Killer

Killer is a large, black dog owned by Joe Heffley. He appears in Dog Days.

Overview
On Greg's birthday in June,in Dog Days, Killer ate some of Greg's birthday cake, and then threw up the candles underneath the table. Instead of throwing the whole cake away, Susan Heffley just cut away the parts that the dog didn't touch, ruining the birthday experience for Greg.

Trivia

 * In the online version, Sweetie eats the cake instead.