I have never encountered this with poms but I have seen this at a top breeder of shitzus in my area. My daughter brought her shitzuh to be rated as she had bought it in Ottawa, Ontario and we did view a sweet little female without a tail. It just happens. Many of this breed at this kennel known to breed only from a line of Grand Champions that appeared at the Westminster shows suddenly turned up with one possibly more. You can have a perfect female and a perfect male and still encounter flaws, it is genetics just like in humans. These puppies are sold as pets usually at half their worth but also with no breeding rights. People do breed them but you are unable to register them and if found out the original breeder can cause monetary damage. Take care, RR