Hot Dogs: Thermoregulatory function and dysfunction in the racing Greyhound (Canis familiaris) and the rationale for cooling strategies

Authors: Brownlow M, Streckfuss E
Publication: Australian Veterinary Practitioner, Volume 54, Issue 2, pp 83-115, Jun 2024
Publisher: Australian Veterinary Association

Animal type: Dog
Article class: Clinical Article

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Abstract:

The greyhound (GH) is a unique canine athlete that has been selectively bred over millennia for coursing and racing. The GH can utilise oxygen at a prodigious rate, with extremely rapid energy kinetics, enabling it to accelerate from a standing start to maximum speed in a few seconds. The multiple demands imposed by such strenuous exercise require complex coordination between the respiratory, cardiovascular, and neuromuscular systems, and the resulting high rate of metabolic heat production necessitates a finely tuned thermoregulatory system. This is provided by a powerful ‘panting’ mechanism, where variations in breathing pattern determine its efficiency by controlling the rate and direction of air flow over respiratory and buccal evaporative surfaces.

Disorders of thermoregulation referred to in athletic species as Exertional Heat Illness (EHI) occur from very minor to severe and can be potentially fatal. Veterinarians working at racetracks should be aware of the earliest clinical signs and trainers and handlers should be educated in their recognition. Treatment may require proactive management and specific cooling interventions. The concept of 'thermal windows', which are specific parts of the body surface with specialised vascular structures for heat dissipation, are discussed and rationale for cooling interventions suggested. These principles may be applied to other situations of heat stress in non-GH dogs.

Keywords: Thermoregulation Greyhound, Respiratory evaporative heat loss mechanism (REHL), respiratory (panting), exertional heat illness, thermal windows, cooling interventions GHs.

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