Panting

[rpkall]

Hey all,

Thought I would ask this one of the experts. I'm a regular med student... So I'm not sure about this one.

I was thinking about respiratory alkalosis the other day, and I was wondering if the dog-panting-thing causes issues with the pH like it does with human hyperventilation. I would assume (duh) that it does, but if that's true how do dogs get around that? Are they not really ventilating their alveoli enough to blow off significant amounts of CO2, or what?

Sorry if this is an idiotic question. I'd love a brief explanation if anyone has one, though...

Thanks!

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[Bill59]

Panting is not the same as hyperventilation. Dogs pant to enhance heat loss,not blow off CO2 or increase O2 (dogs have few sweat glands). When panting they shift to very rapid but very shallow respirations (low tidal volume). Most of the air movement occurs in the upper respiratory tract (dead space), not in the alveoli where gas exchange occurs. However, this is not perfect and with prolonged panting dogs can become alkalotic.

Another interesting adaptation is that panting usually occurs at a specific frequency (around 300-400 bpm). This is based on the inherent elasticity of the respiratory system and the resonant frequency. This minimizes the necessary muscular effort -- and the associated head production from the muscles. That's why dogs will pant off and on, whether than panting at a slower rate.

 

[rpkall]

Nice.

I figured it was something like that--shallow to minimize trading partial pressures too much in the alveolar compartment.

Thanks!