Potter Adam W, Berglund Larry G, O'Brien Catherine
Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42, Natick, MA, 01760-5007, USA.
Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, 10 General Greene Avenue, Bldg 42, Natick, MA, 01760-5007, USA.
J Therm Biol. 2020 Jul;91:102651. doi: 10.1016/j.jtherbio.2020.102651. Epub 2020 Jun 29.
Military working dogs (MWDs) are often required to operate in dangerous or extreme environments, to include hot and humid climate conditions. These scenarios can put MWD at significant risk of heat injury. To address this concern, a two-compartment (core, skin) rational thermophysiological model was developed to predict the temperature of a MWD during rest, exercise, and recovery. The Canine Thermal Model (CTM) uses inputs of MWD mass and length to determine a basal metabolic rate and body surface area. These calculations are used along with time series inputs of environmental conditions (air temperature, relative humidity, solar radiation and wind velocity) and level of metabolic intensity (MET) to predict MWD thermoregulatory responses. Default initial values of core and skin temperatures are set at neutral values representative of an average MWD; however, these can be adjusted to match known or expected individual temperatures. The rational principles of the CTM describe the heat exchange from the metabolic energy of the core compartment to the skin compartment by passive conduction as well as the application of an active control for skin blood flow and to tongue and lingual tissues. The CTM also mathematically describes heat loss directly to the environment via respiration, including panting. Thermal insulation properties of MWD fur are also used to influence heat loss from skin and gain from the environment. This paper describes the CTM in detail, outlining the equations used to calculate avenues of heat transfer (convective, conductive, radiative and evaporative), overall heat storage, and predicted responses of the MWD. Additionally, this paper outlines examples of how the CTM can be used to predict recovery from exertional heat strain, plan work/rest cycles, and estimate work duration to avoid overheating.
军犬（MWDs）常常需要在危险或极端环境中执行任务，包括炎热潮湿的气候条件。这些情况会使军犬面临严重的热损伤风险。为了解决这一问题，开发了一种双室（核心、皮肤）合理热生理模型，以预测军犬在休息、运动和恢复过程中的体温。犬类热模型（CTM）利用军犬的体重和体长输入来确定基础代谢率和体表面积。这些计算结果与环境条件（气温、相对湿度、太阳辐射和风速）以及代谢强度水平（MET）的时间序列输入一起，用于预测军犬的体温调节反应。核心温度和皮肤温度的默认初始值设定为代表平均军犬的中性值；然而，这些值可以进行调整，以匹配已知或预期的个体温度。CTM的合理原理描述了通过被动传导，核心室的代谢能量向皮肤室的热交换，以及对皮肤血流量以及舌头和舌组织的主动控制应用。CTM还通过数学方法描述了通过呼吸（包括喘气）直接向环境散热的情况。军犬皮毛的隔热特性也被用来影响皮肤的散热和从环境中的吸热。本文详细描述了CTM，概述了用于计算热传递途径（对流、传导、辐射和蒸发）、总蓄热以及军犬预测反应的方程。此外，本文还概述了CTM如何用于预测运动性热应激后的恢复、规划工作/休息周期以及估计工作持续时间以避免过热的示例。
