Dog lack extensive sweat glands and therefore rely on evaporative cooling through the respiratory mucous membranes for thermoregulation. This is a relatively inefficient means of dissipating metabolic heat due to the limited surface area that participates in thermoregulation. Thermoregulatory capacity is increased by increased air movement. Defects in a dog’s ability to increase air movement can threaten their ability to thermoregulate.
Brachycephalic dogs by definition have reduced upper airway surface area for evaporative cooling. Furthermore, as a collection of breeds they are noted to suffer from conditions that frequently lead to high upper airway resistance. In these dogs, efforts of maintain ventilation in the face of upper airway resistance results in increased energy expenditure and may also worsen the airway resistance, resulting in a positive feedback cycle that may limit ventilation, and therefore the capacity to thermoregulate. The purpose of this equipment will be to permit the study of the ventilatory responses to mild heat stress in dogs in a non-invasive manner.