Hit the target's dog was seen briefly during Unexpected Drama, just before Hit the target committed suicide. Stampy attacked him as he lunged towards him. Stampy swung his sword, but he fell down mid air past Stampy. It is unknown whether he was killed or not as he jumped past Stampy. If he did survive, it is presumed that he would have been killed in the explosion of his master's castle. In episode 91, when all the dogs were captured, a cell was empty suggesting he survived and his master left him in there for a while.
When Stampy saw Hit the target in a corridor, he blocked it off. As Stampy mined it, the dog was there ready to attack. He lunged at him, but Stampy swung his sword at him and he fell past him, but it was impossible to tell whether he was dead or not. After Lucky died, no XP could be seen, so it was assumed he survived.
The First Cake
When Stampy and Barnaby freed all the dogs Stampy owned, a cell was seen empty but still locked, suggesting his master had him locked in there for some reason. He did not officially appear, but indirectly.