Effects of Time of Day, Ambient Temperature and Relative Humidity on the Repeatability of Infrared Thermographic Imaging in Horses. (September 2015)

• Record Type: Journal Article
• Authors: Satchell, G.; McGrath, M.; Dixon, J.; Pfau, T.; Weller, R.
• Is Part Of: Equine veterinary journal. Volume 47:S48(2015:Sep.)Supplement
• Page Start: 13
• Page End: 14
• Publication Date: 2015-09
• Subjects: Horses -- Diseases -- Periodicals; 636.108905
• DOI: 10.1111/evj.12486_30
• Languages: English
• ISSNs: 0425-1644

Abstract

Abstract : Reasons for performing study: Infrared imaging is becoming popular as an aid to traditional diagnostic tools, its repeatability under practically relevant conditions is still discussed. Objectives: We hypothesise that time of day, ambient temperature and relative humidity affect thermography readings, and that there is no difference between values from left and right side. Study design: Repeated thermography in a convenience sample. Methods: Fifteen sound horses were thermographically imaged at 3 time points in the same day (08.00, 12.00 and 16.00 h). Images were taken of the following regions: neck, carpus, distolateral thoracic limbs (cranial and tendon areas), thoracolumbar, pelvis, hock and pelvic limb tendons. Relative humidity and ambient temperature were recorded for each session. Results: There was a significant difference between the temperature readings during the 3 imaging sessions in all areas (Friedman and Kruskal–Wallis; all P<0.014). Ambient temperature and relative humidity correlated with thermography readings in the caudal imaging areas (P<0.008 [temperature], P<0.032 [humidity]) of the horses, with an exception of one hock reading, but not in all cranial areas (P<0.365 [temperature], P<0.992 [humidity]) (Spearman's Rho). All but 2 regions (minimum values in the carpus and thoracic tendon areas in the morning session, (P = 0.033, 0.034) did not show significant difference between left and right sides at the same time of day (all P>0.057). Conclusions: Time of day, ambient temperature and relative humidity must be considered when using infrared imaging. Variations between the left and right sides of the horse can occur and should be considered during the analysis of pathological asymmetry. Ethical animal research: Ethical approval was granted from the Royal Veterinary College Ethics and Welfare committee as part of the first and second author's final year research project.Source of funding: Funding was provided by the Royal Veterinary College as part of the first and second authors' final year research project.Competing interests: None declared.