The Harry M. Zweig Memorial Fund for Equine Research


Vertebral Movements and Applied Forces During Spinal Manipulative Therapy in Horses:
A randomized Controlled Study

Dr. Kevin Haussler

Back problems are an important and common cause of poor performance in horses. Unfortunately, veterinarians currently have a limited ability to help horses with poorly defined back problems. A recent increase in the use of alternative therapies has increased veterinarian and horse owner awareness of additional options for diagnosing and treating back problems. Chiropractic is a conservative treatment that is commonly used to treat back pain and stiffness in humans and horses. Chiropractic techniques use small, rapid forces applied by hand to produce therapeutic effects. Based on veterinary experience and human research, chiropractic techniques have beneficial effects on increasing back motion, and reducing pain and muscle spasms.1-3 The exact mechanisms by which chiropractic techniques cause a reduction in back pain or stiffness is still unknown.4 Measuring the amount of force and back motion will provide scientific insights into these procedures. Comparisons of back motion before and after treatment will evaluate the effectiveness of chiropractic treatment to increase flexibility and reduce stiffness. A pilot study indicated that substantial back movement occurs during chiropractic treatment in horses5 however, long-term changes in back motion were not measured. The therapeutic effects of chiropractic treatment need to be objectively measured in horses. Information from this study will help veterinarians to develop recommendations for better treatment of back problems in horses. The purpose of this study is to measure 3-D back movements during chiropractic treatments and to evaluate long-term changes.

Our study is divided into three separate portions and we plan to:

1)measure back movements during chiropractic treatment in horses using a specially designed instrument developed and tested in a prior study;

2)determine the relationships between the amount of force applied during the treatment and the amount of back motion produced; and

3)evaluate before and after changes in back motion in horses that are treated compared to horses that are not treated.

Ten horses will be used in this study. Surgical pins will be temporarily placed superficially in the vertebrae along the midline of the back. A measuring device will be attached to the pins which will measure the amount of back motion. This technique was used in a prior study in our laboratory and is used in humans and dogs to measure back motion. Normal back motion will be measured at a walk, trot and canter on the treadmill. The horses will then be divided into a treatment and nontreatment group. Chiropractic treatments will be applied near the instrumented vertebrae of the treatment group. A pressure pad will simultaneously measure the amount of force during the treatment. The horses in the non-treated group will not be given any treatment. Before and after comparisons will be made in the amount of back motion to evaluate the effects of treatment. We suspect that the treatment group will have significant increases in back motion compared to the nontreated group. Relationships between the amount of force and the induced back movement will also be measured. One week later the treatment and non-treatment groups will be reversed and the same experiments will be repeated. A follow up evaluation will be made two weeks after the initial measurements to assess any long-term changes in back movements. Measuring back motion and the amount of force applied during chiropractic treatments is required to establish a potential treatment guideline for horses with back problems. The long term goal of this project is to investigate effective treatments and reduce the number of horses with back problems.