Re: Tying-Up

[Kim <kim@redhorsetech.com>]

> > Is there any genetic component to a horse tying-up?  

> The latest issue of Equus also had an article on the topic
> that discussed TB - and I think QH - that also said there
> was a genetic element in this.

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I haven't read the Equus article (please forgive me if this is old news
to some), but equine polysaccharide storage myopathy (EPSM) may be
genetic, and can produce symptoms of recurrent exertional rhabdomyolysis
(multiple Tying-Up episodes) as well as other symptoms (weakness, muscle
atrophy, etc.).  The few research papers on this condition seem to
suggest that it may be a recessive genetic trait... something to
consider regarding the horse the RideCamper was thinking about
purchasing.

The breeds are not limited to QH.  EPSM has been also found in draft
breeds, Thoroughbreds (and crossbreds), Morgans, Arabians (and
crossbreds), Standardbreds, Warmbloods, pony breeds, Minature Horses, as
well as others.  It may seem to be more prevalent in QH breeds because
of the increased number of Type II muscle fibers (fast twitch low
oxidative) in this particular breed... the fibers used for sprinting and
"power work", if you'd like to think of it that way.  But, all breeds
have at least some Type II fibers, so there's no way of just selecting a
breed to avoid this condition.  

With ESPM, too many complex polysaccarides and glycogen accumulate in
these fast twitch fibers, which is why some researchers are trying new
rations using low carbohydrate (low grain) / high fat for fufilling the
energy needs. The new ration seems to help reduce or even might
eliminate the tying-up episodes in the horses studied, but, personally,
if I was looking for an endurance prospect, I would probably want to
look around for another horse.  Some horses can be managed well with
this condition, but you are gambling unless you know that a diet change
is all that is needed to treat this condition.  

Tying-up symptoms can also be non-EPSM related, maybe even just a simple
ration imbalance if the horse is working hard (low vit E or selenium,
hypocalcemia, days off on full grain ration, and so on)... it's tough
call.

Now that life has become more complex :->... hope it helps some.


Kim (and Lee. A horse's life is never complex)


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