What causes the conflict when Mr. Lockwood leaves Wuthering Heights in Chapter 2?

Mr. Lockwood suggests he will have to stay the night because of the snow, and Mr. Heathcliff reprimands him for making the trip over in this weather. Disgusted, Mr. Lockwood makes a run for it but is attacked by Joseph’s dogs until Zillah, the maidservant, breaks up the fight and brings Mr. Lockwood inside.