The dog/wolf sculptures around the Fonte Gaia that stands in the Piazza del Campo in Siena are (I think) copies of the originals. They represent the she-wolf that legend says suckled the twins Romulus and Remus. Romulus went on to found Roma. However at some stage he had an argument with his brother and killed him. It was Remus's two sons Senius and Aschius, who founded Siena. Hence the Sienese connection with Rome's she-wolf.
But back to the fountain. This information from wiki might interest you YP.
The white marble Fonte Gaia was originally designed and built by Jacopo della Quercia, whose bas-reliefs from the basin's sides are conserved in the Ospedale di St. Maria della Scala in Piazza Duomo. The former sculptures were replaced in 1866 by free copies by Tito Sarocchi, who omitted Jacopo della Quercia's two nude statues of Rhea Silvia and Acca Larentia, which the nineteenth-century city fathers found too pagan or too nude. When they were set up in 1419, Jacopo della Quercia's nude figures were the first two female nudes, who were neither Eve nor a repentant saint, to stand in a public place since Antiquity.