Dr. Jan Willem de Gooijer of The Netherlands is the house veterinarian for the local zoo and the mounted police unit. He also works with KLM Martin Air to assist with the thousands of horses that come through their airport each year.

Along with the University of Utrecht and KLM Martin Air, he did a small study of horses in aircraft transport looking at stress during transport. The group wanted to do something that was non-invasive, and based on some work previously published by Smith, et al, in 2010 that looked at heart rate changes during road transport. They used heart monitors and behavior scores to evaluate stress in nine horses during an eight-hour flight to New York. They measured heart rate, the heart rate R-R interval, and behavior score (0 relaxed to 5 anxious, panicked, stressed). They did not find the interval to be a useful tool in this study, but the other two were very useful. Behavior score did not always correlate with heart rate- there were times that the horse looked calm but the heart rate was higher. High heart rates were recorded during the loading, the taxi to the plane in the jet stall, and turbulence. They found that the highest behavior scores (most stress) were not recorded during loading as they expected- but during turbulence in flight.

The type of jet stall and gender of the horses did not influence the result, and the resting heart rate never returned to baseline levels during the flight.

Conclusion: Air travel (compared to the Smith data for ground transport) is less stressful than road transport and is not a risk to welfare. Heart rate measurement and behavior scores are a good way to measure stress in transported horses