Re: [RC] colic at rides--LONG--part 2 - Heidi Smith
Part 2:
One of the least
deadly sorts of colic is usually gas colic (depending on the severity of
it). This can be a gray area--you can get a gas colic with a change in
feed (so that isn't overriding, but could still be considered a part of horse
management), but you can also alter the gut flora by stress, changes in
temperature, pH, etc. So overriding can contribute to a gas
colic.
But let's look at
twists, intussusceptions, and those sorts of things. In order for a horse
to twist a bowel, there generally has to be a lack of tone to the gut. And
what happens when you override a horse? You dehydrate him. You empty
his gut of food. And you alter his electrolyte balances--one of the
most problematic here being calcium. If the muscle cells in the
gut become hypocalcemic, the smooth muscle can no longer contract
properly. The bowel becomes flacid and floppy, and a twist can occur with
the slightest provocation. So yes, these sorts of colics
post-ride are often directly due to pushing the horse past his metabolic
limits. But because there is an element of bad luck in these situations as
well, you may push him past the wall 10 times with no "problems" and get caught
the 11th time you do it. You may have him standing there in the danger
zone without realizing it, but you have, indeed, "ridden him to death" in a
sense, because if you had not overridden him, his gut would not
twist.
The stomach
ruptures would fall into the same category. Fluid is generally transported
across a healthy stomach lining so quickly as to seem instantaneous.
A horse's stomach only holds two gallons--and yet, if he is ok he can slug down
5 gallons of water and hardly come up for air without the slightest
discomfort. If drinking is making him uncomfortable, that is a big red
flag--the cellular transport mechanism in the stomach is failing! Reasons
for this go back to the overriding issues--the cells are dehydrated, the cells
have improper electrolyte balance, etc. I'd suspect that the ones that
rupture more often than not also have ulcer damage--but again, one should be
able to have some idea on post-mortem if the ulceration was sufficiently bad for
rupture to occur at normal pressures or if the stomach was further compromised
so that it could not empty properly.
Another situation
that can lead to stomach rupture is anterior enteritis. I do think there
are some management issues that can contribute to this. But there are also
horses that are just more prone to it with even a mild variation in what is
happening in their gut. What happens with anterior enteritis is that the
transport of water across the lining gets so screwed up that it goes the other
direction, and fluids are pumped INTO the stomach and upper small intestine
(where they run back into the stomach) instead of OUT of it. Horses with
anterior enteritis can be on literally gallons of IV fluid, and they will reflux
sometimes literally gallons of fluid back out of the stomach. I've had to
deal with a few of these in the field, and they are nasty--they're the sort of
thing you want to get to a hospital setting ASAP. Again, I think there can
be other management issues here--but those aside, yes, these horses are
suffering from being overridden in some
cases.
