This is an example of a "supposedly" barren mare showing nearly continuous, but faint estrus after she arrived at the breeding farm. The owner of the mare indicated that he had purchased her from a breeder after she lost a foal and had been unsuccessful in getting her to cycle and settle. She was reasonably well bred and the owner had her shipped to the farm to be placed under a 16 hour light regime to encourage early cycling. Although faint heats in some mares are not unusual, this mare's ovaries upon rectal examination continued to stay small, nonfunctional and hard. Even when the mare showed a "quasi-heat", her ovaries remained more like those of a mare in deep seasonal anestrus. After an extended period of time under lights, the mare was still acyclic and the owner was called again. Upon further questioning, he indicated that he had not actually seen this mare's foal, but had only taken the previous owner's history when he purchased the mare. With no confirmed history of a previous pregnancy, that opened up other avenues of investigation to explain this lack of cycling behavior. First on the list to be eliminated was a genetic condition called Turner's Syndrome. These mares are externally normal in appearance, but lack both X sex chromosomes. A normal male would typically have sex chromosomes from both parents comprised of an X and a Y, while a normal female is XX, but a Turner's Syndrome mare is XO (X and a nothing). Blood samples were drawn from the mare and the results were positive for Turner's. Based on the exam of the chromosomes, the mare was diagnosed as genetically sterile and further efforts to breed her ceased. The major lessons learned from this experience were to not completely believe all mare owners in their recitation of breeding history.

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