Integrative model for predicting thermal balance in exercising horses.

The research article presents a theoretical model for predicting heat balance in exercising horses. This model takes into account various factors like metabolic heat gain, solar heat gain and evaporative heat loss, amongst others.

Development of the Integrative Model

• The researchers constructed a model to accurately determine the heat balance of horses working in a given environment.
• This integrative model includes several key parameters: metabolic heat gain from physical activities, solar heat gain from exposure to the sun, evaporative heat loss due to sweating, heat loss from the respiratory tract, body radiant heat and heat variations due to convection and conduction.
• The model makes a unique approach to estimating heat loss through sweat evaporation from the skin surface of the horse. Previous models primarily based this estimation on sweat volume loss.

Ambient Conditions and Sweat Evaporation

• One important factor that had not been adequately defined in previous models is the role of ambient conditions on evaporation rate. This model takes into consideration how the environment can affect evaporation.
• The model equates the horse’s skin surface to a body of water. It describes how this ‘water body’ interacts with the atmosphere around it.
• For the purpose of the model, the researchers assumed that equine sweat behaves thermodynamically like distilled water, despite its high levels of electrolytes and proteins.
• The researchers acknowledged that further investigation is needed to confirm these thermodynamic properties of equine sweat. They suggested that the high electrolyte and protein concentration in sweat may significantly affect such characteristics.

Illustration of Variable Significance

• The integrated model depicts all known factors affecting a horse’s thermal balance when working in specific conditions.
• The model also shows the varying degree of influence each of these factors has on the overall model. It provides a clear understanding of the relationships and relative significance of these variables.
• The most significant and critical way for heat loss, evaporative heat loss, is clearly defined and quantified in relation to ambient temperature and humidity.
• The model warns that increasing relative humidity poses a limitation for evaporative heat loss. This limitation becomes more significant in scenarios where horses exercise on treadmills with no airflow.