Ask the Vet – What is Cushing’s Disease in horses?


SARAH: “What is Cushing’s,
and what is it caused by? What can I do to manage it?” DR LYDIA GRAY: So you’ll
help me make sure you answer each of those questions. So the first one is– SARAH: I can keep
track of the questions. I will not be doing
the answering. DR LYDIA GRAY:
What is Cushing’s? So the other name for it, the
name that your veterinarian might use is pituitary pars
intermedia dysfunction, or PPID. So here we go with the acronyms. And it’s a collection
of clinical signs that are associated with
an endocrine dysfunction. So what happens is
your pituitary gland– and there’s three parts. That’s why it’s narrowed
down to the middle part, pars intermedia– is under negative
inhibition, so it’s being kept in check by another
section of the brain called the hypothalamus. And the hypothalamus,
one of its many jobs is to send over a signal,
a neurotransmitter, dopamine specifically, to the
pituitary and say, “Calm down. Keep calm and carry on. Just chill.” And then, everything’s fine. But as age, oxidative
stress, happens to horses– so this is a senior
horse disease– then, the hypothalamus doesn’t
do as good a job sending over that signal and the
pituitary is unchecked and it becomes enlarged and
overactive, dysfunction. And so then, it
releases some hormones. ACTH is probably the
best known of those. And then, we have this
collection of clinical signs. And so it might be a
long and curly hair coat, which we call hypertrichosis. It could be weight loss,
specifically muscle loss. And here, I’m thinking over the
top line and the bottom line, or the underline, the belly. Increased susceptibility
to infections, so the immune system is dampened. Laminitis is a problem. They might urinate more
frequently and then drink more. So it is truly a cluster or
collection of clinical signs. And together, you begin to
notice things not quite right with your horse, even
behavior, attitude changes. And you talk to
your veterinarian. And then, they
come out and test. SARAH: So we’ve got what is
it, what is it caused by. What can I do to manage it? DR LYDIA GRAY: So well, I guess
we can go on with your vet. So your veterinarian comes
out and diagnoses it. And this is a pretty
simple test now. Now, it’s just an ACTH test. And it’s a one time blood draw. So it’s pretty simple. It used to be an
overnight and fast and you give something
and that’s all done. So once your veterinarian
has a number, there is an
FDA-approved medication for it called Prascend, which
the active ingredient is pergolide. And so you give
that and you retest. And you look for the clinical
signs, the long curly hair coat. These horses, they don’t
shed out in the spring. That’s sort of the
classic, what you see. SARAH: So if these aren’t
working, might have a problem. DR LYDIA GRAY: Call your vet. That’s right. So if the blood work comes
back, like in 30 days, better and the horse
begins to shed out, then you’re on the right track. And if not, then, maybe
test the blood again. And maybe the medication
needs changed. So that’s the
medication side of it. There are some
supplements, specifically targeting the muscle loss. So you can add back
in extra amino acids, lysine, methionine,
and threonine to help build up that top line. You can add in some
antioxidants, because we know the hypothalamus
is not working properly, because of
oxidant-induced injury. So get those going. Some omega-3 fatty
acids to help balance the inflammatory and
anti-inflammatory side. And there are some other herbs. Adaptogens would be great to
support the immune system. Feeding, you don’t know
what you’ll need to feed or how you’ll need to feed,
unless your veterinarian does the test for Cushing’s, as
well as a second test, the test for insulin resistance, because
you can have Cushing’s alone. And that’s pretty manageable. You just feed to the
body condition score that the horse should be at. And you feed to their
teeth and whatever issues they might have. But if they also have
insulin resistance diagnosed with the oral sugar
test, then you need to reduce the
sugars and starches. So it’s things like
soaking the hay or having them wear
a muzzle or not feeding early or at least
reducing grain and watching the treats that you give. So no longer a
bag of peppermints or a bag of carrots. I know people that do that. But you don’t have
to do those things, unless your horse has insulin
resistance as well as the PPID. SARAH: You talked a couple
of times about a word that I think we’re
pretty familiar with here at SmartPak, or a phrase. But I think some of our fans
might be less familiar with. And it brings me almost
back to the same grade that I was in when I was
learning about photosynthesis, oxidation or oxidative stress. And so the way that I think
most people might be familiar with it is, if you
think of oxidizing, you might think
of rust on metal. And so, hopefully, unless we’re
talking about the horse shoes, a horse shouldn’t be
experiencing rust. So what kind of oxidative
stress are horses exposed to? And how does that happen? DR LYDIA GRAY: So think of
normal things like sunlight, with the ozone layer
and all of that and chemicals and just the
environment and life itself. I mean, exercise induces
injury oxidative stress. And so it’s when free
radicals are generated and you need antioxidants
in your body to capture them as they are generated. So Vitamin E is an
excellent antioxidant. Vitamin C, Vitamin A,
there’s some other ones. I like alpha lipoic
acid, because it’s both fat and water soluble. So it can go everywhere and
gather up these harmful agents that are released. So if you have antioxidants
on board through the diet– selenium is one. It partners with
Vitamin E– then, you’re in better shape
than if your horse is dealing with this oxidative
stress on his own. SARAH: That all horses are
exposed to all the time. DR LYDIA GRAY: All the time. Yeah. So if there’s more
oxidative stress going on, then they’re going to burn
through their normal amount of antioxidants they have. And so it helps to have more.


8 Responses

  1. Molly McCarthy

    May 20, 2017 4:25 pm

    Can you guys do I video on board on with horses when they're in their stalls and paddocks how to get them to stop Cribbing


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