Supplicia Canum
The Supplicia Canum was a controversial annual sacrifice involving the crucifixion of live dogs. Although not explicitly mentioned on extant Roman calendars, a late source places the event on 3rd August.
Date: 3rd August
Observances: Crucifiction of dogs
The sacrifice of dogs was intended to commemorate a time when geese saved the city during the Gallic siege of Rome. The failure of the watch dogs to bark during the attack led to the annual punishment of dogs as a ritualistic atonement.
The procession associated with the Supplicia Canum involved the temples of Juventas (Youth) and Summanus, an obscure and complex chthonic god of archaic Roman religion. The procession may have taken place in the Circus Maximus.
Digital Maps of the Ancient World 