"usually" after 30 days, something is considered abandoned; I know this is a little different when it comes to boarding facilities, but I know if they are found wandering, or someone is noticably NOT caring for them and not living at the residence, after 30 days, they can be presumed abandoned and they can be rescued without consulting owners.
I have a mare that has been wandering around near our campus all day, so before dark, I led her and put her in our extra pasture, with water, and some hay. I am going to be contacting the sheriffs department tomorrow morning, and leaving pics, etc, so that they can get in contact with the owners; I am going to tell the department that after 10 days, the owners will be charged board and after 30, they will have to have some really good excuses as to why they have just left her to her own demise.
This is not the first time this little mare has been loose either; I found her last fall too, and brought her to a different facility right up the road from me. The owners have left her for several weeks at different places (several times), before coming to pick her up...it makes me wonder why they even have her, if they don't care where she winds up for weeks at a time...maybe I can convince them to let me buy her, or donate her to our horse program...
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."