Home Current News News Archive Shop/Advertise Ridecamp Classified Events Learn/AERC
Endurance.Net Home Ridecamp Archives
[Archives Index]   [Date Index]   [Thread Index]   [Author Index]   [Subject Index]

[RC] guttural pouch erosion - Susan E. Garlinghouse, DVM

No, this is an entirely different thing, it has nothing to do with the GI tract.  The guttural pouches are an outpouching of the auditory Eustachian tubes leading to the tympanic membranes (ear drums), so they’re located behind the nasal sinuses and a bit above and forward of where the oral and nasal cavities intersect at the larynx.  The eustachian tubes are what you blow air through when you ‘pop’ your ears at changing altitudes, they’re what allow you to equalize air pressure and avoid damage to the membranes.  The enlargement in horses was kind of a mystery for a long time, it only occurs in a couple of species to any significant extent, including horses, rhinos, tapirs and hyrax.  How’s that for an eclectic mix?  They thought the guttural pouches were related to communication, hearing, things like that, but didn’t really know for sure.  A few years ago, they figured out that they’re an evolutionary mechanism for heat loss during exercise.  Horses generate a phenomenal amount of heat during exercise and too much heat to the brain will obviously cause significant problems.  So by circulating arterial blood past the air moving through the guttural pouches, the horse can drop the blood temp about 2-3 degrees by the time it leaves the guttural pouches, and thus protect the brain from reaching a critical hyperthermia.  It’s a good trick.


So it’s a pretty slick mechanism for regulating temperature (and obviously, the horse has lots of other thermoregulatory mechanisms as well), but it’s kind of a double-edged sword.  The blood traveling at such a shallow depth past the guttural pouches also makes that blood supply susceptible to damage.  It’s not uncommon for a fungal infection to set up housekeeping in the guttural pouches (it’s called guttural pouch mycosis), and the fungus causes erosion and damage to the walls of the pouches, including the carotid artery.  If the fungal erosion causes enough damage to the arterial wall, it can give way entirely and because the carotid is at such high pressure and receives such a large amount of the cardiac output from the heart, it can cause catastrophic bleeding.


Does that make sense?


Susan Garlinghouse, DVM


From: D'Arcy Demianoff-Thompson [mailto:cest.mon.virage@xxxxxxxxx]
Sent: Sunday, February 17, 2008 5:29 PM
To: heidi@xxxxxxxxxxxxxxx
Cc: suendavid@xxxxxxx; Linda Winkel; ridecamp@xxxxxxxxxxxxx
Subject: Re: [RC] EIPH bleeder???


Oh, Heidi, I am soo sorry to hear about your mare.  Maybe Sue can answer this question about the erosion of the gutteral pouch.  Is this caused by stomach ulcers.  Or are we talking the same thing with a scientific name?

<, and otherwise the picture of health.  Came out one morning and found her dead, bled out through the nose, and it was an erosion in a gutteral pouch...  So yes, ditto what Susan said--get the horse scoped, and see if you can find out where the blood is coming from.


RE: [RC] EIPH bleeder???, heidi
Re: [RC] [RC] EIPH bleeder???, D'Arcy Demianoff-Thompson