Effect of training and rest on respiratory mechanical properties in racing sled dogs.
BACKGROUND
Racing Alaskan sled dogs develop exercise-induced airway inflammation, similar to that reported for elite human athletes participating in cold-weather sports. These human athletes also have airway hyperresponsiveness, but airway function in sled dogs has not been measured.


OBJECTIVE
To compare respiratory mechanical properties in trained, rested Alaskan sled dogs with typical laboratory hounds, and to determine whether subsequent training alters respiratory mechanical properties.


METHODS
Nineteen healthy adult Alaskan sled dogs were compared with five healthy adult mixed-breed laboratory hounds. All dogs were rested for at least 4 months before examination. Respiratory mechanical properties were measured while the dogs were anesthetized and ventilated with a piston ventilator. The mean respiratory resistance and compliance measurements for 20 consecutive breaths were used as baseline values immediately before measurement of respiratory reactivity. Respiratory reactivity was the mean of 20 consecutive breaths immediately after the administration of aerosol histamine, expressed as the percentage change in prehistamine measurements. After the initial examinations, the sled dogs were divided into exercised and controls. Exercised dogs were trained for competitive endurance racing. Both groups were examined after 2 and 4 months of training.


RESULTS
Alaskan sled dogs had greater respiratory compliance reactivity to histamine (77.47 +/- 8.58% baseline) compared with laboratory dogs (87.60 +/- 9.22% baseline). There was no effect of training on respiratory mechanical properties detected in racing sled dogs.


CONCLUSIONS
Racing Alaskan sled dogs have airway dysfunction similar to "ski asthma" that persists despite having 4 months of rest. These findings suggest that repeated exercise in cold conditions can lead to airway disease that does not readily resolve with cessation of exercise.
Davis
Michael
M
Department of Physiological Sciences, College of Veterinary Medicine, Oklahoma State University, Stillwater, OK 74078, USA. msdavis@okstate.edu
Williamson
Katherine
K
McKenzie
Erica
E
Royer
Christopher
C
Payton
Mark
M
Nelson
Stuart
S
D000336:Aerosols; D000403:Airway Resistance / Q000502:physiology; D000818:Animals; D004285:Dogs; D006632:Histamine / Q000494:pharmacology; D018494:Histamine Agents / Q000494:pharmacology; D008170:Lung Compliance / Q000502:physiology; D023421:Models, Animal; D010806:Physical Education and Training; D010807:Physical Endurance / Q000502:physiology; D015656:Respiratory Mechanics / Q000187:drug effects / Q000502:physiology*; D012146:Rest / Q000502:physiology*
D000336:Aerosols; D018494:Histamine Agents; D006632:Histamine