Potty training regression in dogs is when a dog that has been potty trained starts to revert back to having accidents inside instead of going out to do their business. It is also called housebreaking regression.
Potty training regression does not refer to one-off incidents. Dogs can have an accident inside for a variety of reasons. Maybe they are puppies that are still learning, or your dog wasn’t feeling well that day, or they were left alone for too long without a potty break.
When accidents inside the house become a more common occurrence and seem like a pattern of behavior in a dog that has been previously potty trained, that is when it is considered potty training regression.