Egyptians c. 3000 BC and later. Occasionally Anubis would appear as a jackal head to tail.
The Mahabharata, referenced in the OP, dates from 4th to 9th century BCE.
Source: Wikipedia.
Other canine gods: The Gods Must Be Canine: 9 Ancient Dog Deities – Dogster
Not exactly the type or reference you asked for, but there are burials of dogs in Mesolithic (Middle Stone Age) cemeteries in Northern Europe, sometimes indistinguishable from the adjacent human burials in terms of grave goods, burial practice etc. Very highly regarded canines, but possibly as incarnations of shamans, not just as the best hunting dog individuals.
Lots of positive images of dogs in palaeolithic cave paintings.
The Dg gets a bad rap in the ancient Near East, but dogs were definitely Good Guys in ancient Greece. Homer has Odysseus being welcomed home by his aged dog Argos after his twenty years absence. Pretty clearly the Greeks of Homer’s time – about the oldest Greek literature we have – kept dogs, and kept them for their entire lives, even after they ceased being useful. Argos hears His Master’s Voice, wags his tail, and dies. (c. 800 BCE)
Aesop had plenty of fables about dogs, who were clearly Man’s Best Friend in his stories, circa 600 BCE
Out of interest did the Bible ever mention cats? As in domestic moggies rather than rampaging lions?
It may be relevant as to whether the Hebrews were ever in Egypt - which it seems had plenty of cats.
There are lots of other dogs in Greek mythology. Besides Cerberus, the Hellhound (depicted in art as well as literature), there are the hunting dogs of Artemis and of Actaeon (who tore Actaeon to pieces when he got turned into a deer) Sirius “The Dog Star” is supposed to be the hunting companion of the hunter Orion.
Laelaps, according to some, was one of Actaeon’s dogs. There’s a another myth that has a dog named Laelaps who could supposedly catch anything he chased. One day he chased the Teumassian Vixen, who could avoid any hunter. To resolve the paradox of the undefeated Hunter and the unconquerable prey, Zeus turned them into stone in mid-hunt.
I suspect that’s a late story – the resolution of a logical paradox in this way seems unlikely to be a really old or traditional story. I have a suspicion it was inspired by two rock formations that looked sort of like a dog and a fox, and this is the explanation the guides came up with. If you go on a tour of some limestone cave or some western park with massive rocks, or Polar Caves in New Hampshire, you’ll hear similar stories about how the rocks and formations got that way.