Lucky Luke 19 - On the Daltons Trail - Morris a Goscinny

Rin Tin Can, possibly the stupidest dog ever, is left in charge of watching the jail. Obviously, the Daltons escape and steal horses and guns. Lucky Luke refuses to get involved, but when he witnesses the prison guards' incompetence and Rin Tan Can's lack of brains, he has no choice but to set out on the Daltons' trail of holdups and burglaries.