Why did Carlson want to shoot Candy's dog so badly?

In this part of part three, the main topic was Candy's old dog. The old dog had belonged to Candy since it was a pup, and now that it had grown old, Candy has became so attached to it. But since it is old, it is missing many things, like the ability to see, eat, and even walk. It also smells awful. Carlson gets back to the house, and immediately smells the dog, and first dawns upon him to tell Candy to shoot it,  "Why don't you shoot him, Candy?" This catches Candy off guard, how could he possibly kill his friend he had been with all his life. But Carlson keeps urging him to kill the dog. Later, Carlson brings it up again, as if it doesn't get off his mind. I think there is a number of reasons why Carlson keeps urging Candy to get rid of the dog. One reason why is because she dog is old and stinky, and there is even a bad smell after he leaves the room. Another reason why Carlson wants to get rid of the dog, is for the mercy of the creature. Carlson thinks, "This old dog just suffers himself all the time." The dog is so old, that it would be a favor for it to be taken out, and there would be no pain. I also think a reason why he was so focused on shooting the dog, was to show how tough he was. He wanted to help his friend Candy by doing a favor of putting the dog out of misery so that Candy wouldn't have to worry. He wanted to show the other guys that he was tough enough to kill the dog that was causing problems for everyone. After a little while Candy finally gives in, but I also feel like Candy was way too peer pressured. Maybe Candy having one of Slim's pups will solve some problems, but it could also lead to some.