Sentence 1: Mack was a large black lab puppy. 
 Sentence 3: One night, his gas was so atrocious that I moved to the couch to sleep 
 Sentence 4:  I could smell it all the way into the living room 
 Sentence 5:  Eventually he joined me on the couch 
 Given Sentence 2: He slept in bed with me every night, but his gas was terrible.