Why does Carlson suggest shooting Candy's dog ?

Carlson suggests shooting Candy's dog because he stinks.

"God awmighty, that dog stinks. Get him outa here, Candy! I don’t know nothing that stinks as bad as an old dog. You gotta get him out."

"Well, I can’t stand him in here," said Carlson. "That stink hangs around even after he’s gone." He walked over with his heavy-legged stride and looked down at the dog. "Got no teeth," he said. "He’s all stiff with rheumatism. He ain’t no good to you, Candy. An’ he ain’t no good to himself. Why’n’t you shoot him, Candy?"

what happen that made george stop playing tricks on lennie?