In the March 2008 issue of the magazine "The Horse" is an article titled "Horse Management". This lengthy article covers a variety of subjects including one section on "Reducing Back Sensitivity". This article reviews the results of a study that measured and compared pain reduction in horses using several methods.
Researchers used a method known as "pressure algometry" to measure the horses pain responses to pressure. This process utilizes a spring-loaded device with a rubber tipped plunger that measures on a gauge the pressure applied to the horses back. The device measures "mechanical nociceptive threshold" (MNT) which is the pressure at which a horse reacts to pain from the pressure.
A higher MNT means that more pressure is needed to cause pain to the horse and therefore the horse is less sensitive and probably less painful.
The researchers used 38 healthy horses with no history of back pain. They separated these horses into five groups, each of who got a different type of care or treatment. In this study seven got a horse pain medication called "Bute". Eight received massage, seven got no treatment but continued to be ridden, eight also received no treatment but were placed in a pasture to rest, and eight of the horses received one chiropractic adjustment.
MNT evaluations were performed on various areas of the horses on Days 1, 3, and 7, and the results from each group were compared. The results showed that the horses who were given the pain medication Bute had a negative response showing an increased sensitivity to pain on days 1 and 3. By day 7 these horses did show improvement by registering an 8% MNT reading on average. The horses that got massage showed improvements of 8%, 9%, and 12% on days 1, 3, and 7 respectively. The two groups of horses that got no treatment showed almost the same responses with only a 1% improvement on all days.
The group of horses that got chiropractic care showed a slight increase of 1% sensitivity to pain on the first day. However, on day 3 the horses that got chiropractic showed an 11% improvement followed by a 27% improvement by day seven.
Study author Kevin Haussler, DVM, DC, PhD, assistant professor within the Department of Clinical Sciences at Colorado State University, summed up the results by saying, "Massage was beneficial throughout the study; Bute had negative effects for 3 days, then it had a positive effect; and chiropractic had a negative effect (1%) on the first day but then it had the most positive effects."