From: Rabbi Moshe Sofer
To: Rabbi Lizer
The correspondent asked why the Rambam and Shulchan Aruch omit the Beraisa's distinction between horse stables with and without human dwelling for extending city boundaries (ibur ha'ir). The Chasam Sofer defends both rulings: stables need no human dwelling based on a kal vachomer from animal enclosures that permit carrying without one.
Source: Shu"t Chasam Sofer OC §95