This is a detail from The Vision of St. Augustine, an oil on panel in the Scuola di San Giorgio degli Schiavoni, Venice. This soulful little dog is courtesy of the Italian painter Vittore Carpaccio (c. 1460-1525/26), a member of the "Venetian school" at that time. Most of his work stays right in Venice, and he is considered a more conservative stylist rather than an innovator, so he's not as well known as others of that school. (For example, Gentile Bellini, much better known, was his teacher.)
Carpaccio's dogs, when you can find them, are often stylized, not always as specifically rendered as this little guy. But he does portray them with a gentle kindness and pity that leads me to think he must have liked dogs very much. Take a look at what's probably his best known piece, Two Ladies, and see what you think about their pets.