Is there a square foot requirement for pets?

I have noticed that a lot of people have pets, dogs specifically, in apartments here in CO. When I lived in San Diego that was rare unless it was a tiny breed. What has caught my attention are the sizes of some of the dogs that my neighbors have. I’ve seen a pair of medium sized dogs with one neighbor and really big Dalmatian mix with another. My wife thinks it’s inhumane to have such a big dog in a small apartment. I am inclined to agree, the square footage at our complex ranges from 672 -> 862 -> 944. Is there a law that requires certain amount of space per weight of the dog(s)?