I have been involved in a an animal control case, usually the sheriff/humane society has an arrangement with a foster-type facility (or several) for horses, and there is a daily rate charged. You do not get your horses back until you pay the fee owed if they are legally removed by the sheriff (or someone he authorized) to one of those places.
I know this because one of my horses was involved in a trailering accident en route to my farm, and she ended up at just such a facility when the trailer she was in was totalled. It was actually quite a nightmare getting her back, and I didn’t do anything wrong!