Evaluation of contact heat thermal threshold testing for standardized assessment of cutaneous nociception in horses - co
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RESEARCH ARTICLE
Open Access
Evaluation of contact heat thermal threshold testing for standardized assessment of cutaneous nociception in horses - comparison of different locations and environmental conditions Christin Poller1*, Klaus Hopster1, Karl Rohn2 and Sabine BR Kästner3
Abstract Background: The aim of the study was to evaluate the performance of contact heat thermal stimulation in horses at different body sites and under different environmental conditions and different test situations. Five warm-blood horses were equipped with the thermal probe located on the skin of nostril (N), withers (W) or coronary band (C). Skin temperature and reaction temperature (thermal threshold) at each location were measured and percent thermal excursion (% TE = 100 * (threshold temperature - skin temperature)/(cut-out temperature - skin temperature) was calculated. Environmental conditions were changed in partial random order for all locations, so each horse was tested in its familiar box stall and stocks, in the morning and evening and at warm and cold ambient temperatures. Type of reaction to the stimulus and horse’s general behaviour during stimulation were recorded. The stimulation sites were examined for the occurrence of possible skin lesions. Results: Skin temperatures were significantly different during warm and cold ambient temperatures at all three locations, but remained constant over repeated stimulation. An obvious response to stimulation before reaching cut-out temperature could be detected most frequently at N and W in boxes during warm ambient temperatures. The most frequent type of reaction to thermal stimulation at the nostril was headshaking (64.6%), skin twitching at the withers (82.9%) and hoof withdrawal at the coronary band (79.2%). Conclusion: The outcome of thermal threshold testing depended on ambient temperature, stimulation site and environment. Best results with the WTT2 in horses were obtained at the nostrils or withers in a familiar environment at warm ambient temperatures. Keywords: Horse, Nociception, Pain, Contact heat, Environmental condition
Background Repeatable and reliable tests for detection and quantification of analgesia are essential for development of effective analgesic protocols. Nociceptive threshold tests are standard models of nociceptive pain in laboratory animals [1]. Among different stimulation modalities heat stimuli are widely used in classic tests [2-4]. In horses, contact heat and radiant heat have been used as a quantifiable stimulus to determine temperature thresholds [5-8] or the latency * Correspondence: [email protected] 1 Clinic for Horses, University of Veterinary Medicine Hannover, Foundation Hannover, Germany Full list of author information is available at the end of the article
between stimulation and response [9-12]. A thermode based system for determination of thermal nociceptive thresholds, initially designed and validated for use in cats [13], has been adapted for the use in horses [5-8]. When using such systems, definition of a clear cut end-point of st
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