DAN: "What causes swayback, and how do you prevent it?"
DR LYDIA GRAY: Well, there's no answer
to either of those questions.
So we're done.
DAN: That's the end of the episode.
DR LYDIA GRAY: So sway back would be the colloquial term,
and the term that the veterinarian would use
is lordosis.
And lordosis means an inward curve of the spine or an arch,
versus a kyphosis is an outward curve or a hunch,
and then scoliosis is a sideways or lateral curve.
They all have names.
It's hard to tell what she's thinking of.
There's early onset lordosis, like in a young horse,
and then there's the old-age associated or late-term.
DAN: Which most people feel is common to see.
DR LYDIA GRAY: As the horse ages,
the soft tissues that hold the spine rigid begins to sink.
Those tissues become lax or loose,
and the muscles in the belly and the back sort of become
less strong, and the whole thing sort of sags over time.
DAN: OK, so the muscles in the abdomen
is not strong enough to also keep the back up,
plus the back muscles are--
DR LYDIA GRAY: Ligaments and the tendons,
they're sort of loosening, and softening,
and not doing-- they're not as structurally sound.
But it's different in the young horse.
There's a theory that the young horse--
there's a deformity in the vertebrae themselves.
Because if you're 18 months or two years old,
and you have not a gentle sag like an older horse,
but a pretty extreme--
that looks different, and you would
suspect the bony shapes to be different,
and radiographically, it's been shown they are.
DAN: So there's something more severe going on.
DR LYDIA GRAY: Yes, but interestingly enough,
horses are one of the only species that
can have a significant lordosis and not be affected.
They can still have a normal, long, healthy, productive life.
DAN: But could you ride them?
DR LYDIA GRAY: Yes.
DAN: Interesting.
DR LYDIA GRAY: Yeah.
It does not seem to affect their performance,
their way of going, they could still be a brood mare.
DAN: We've all seen that horse who
looks a little dipped in the back, where it's
a nice little seat for you to sit in,
but I always thought there might be some discomfort that
goes along with that.
DR LYDIA GRAY: It doesn't appear to be,
just talking about the back issue.
Now, when you put a saddle on, then you could create an issue
because if you've got a back that dips,
now you've got the potential to create bridging,
where the front of the saddle and the back of the saddle
touch, but the middle doesn't.
DAN: OK, so now you're hitting weird pressure points.
DR LYDIA GRAY: Yeah.
So now you have to be really, really careful
that your saddle fits if you're going to have-- if you're
going to continue to ride it.
A horse that ages into it or a horse that just has it from the
get go.
DAN: Well, there are a lot of saddle pads now
that are designed to kind of help
with some of that bridging for horses
who do have some sway back to kind of help that
out a little bit.
DR LYDIA GRAY: Yeah, and I would probably
engage in services of a saddle fitter to make sure.
A couple more things I wanted to say
was that the reason this is not studied a lot--
and so causes and prevention and correcting--
is because only about 1% the general horse population
has this, and it's just not enough for the money
to be there to research it.
About 7%, though, of American Saddlebreds have this.
DAN: I was going to say.
DR LYDIA GRAY: I'm sure you were thinking that.
It can happen to any horse, but Saddlebreds,
they are now confidently saying there
is a heritable or genetic component to it.
The specific gene has not been identified,
but they're really close.
They do know that the gene is recessive, not dominant, which
means you have to have two copies of it to show it.
So the sire and the dam must both have a copy,
if you remember your Mendelian genetics.
DAN: I remember my little Punnet square.
I knew it would come in handy one day.
DR LYDIA GRAY: So it's seen more often in Saddlebreds,
and when it comes to the causes--
for Saddlebreds, at least-- there is a genetic component.
Preventing it, other than not breeding
two horses that have it, that's the only way
you can prevent it.
And then once it begins, there's not really
anything you can do about it.
DAN: Well, I was just going to say
there's not any sort of exercises
you could do to help support the abs and make sure
the horse is engaging?
DR LYDIA GRAY: Maybe for the old age onset version of it,
you could encourage them to have that lift
in the back, and the roundness, and you
do exercise that support--
the abdominal muscles, but I think
you're just prolonging it or extending
their normal lifespan.
Or slowing the progression down.
DAN: It's not going to cure it.
DR LYDIA GRAY: You're just slowing things down.
Slowing the inevitable down.