The Effects of Extended Photoperiod and Warmth on Hair Growth in Ponies and Horses at Different Times of Year

The study investigated the effects of extended photoperiod and warmth on hair growth in ponies and horses at different times of the year. It found that extending photoperiod and warmth at the autumnal equinox did not reverse early-stage winter coat growth, while starting one month after the summer solstice maintained the summer coat in horses but not in ponies. Administering extended photoperiod and warmth one month before the winter solstice resulted in shorter and lighter hair coats in horses, but not until after the winter solstice. Extending photoperiod one month after the winter solstice did not significantly decrease hair length or weight in Connemara ponies, although shedding was faster in light-treated ponies. The study concluded that the timing of light therapy initiation significantly influenced coat growth outcomes, with photoperiod being the primary environmental factor, and highlighted the need for temperature-controlled environments in future research.