This mare's clitoris is "winking" (everting frequently) which is taken as a sign of heat (receptive to the stallion). It also occurs at the end of urination.
A 100 watt incandescent (cannot be fluorescent and not sure about LED) light bulb sets above each stall and is plugged into a timer to provide adequate amounts of light to fool the pituitary gland into thinking the amount of daylight is increasing. This helps mares to start cycling and for the winter hair coat to shed in both genders.
