Let her know that you plan on putting a notice in the newspaper regarding the debt that you will be naming her and the amount of debt owing for the care and feeding of one (color) commonly known as (horse's name). Also add that if the debt is not repaid by (date) the horse will be sold at public auction. In the meantime lock up all her stuff, get it out of the barn. She may pull a midnight skulk and remove the horse. In Ontario we can do as mentioned above but if the sale of the horse exceeds the debt plus reasonable expenses the remainder must be given to the owner. I really doubt you will get your money, even thro court as I suspect she just doesn't have it. OR, have her sign the horse over to you in lieu of debt.