Dog Zero is the unseen leader of the Spy Dogs. His appearance is never shown, but he is probably a bloodhound.
Dog Zero is the smart leader of the Spy Dogs. He is very intelligent and knows exactly what has been going on during missions. He is very vigilant and alert. Although he is not seen, the Spy Dogs and the viewers can still hear him. Sometimes, they wonder who his true identity is.
Dog Zero's true identity was never shown, but he could be a bloodhound. His appearance is never shown in the series. He is always at mission control, so his identity is never seen.