Q. How does shutting barn doors and windows affect my horse’s respiratory health? As the winter approaches, we typically shut our barn doors and windows to keep our horses warm, but is that healthy for them?

A. I always like to preface this with, people shut up barns for the most part, for their comfort. Instinctively, when we close up the doors on the barns, and all the windows, we’re doing it because it’s more comfortable for us to muck out a stall or to clean an aisleway or to do whatever, not completely bundled up with our heavy mittens and hats and gloves on. The horses themselves are actually very adaptable. The thermoneutral zone (the range of ambient temperature in which normal metabolism provides enough heat to maintain a consistent body temperature) even on a clipped horse can go down to about 40 degrees Fahrenheit. So, the horses do extremely well in cooler climates. It’s really us as humans that don’t do well in those cooler climates. We want to really be careful when we think about opening or closing a barn that we’re doing it for the horses’ benefit, because if we close it up too tight, we do end up with some air quality issues in those barns.

Whether or not you should close the barn doors and windows on cold nights depends on the barn and how it’s oriented and set up. In some cases we can actually get away without opening the doors if we have enough openings in our eaves. If we have really shut up our eaves and our windows, then we might need to leave those doors cracked to move some air through that aisleway in the center of the barn. It’s really barn-dependent. One of the things that I tell people to look for as an indicator of poor air quality is the amount of moisture that you’re seeing condensed on surfaces first thing in the morning. If you’re seeing a lot of moisture condensing, it means we’re not getting enough moisture out and, so, we probably don’t have quite enough ventilation in that barn. That would be an indication that we probably need to either crack some doors or crack more windows or do something to try and move a little bit more air in that barn.

Editor’s Note: This is an excerpt from a conversation with Dr. Hayes called “Optimizing Barn and Arena Ventilation,” which you can listen to here.