From:
Sukie Crandall
Date: 2005-10-19 14:14:42 UTC
Subject: [ferrethealth] I have a question about esophageal pain nerves and about MegaE
To: ferrethealth@smartgroups.com, ferret-list@cunyvm.cuny.edu
Does anyone know about pain nerves in the esophagus?
I am wondering if the throats of members of carnivora are less
sensitive to pain than those of other animals, and if this might be
one reason that something like MegaE takes off as well as it does
without early symptoms in them. Looking at Megaesophagus in the
humans I notice that the symptoms appear to show up much earlier with
painful swallowing and dysphagia. In looking it up humans' causes
appear to be neurological diseases like Chagas and some other neural
pathologies, or due repeated stretching at areas with preexisting
damage to the esophagus, and POSSIBLY rarely as a congenital
malformation. (There are known dog breeds with a congenital genetic
aspects but what I have read so far does not mention that in relation
to anything else and says that it is postulated but debatable. Two
special lab strains of rodents get it spontaneously.)
http://www.critterchat.net/mega.htm#ref1
which is a comfy read in relation to dogs writes
>The increased incidence in these breeds is speculated to involve
delayed maturation of >the nerve plexus innervating the esophagus and
lower esophageal sphincter. These >dogs often gradually acquire
normal esophageal peristalsis and control of the lower >esophageal
sphincter over a period of a few weeks to two months2. There is also
a >predisposition in certain canine breeds to develop megaesophagus
secondary to patent >right aortic arch2.
and
>In humans, the majority of megaesophagus cases are secondary to
achalasia. >[Achalasia is the inability of a hollow organ to
relax.] People diagnosed with achalasia->induced megaesophagus range
in age from 25 to 60 years1. In achalasia-induced >megaesophagus,
there is an insufficient or uncoordinated relaxation of the lower
>esophageal sphincter and decreased peristalsis in the lower
esophagus. The achalasia >can be due either to muscular or neurologic
abnormalities1. The neural component is >considered to be more
commonly involved1. Other less common causes of >megaesophagus in
people include systemic disease, anatomic anomalies, myasthenia
>gravis, stroke, amyloidosis, hypothyroidism, vagal afferent
dysfunction, Trypanosoma >cruzi infections, and foreign body
obstruction of the esophagus
(BTW, aspiration pneumonia appears to be common in any species with
this disorder.)
The reason I was wondering is because I had to have some tongue
surgery yesterday -- larger but far less painful and quicker starting
to heal than I was told to expect so, yes, you can joke about it with
me off-line should you so desire -- but the half dozen stitches
rapidly tore out, especially with swallowing, and I found that
swallowing new stitches is actually quite painful for the throat --
at least for my throat (and I am someone whose med file includes
"under reports pain" in bold red magic marker).
Yet, ferrets, dogs, and cats and their wild relatives regularly
swallow far scratchier things without complaint and sometimes with
relish, and some love to try to eat string, fabric, or even dental
floss. They also bolt food more, and seem to think little of
bringing it up for more chewing when needed.
So, I am wondering if perhaps members of Carnivora might at times
repeatedly injure the esophagus without feeling it much -- setting
the stage, and if they perhaps usually don't feel the beginnings of
MegaE from repeated injury because they might have a reduction in
pain perception in the esophagus -- basically that the sorts of
things they are inclined to eat might be what set them up for the
condition, but do note these essential points:
>Canines and rodents have striated muscle throughout the length of
the esophagus, >while in humans the proximal esophagus has striated
muscle which gradually changes >to smooth muscle in the lower
esophagus5,6. In addition, a reproducible animal model >of achalasia-
induced megaesophagus has not been produced.
>...Some forms of megaesophagus respond to isosorbide dinitrate and
calcium channel >blockers treatment, physically by pneumatic
dilatation, or by surgical myotomy of the >lower esophageal
sphincter. In most cases, if there is an underlying degenerative
>neural lesion or other physiologic abnormality in the esophagus,
the treatment is >primarily for temporary amelioration of symptoms1.
And, yes, I realize that I am just hypothesizing here, so it is
grain of salt time, just as with any unproven thing that is
postulated by anyone anytime.
-- Sukie (not a vet)
Ferret Health List co-moderator
http://www.smartgroups.com/groups/ferrethealth
FHL Archives fan
http://ferrethealth.org/archive/
replacing
http://fhl.sonic-weasel.org
International Ferret Congress advisor
http://www.ferretcongress.org
====================================================================<<<
Whatever you Wanadoo, click below:
http://ads.smartgroups.com/adclick/CID=000000b7c79a99a500000000
====================================================================>>>
--
If you want to share pictures, use the calendar, or start a vote
visit http://www.smartgroups.com/groups/ferrethealth
To leave the group, email: ferrethealth-unsubscribe@smartgroups.com
Report abuse http://www.smartgroups.com/text/abusereport.cfm?gid%3D1423922&mid%3D15738