Protecting Working Dogs and Canine Athletes from the Negative Effects of Hyperthermia

Working dogs perform important tasks such as search and rescue, detection of dangerous chemicals or parasites, assisting law enforcement, and more. These dogs are at risk for heat exhaustion and heat stroke because they produce a lot of body heat during work and may need to work for prolonged periods of time in hot environments. To protect the safety and welfare of these working dogs and all elite canine athletes, the AKC Canine Health Foundation (CHF) provided funding to study the effects of physical fitness on the efficiency of skeletal muscle energy production in dogs (CHF Grant 02646: Effect of Hyperthermia on Skeletal Muscle Energy Efficiency).

Investigators at Oklahoma State University studied skeletal muscle biopsies from six Alaskan sled dogs before and after a seven-month period of training and racing to represent low and high levels of athletic conditioning. Their theory was that athletic conditioning improves cellular tolerance of increased body temperature, known as hyperthermia. If true, this knowledge would inform handlers, trainers, and veterinary professionals to maximize physical fitness in working dogs so they can work harder in hot environments without overheating. Results of their study were recently published in the Journal of Applied Physiology¹ and provide unique insights regarding how dogs manage the physiologic stress of hyperthermia.

An organelle is a subunit within a cell that performs a specific function. Mitochondria are one type of organelles and generate most of the chemical energy needed to power the cell's biochemical reactions. Since these mitochondrial processes are the source of heat generation during exertion, investigators examined skeletal muscle mitochondria for any physiologic changes in response to hyperthermia. Results were surprising in that with increased athletic conditioning, efficiency of the main energy generation process within the mitochondria decreased. This finding differs from previous studies in humans and horses. Investigators suggest that while a decrease in efficiency seems counterintuitive, it may decrease the number of dangerous reactive oxygen species produced during exertion and therefore decrease oxidative damage to the mitochondria.

These findings demonstrate a novel adaptation to physical exercise in dogs and warrant further study. Future research will explore if and how these cellular adaptations improve exercise performance and recovery. The AKC Canine Health Foundation and its donors remain committed to studies like this to protect and improve the health and safety of working dogs, canine athletes, and all dogs. Learn more about our research at www.akcchf.org/research.

1. Davis, M. S., & Barrett, M. R. (2021). Effect of conditioning and physiology hyperthermia on canine skeletal muscle mitochondrial oxygen consumption. Journal of Applied Physiology.
   https://doi.org/10.1152/japplphysiol.00969.2020