> You are both right to some extent.  A horse who is not in condition 
>will have an elevated respiratory rate when it comes into the vet check 
>and may stay elevated for an extended period of time if it is exhausted.  
>Some of that may be simply due to psycological stress and/or habbit.  
>Another sutuation is if they have been charging up a hill, creating lactic 
>acid.  Hyperventilating can neutralize some of that acid by blowing off 
>a lot of carbon dioxide.  True panting, though, is to cool the body.  Air 
>rushing in over the intricate scrollwork of mucus membrane tissue will 
>cool the blood.  Exhaling the warm, moisture-laden air will carry off 
>a lot of heat.  The trouble is when the air temp is greater than 105 or so, 
>panting won't help much.  Cool water, and lots of it, over your horse will 
>help minimize the panting.  Even if the humidity is such that not much 
>evaporation takes place, at least the cool water will pick up a lot of heat 
>and run off the body.
Exactly.  Which is why ride vets evaluate the quality of the
respiration, and don't just pass/fail by a number (rate in breaths per
minute).  And why riders need to know the difference between elevated
respiration due to metabolic needs, and panting.
Anticipating the question:  A panting horse will be taking rapid,
shallow breaths, and will have a somewhat elevated core temperature
(if the panting is caused by a temperature over about 103 degrees that
is a cause for concern and the horse should not continue until the
temperature comes down).  A horse in metabolic distress will be taking
deep rapid breaths, and there will be other signs of the distress.
--Joe Long jlong@mti.net http://www.mti.net Business http://www.rnbw.com Personal