A Randomized Cross-Over Study Comparing Cooling Methods for Exercise-Induced Hyperthermia in Working Dogs in Training

Simple Summary Working dogs are at high risk of heat stress and heat stroke, as they often are required to perform physically demanding tasks for long periods of time. Handlers' intervention upon noticing signs of heat stress can prevent more serious consequences for the dog. This study assessed the effectiveness of two different, easily implementable cooling interventions that handlers could use with their dogs: partial water immersion and isopropyl alcohol application to paw pads. While both interventions were more effective than no intervention at all, partial water immersion cooled dogs faster and led to an overall cooler temperature in dogs post-exercise than isopropyl alcohol application. Isopropyl alcohol additionally raised dogs' heart rates significantly more than partial water immersion or no intervention, which may be due to its aversive odor and potential for topical irritation. As such, partial water immersion is preferred over isopropyl alcohol for cooling dogs after exercise. Further studies are required to explore the extent to which dogs must be immersed in water and the effectiveness of other water-assisted cooling methods like cooling towels.Abstract Working dogs are at a high risk of canine non-pyrogenic hyperthermia, a life-threatening condition that can occur due to physical exertion or environmental factors that inhibit dogs' ability to cool themselves. Two frequently recommended cooling methods to reduce body temperature are water immersion and the application of isopropyl alcohol to paw pads. This cross-over study compared the relative efficacy of these methods in 12 working-dogs-in-training with post-exertional heat stress. On each study day, dogs had a physical exam and performed a warm-up exercise followed by sequential recalls in which dogs ran approximately 25 m between two designated handlers for 10 min until they showed multiple signs of heat stress or their core temperature reached 105 degrees F (40.6 degrees C). Dogs' temperature and heart rate were collected after each recall. Dogs completed three study days, and each day, randomly received one of three interventions: passive cooling (no intervention), partial water immersion, or isopropyl alcohol. Post-intervention dogs rested for 20 min. Partial water immersion and isopropyl alcohol both cooled dogs more than no intervention, and water immersion cooled dogs more efficiently than isopropyl alcohol. Additionally, the application of isopropyl alcohol raised dogs' heart rates more than water immersion or no intervention, suggesting that the process of applying isopropyl alcohol is potentially stressful to dogs. Thus, partial water immersion is preferred to cool dogs post-exertion due to its more efficient cooling and better tolerance of use.