The presence of carriage horses in New York City continues to make headlines periodically, as city officials, animal welfare activists, and celebrities add their voices to the debate. The argument dates back to 2007, when the first bill to ban the carriages was introduced with the support of several politicians and animal welfare groups, who said the horses were overworked, placed in dangerous, stressful conditions, and not cared for in retirement. Pro-carriage supporters have countered that the horses are well-managed and have a number of city codes in place guiding their welfare.
In research presented at the 2015 American Association of Equine Practitioners Annual Convention, Dr. Sarah Mercer-Bowyer of California's Western University of Health Sciences sought to learn more about how the horses process their urban environment, and whether their lifestyles do indeed cause them stress. Mercer-Bowyer and her research team used three parameters to measure stress at different times of the horses' workdays—glucocorticoids from manure, cortisol from saliva, and thermography scans.
Glucocorticoids are steroid hormones made by the adrenal gland that guide the utilization of carbohydrates, fats, and proteins stored in the body. They are known to have anti-inflammatory effects and are released in response to stress, the idea being that an animal suddenly finding itself in danger needs to tap into its energy resources in order to escape. Cortisol is a type of glucocorticoid, and measuring both in manure and in saliva gave researchers a sense of the horse's overall stress level, as well as its current, more acute state.
Thermography produces the rainbow-colored images often seen of the brain or body, showing areas of heat indicating activity. The researchers in this study used a non-invasive machine to measure the amount of activity around the horses' eyes to look for changes that could be related to stress at different points in the day. The sympathetic nervous system, which manages the body's fight or flight response, would cause an increase in the horse's temperature if activated, easily measured on the animal's face.
Mercer-Bowyer examined five horses vacationing on a farm outside the city and 13 working horses over three days, taking measurements at rest, as they were tacked up for work, returning from work, and one hour after leaving work. The researchers could find no difference between the working horses and those on vacation in terms of fecal stress measurements. There was a slight increase in salivary cortisol immediately after the horses returned to the barn after a day at work, but the levels remained the same throughout the rest of the day and were not considered unusually high at any point. The variation could have been explained by a natural change in metabolism as a result of their time on the clock. There were no unusual findings related to the horses' temperatures during their workdays, either.
The data seems to indicate that carriage horses do not appear to 'worry' about their shifts, and don't seem to come back from work on the city's streets nervous and overwrought. Mercer-Bowyer added that the horses seemed outwardly relaxed and well-fed, having settled into a comfortable routine with their handlers.
“The results of our study indicate that the carriage horses' lifestyle is not negatively impacting their well-being,” said Mercer-Bowyer. “When you look at these findings alongside the impeccable care these horses receive, it becomes clear that this is not an equine welfare issue.”
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