In the United States, the Animal Welfare Act (AWA) sets forth the minimum space requirements for dogs housed in commercial breeding facilities, but it does not apply to private dog owners. However, many states and cities have their own regulations regarding the minimum size of dog runs.
For example, in California, the minimum legal size of a dog run is 100 square feet for a single dog and an additional 50 square feet for each additional dog. In New York City, the minimum legal size of a dog run is 35 square feet for a single dog and an additional 15 square feet for each additional dog.
It is important to check with your local animal control agency or zoning department to find out the minimum legal dimensions of dog runs in your area.
In addition to the legal requirements, it is also important to consider the size and activity level of your dog when choosing the size of your dog run. A dog that is larger or more active will need more space to run and play.
As a general rule of thumb, a dog run should be at least 10 feet long and 5 feet wide for a small dog, and at least 20 feet long and 10 feet wide for a large dog. If your dog is going to be spending a lot of time in their run, you should also consider adding some features to make it more comfortable, such as a shade structure, a water bowl, and some toys.