For showing, I figured out years ago that I prefer a knit mock turtle neck short sleeved top for summer. They are typically less expensive than a true rat-catcher blouse, so you can afford to have multiples if you spill on your shirt at the show, or the horse uses you to scratch his itchy head. If it gets really hot on show day and the jacket requirement is waived, one is also not supposed to wear a stock tie, so the mock turtle neck gives a much more finished look. I prefer the mock turtle neck to a full turtle neck, but you could try both and see which you prefer. For fall & spring shows, a heavier long sleeved mock turtle neck provides a bit more warmth. And best of all with turtlenecks – – NO IRONING!