I would not dock a tail if that is what a buyer wanted, but would want a minimum of 1/2 of the purchase price (non-refundable if they decided they did not want the dog).  Definitely would be a contract written.  I think that would cover the Seller because they could then offer a discount to resell the dog and I would not want to be unjustly enriched by the situation and would refund any amount over the discount I had to give to the new purchaser.     |