Ridecamp: Re: [RC] what's a crash (was Vetting procedures)

> What does "crash" mean exactly? Is there a common crash to an endurance
> horse...is it cardiac arrest?  Do horses
> "faint?" Is it severe dehydration where the systems shut down?

There's a group of symptoms collectively called exhausted horse syndrome,
which is the result of dehydration, electrolyte imbalances, secondary colic
symptoms, high body temps, etc.  When a ride vet does the metabolic,
non-lameness portion of a vet check, he/she is checking for signs of
impending exhausted horse syndrome.  If a horse does get to a critical stage
of EHS, then there are a lot of body systems that are concurrently being
adversely affected.  The most critical problem is electrolyte depletions and
imbalance, because when those aren't right, you get all kinds of muscle
problems from cramping to collapse, cardiac irregularities (including
arrest), deficits in neural function (everything from a loss of thirst
response to thumps to convulsions) and changes in acid-base balance (too
complex to explain, but Bad Juju).  Dehydration causes decreased oxygen
perfusion to tissues and thus poor gut motility (and impending colic),
increased muscle damage from overexertion and problems with acid-base and
electrolytes again.  The dehydration and muscle damage puts a lot more
strain on the kidneys and if/when they get presented with a deluge of waste
products from damaged cells, can be overwhelmed and irreparably damaged.
High body heat in general slows down and impedes all of the body systems and
at worst, can contribute to disseminated intravascular coagulation, where
the clotting and inflammatory mechanisms in the body start to cascade and
result in the formation of blood clots in the circulation which then can
clog up circulation to the brain, heart, lungs and so on) and also the
destruction of blood cells.

So all of this can happen depending on the severity of the crash, but the
major component that has to be treated is just plain old shock.  Loss of
blood pressure, loss of blood circulation to the organs and death.  Shock is
the major reason why the vets will start running in IV fluids pretty much
wide open, along with electrolytes and depending on the situation, DMSO (an
inflammatory and free radical scavenger), anti-inflammatories/analgesics
like banamine or tranquilizers like acepromazine (both of which can make the
problem alot worse if not used correctly, so don't try treating this on your
own).

Obviously, not every horse that gets a metabolic pull is on this kind of
edge, but when the ride vet looks the horse over, this is a big part of what
they're trying to prevent.  I think it's important for riders to realize
that there's a point at which try as they might, the cascade of events can't
be stopped or repaired.  Sorry if this was more information than you really
needed, but I think every rider should realize the stakes they're playing
with when they override a horse, or aren't absolutely upfront with the vet
when the horse isn't doing right.  No completion on earth is worth this, eh?

Susan G



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