Effects of hair coat characteristics on radiant surface temperature in horses

Abstract

Horse owners may lack knowledge on natural thermoregulation mechanisms in horses. Horses are managed intensively; usually stabled at night and turned out during the day, some are clipped and many wear a blanket, practices which reduce the horse' ability to regulate the heat dissipation. The aim of this study was to investigate the relation between hair coat characteristics, body condition and infrared surface temperatures from different body parts of horses. Under standard conditions, body surface temperature of 21 adult horses were investigated using infrared thermography. From several readings on the same body part, a mean temperature was calculated for each body part per horse. Detailed information on horse breed, age, management and body condition was collected. Hair coat samples were also taken for analyses. A mixed statistical model was applied. Warmblood horse types (WB) had lower hair coat sample weights and shorter hair length than coldblood horse types (CB). The highest radiant surface temperatures were found at the chest 22.5 ± 0.9 °C and shoulders 20.4 ± 1.1 °C and WB horses had significantly higher surface temperatures than CB horses on the rump (P<0.05). Horses with a higher hair coat sample weight had a lower surface temperature (P<0.001) and hind hooves with iron shoes had a significant lower surface temperature than unshod hind hooves (P=0.03). In conclusion, individual assessment of radiant surface temperature using infrared thermography might be a promising tool to give horse owners objective management advice, based on the individual horse's actual needs at the time.

Association between the Area of the Highest Flank Temperature and Concentrations of Reproductive Hormones during Pregnancy in Polish Konik Horses—A Preliminary Study

“…In the study presented here, the day of breeding was known, and the mares were monitored over time. In a case of wild horses, the ability to determine pregnancy is limited by lack of knowledge about fact and time of mating [ 24 ]; seasonal changes in the hair coat lengths [ 25 , 26 ], which may affect the thermal properties of the skin and hair coat and, consequently, thermographic images [ 9 , 27 ]; and finally, the environmental conditions during thermographic imaging [ 11 , 12 , 23 ]. Therefore, further research involving measuring the hair coat lengths [ 9 ], comparison of thermal features of brushed and non-brushed lateral surface of abdomen [ 5 ], and comparison of indoor and outdoor thermographic imaging [ 28 ] are required to determine whether the measurement of Area Tmax of mares’ flank may be further investigated as a potential pregnancy diagnosis tool.…”

Advances in Thermal Image Analysis for the Detection of Pregnancy in Horses Using Infrared Thermography

“…Using minimal temperature allowed the detection of pregnancy from the 8th month of gestation [ 8 ], whereas the maximal temperature, average temperature, and Area of Tmax from the 6th month [ 8 , 9 ]. The differences in thermal images were observed specifically in the smaller flank area of the lateral surface of the abdomen as opposed to the whole area of the lateral surface of the abdomen [ 8 , 9 ], probably due to the decreased amount of hair coat growth in the flank area [ 60 ] and thus lower local thermal insulation [ 19 ]. The flank area, therefore, was considered in this research.…”

“…However, some limitations should be considered when using IRT imaging in the detection of pregnancy. The surface body temperature gradients imaged in the abdominal area can be influenced by ambient temperature fluctuations [ 14 , 15 ], other weather conditions [ 10 , 16 ], and individual properties of horses’ body surface [ 17 , 18 , 19 ]. A high level of repeatability can be achieved and maintained in thermal images using standardized conditions of image acquisition [ 20 , 21 ]; however, the length of time it takes to detect pregnancy related surface temperature changes [ 7 , 8 ] and the accuracy of pregnancy detection [ 9 ] limit the application of IRT to the late stage of pregnancy.…”

Thermographic Analysis of the Metacarpal and Metatarsal Areas in Jumping Sport Horses and Leisure Horses in Response to Warm-Up Duration

“…These findings are not surprising because the resting surface temperature in clinically healthy horses is known to be constant while it is measured in constant environment conditions [28]. Generally, the resting surface body temperature of a horse may be affected by such factors as the quality of the ground in the stall, microclimate in the stable, weather conditions or the length and thickness of the hair cover [29,30]. However, the external conditions were stable during the study, and thus they did not influence the obtained results.…”