Mechanical nociceptive thresholds within the pastern region of Tennessee Walking Horses.
BACKGROUND
'Soring' is the term used to describe the application of an irritant to the distal forelimbs of gaited horses with the sole intent of inflicting pain and inducing altered gait, illegally practiced in Tennessee Walking Horses. Objective methods for the detection of limb pain due to this practice are, however, lacking.


OBJECTIVE
To assess whether Tennessee Walking Horses respond to manual pressures<or=10 kg/cm2 and to establish reference mechanical nociceptive thresholds (MNTs) within the pastern region.


METHODS
In 25 mature Tennessee Walking Horses in which no irritant had been applied, MNTs were evoked by a pressure algometer at 4 sites within the pastern region of each thoracic limb by 6 different examiners. The effects of age, sex, weight, height at withers, exercise and hand dominance of the examiners on MNTs were assessed. Correlations between the horse's perceived mental status, tolerance to the procedure and MNT values were also evaluated.


RESULTS
Mechanical nociceptive thresholds<or=10 kg/cm2 were observed in 20% of measurements, of which the mean+/-s.d. MNT was 9.5+/-0.3 kg/cm2. Within 4 pastern sites, the palmar region had the lowest reference MNT value of 19.5+/-3.6 kg/cm2. Subject status, exercise, hand dominance, horse mental status and horse procedure tolerance did not significantly affect MNT values.


CONCLUSIONS
Reference MNTs of the pastern region of nontreated Tennessee Walking Horses provide an objective standard for the evaluation of those potentially applied irritant.


CONCLUSIONS
Pressure algometry, in lieu of digital pressure, can quantify mechanical pressure applied during inspections to detect irritant therapy and provide consistency between examiners.
Haussler
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Gail Holmes Equine Orthopaedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
Behre
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Hill
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D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait / Q000502:physiology; D006734:Horse Diseases / Q000139:chemically induced / Q000175:diagnosis*; D006736:Horses / Q000502:physiology*; D007794:Lameness, Animal / Q000139:chemically induced / Q000175:diagnosis*; D008297:Male; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement / Q000379:methods / Q000662:veterinary; D017288:Pain Threshold / Q000502:physiology*; D010805:Physical Conditioning, Animal / Q000379:methods* / Q000502:physiology; D011312:Pressure; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index