A Mutt in a Rut is a Looney Tunes cartoon directed by Robert McKimson, which was created in 1958 and released on May 23, 1959 (with a production code of 1493, a MPAA number of 18948, and a Vitaphone number of 2871).
Elmer is leaving for a day of work. He and his dog part ways as the dog longingly watches him leave for the day. After he turns on the television, Rover sees an odd show about a man discussing what owners tend to do to their old dogs, or dogs they just don't want anymore. They take them out, claiming to go hunting, then shoot the dog, much to Rover's shock. After he looks over to a picture of Elmer, Rover starts to think that Elmer is probably tricking him so that he'll just wind up shooting him when he's too old, much to his anger. So when Elmer gets home, Rover begins to behave in a hostile manner. Such as laying on the bed, and throwing his slippers in the trash.
Elmer throws Rover out of the house, refusing to let him back in until he stops misbehaving. Elmer then sits down with a paper to see that Hunting Season has begun, so Elmer wonders if maybe Rover just wants to go out hunting. He gets up to grab his gun, unaware that Rover is watching him. He happens to overhear what Elmer says and worries he'll be shooting him on this hunting trip, so he starts to make plans on how to rid of Elmer first...
While out, Rover makes multiple attempts on Elmer's life after Elmer tries to get him to get in front of him so that he can chase out some wild animals for him to attempt hunting. First he tries a simple method involving shooting Elmer, but his aiming makes him shoot a wild grizzly bear in the cave Elmer happened to be standing near. Elmer sees the bear and is very happy that Rover saved him, but when he goes to see him Rover runs off to attempt a second kill. Which consists of a wild cat in a box. Elmer decides to sit down and rest, but when Rover releases the violent, wild cat, it attacks him instead of Elmer.
Elmer is very happy that Rover has been helping to keep him safe all day, but Rover refuses to believe he really cares about him and tries a third, and final time to rid of his "neglectful owner". So he sets up a bomb, but notices it wont go off. Rover gets up to check on it and sees that the line connecting the explosive to the trigger box has disconnected. So Rover puts them together, causing the bomb to go off...
A very happy Elmer brings Rover back home and sits him down on the chair to rest his now broken leg. He turns on the television and goes to get him a drink. The man on television continues to say how bad owners are, much to his aggravation. As Elmer returns, he notices Rover is missing and sees him attacking the man on television!
Noticeably, the dog on the title card is differently colored from Rover, the dog in the cartoon.
The scene where Rover places an ACME product behind Elmer, labelled "One Acme wild-cat - Handle with care", and Rover carefully opens the box with a rope from a distance behind another hill, but the wildcat simply runs in circles towards Rover, maims him and scratches him into pieces is similar to the scene in the Ralph Wolf and Sam Sheepdog cartoon, "Don't Give Up the Sheep".
The version of this shown on ABC's The Bugs Bunny and Tweety Show cuts the part where Rover tries to blow up Elmer with some buried dynamite, only to get blown up when he unwittingly connects two disconnected wires on the detonator.
An earlier version shown on CBS' The Bugs Bunny/Road Runner Show left in the dynamite part, but cut the part where Rover tries to shoot Elmer, only to accidentally kill a bear and Elmer thanking Rover for saving his life.