Is your horse’s back doing OK? You might want to check again. A study conducted by researchers from the University of Guelph in Canada and the University
of Rennes in France found that only a small number of cases of back pain in horses are discovered by owners and caregivers.
Below are select portions from the research article:
Comparison of clinical examinations of back disorders and humans’ evaluation of back pain in riding school horses
by Clémence Lesimple, Carole Fureix, Véronique Biquand and Martine Hausberger
Background
Back disorders are recognized as a common problem in working horses. The estimated prevalence varies from 27% to 100% of the ridden horse population. Back disorders are difficult to detect on the basis of the behaviour and to evaluate objectively in the field on large samples of horses whether by radiographic, ultrasonic or scintigraphic imaging. As a consequence, horses often continue to be used in athletic activities despite the discomfort/pain. Owners or caretakers may have personal interpretations of behaviours they assume to reflect discomfort or pain. Apart from cases with overt associated lameness or gait alteration, horses mainly express back pain problems through progressive or sudden changes in temperament, such as an increased aggressiveness towards humans, signs of escape attempts, or particular postures at work, in which horses may try to escape back pain.
Methods
Caretakers from 17 riding schools (1 caretaker/school, 161 horses) were given a questionnaire about their horses’ health status, including back disorders. In each riding school, the person who was the most familiar with the horses (the caretaker involved in both daily and health care) was asked to answer questions about whether the horses in their care suffered chronic back pain, lameness, or any other chronic health problem during the past year. Horses had been under the responsibility of this caretaker for at least 1 year. Out of these 161 horses, 59 were subjected to manual palpation of the spine and 102 were subjected to sEMG examination all along the spine.
Manual palpation
Evaluation of the horses’ spine was performed by a 20 years experienced licensed chiropractor, expert in the evaluation of joints and spinal related disorders, who was not familiar with any of the horses beforehand. Manual palpation was performed from head to tail and the 
mobility of each vertebral site was tested (51 vertebral sites: 7 cervical, 18 thoracic, 6 lumbar, 5 sacral and 15 coccygeal). Examination was based on bony and soft tissue manual palpation to localise regions of vertebral stiffness based on spinal mobilisation and palpable areas of muscle hypertonicity.
Electromyography
The sEMG examinations were conducted by the same experimenter, using a wire free device (Myovision®). The device was composed of 2 joysticks with 5 electrodes on each, designed to record muscle activities at the level of the vertebrae at the front and at the back of the joystick location. Muscular activities recorded were sent to a receptor connected to a computer. The joysticks were placed at the level of C2, C6, T3, T9, T17, and L6 on both sides of the spine and the muscular activities at the level of C1, C3, C5, C7, T1, T3, T8, T10, T16, T18, L5 and S1 were recorded. Thus we obtained muscular activity all along the neck, at the level of the shoulder, at the base of the 
withers, at the level of the thoracolumbar joint and at the level of the lumbosacral joint, which are reported in the literature as very likely to be affected with spine lesions. The raw sEMG values were used.
Comparison between practitioner and questionnaire evaluations
Out of the 59 horses, 22% were reported by owners/caretakers as having back pain. According to the manual palpation, 73% of the 59 horses were severely affected (at least 2 vertebral sites affected), 12% were slightly affected (one vertebral site affected) and only 15% were totally unaffected.
The results showed that subjective caretaker-reported evaluation via questionnaire survey was not efficient to detect back disorders: only 19 horses (11.8%) were reported as suffering from back pain, whereas the experimenters’ evaluation detected 80 of them (49.7%) as suffering from back disorders. While most caretakers under-evaluated back disorders, a few “over-evaluated” it. Horses were less prone to present back disorders when under the care of these “over-attentive” caretakers.
Conclusions
This study showed that back pain is difficult to evaluate, even for professionals, and that subjective evaluations using a questionnaire is not valid in this case. The results also highlighted the real need for observational training (behaviours, postures) outside and during riding.
The full article can be found at biomedcentral.com
