How big are dogs penises?

The largest breeds, like Mastiff, St. Bernard, Caucasian Ovcharka, Great Dane average a pnis that is typically between 320 and 420cc of volume (measuring from the tip of the erect pnis to just behind the base of the bulbus glandis). The average human has a volume around 150-200cc (though there are certainly some humans with over 300cc volume). As a rule of thumb, dogs have larger p*nises than humans, when comparing similar weights.