Wellington’s Rainy Day by Carolyn Beck and Brooke Kerrigan

From chapters.ca:
It's a rainy day. Wellington is down in the dumps and can't resist the smell of his master's freshly made meatloaf. While his master snoozes, Welly devours every last bite. After he hides the empty pan, he eats the contents of the garbage can too. Honey, a sneaky kitty and Wellington's archenemy, threatens to tell on him. Welly's tummy begins to churn and out comes everything he has gobbled down. What a mess! But in this lively, rhyming picture book, things have a way of turning out better than expected for Welly, and just this once he escapes being blamed for the missing meatloaf.