For thousands of years, Dogs have been “man’s best friend” and they were well known in the ancient world. Dog, being a domestic animal can even be found in several different episodes in the Bible, such as the faithful dog of Tobias (Tobit 5:16) — although frequently, they are mentioned in a negative way, as wild dogs and scavengers.
But when it came to depicting dogs in medieval art, the dog took on some of its classical attributes of watchfulness and fidelity.
Most times dogs would be drawn next to a married woman, symbolizing her faithfulness. (Little wonders, why one of the most common names for a pet dog through the centuries was Fido — which in Latin means “faithful.”).
Other times dogs were however, seen as healers by virtue of the natural properties of their tongue.
One commentary like that explains, “The ability of dog to heal wounds by licking them and this represents how the wounds of sin can be cured by confession. In the other way, a dog returning to its vomit signifies those who make confession but then return to their sinful ways.”
A 14th-century patron known as St. Roch, invoked against the plague, which is often pictured with his miracle-working dog, who healed sores by licking them.
Later on, black and white dogs became the symbol of the Dominican order or St. Dominic. This is partly due to a Latin phrase (Domini canes, which means “dogs of the Lord”) that nearly resembles a Latin name of a Dominican friar (Dominicanus).
However, there is this story from the life of St. Dominic which said his mother had a dream that she would give birth to a dog with a torch in its mouth which would set the world on fire.
An English poet, Francis Thompson wrote in one of his poems entitled “The Hound of Heaven,” which portrays God as a dog who continually goes after the wayward soul to bring it to redemption.