EDIT:
Just noticed this topic was also in History & Archaeology [LINK] with many more replies, so I'll share my dogs there....Dog coins should be a more popular topic! I have one of those cheerful Antestius dogs and really enjoy the
type. I've also recently picked up some very interesting & relatively
rare Greek ones (after the
denarius, below).
Below, I've also pasted some of my notes on what
RRC denarii reveal about
Roman dogs:

Although hounds were popular on Greek coinage as well, Roman Republican denarii provide much more varied depictions of the breeds and contexts of dogs in their society. This issue from Moneyer C. Antestius is notable for illustrating what today might be described as a “lion cut,” popular for poodles and other water dogs. The dog itself is sometimes identified as a proto-poodle or water spaniel of some sort – a working dog. The “lion cut” is meant to permit buoyancy and warmth as the dog retrieved fowl from water. A similar breed may be portrayed on the denarius of L. Caesius, but in a distinctly domestic setting, hinting that, already in antiquity, canine coiffure may have been as much about fashion as function.
Here is a new-ish pair I'm excited about. Two AE from Epidauros in the Argolid, both ex-Maleatas
Collection of Epidauros, the second one also ex-BCD
Collection (sold to Maleatas in 1988), with collector tags. The photos are taken from the Nomos 25
auction listing:

Argolis, Epidauros AE Dichalkoi or Chalkoi (16mm, 2.29g, 5h & 14mm, 3.25g, 12h), late 3rd century BCE. Laureate
head of
Asclepius /
Dog Lying right.
To me, the lower
type shows a
dog that's clearly more active -- I suspect it's doing a "play-bow"!
Dogs were considered healing
animals by the
Greeks, both physically (by licking wounds), and because they were companion
animals of
Asclepius, the main healing god. Pausanias claimed that dogs roamed the grounds of the famous Asclepeion at Epidauros (the most famous Temple of
Asclepius in the Greek world). (Snakes were
his other companion
animals, but it seems they knew better than to let snakes bite them for healing purposes!)