DAN: "Are horses similarly prone to depression like humans?
If so, what are some symptoms and ways to treat it?"
DR LYDIA GRAY: Well, this may have been the most fascinating
question we've ever gotten.
DAN: I loved it.
DR LYDIA GRAY: Because I've actually never considered
whether horses get depressed.
And it's not a term that we learn about
in veterinary medicine.
It's more of a human thing, I thought,
until I looked it up for this, and it turns out
that there is a growing body of research
around equine depression.
But I want to back up a little bit.
So when I first read this, I thought, "Oh sure,
like a horse leaves the herd, and his friend is sad."
Well, that's more separation anxiety.
And then maybe a horse dies, and his buddy
is there and knows it happened, but that's more sadness, grief.
So then I thought, well, how is-- then I thought,
how is sadness different from depression?
DAN: Exactly.
DR LYDIA GRAY: So I had to look that up,
and it turns out that-- and this is a little blend of human
and animal, but sadness is a temporary, normal emotional
experience that we all do, and it's about one thing.
It's about some thing.
Like that my horse friend died, or--
DAN: Sad over one instance that happened.
DR LYDIA GRAY: Exactly, an issue.
And depression is an abnormal mental state
where you're sad about everything,
and it affects your thinking and your behavior
and your perceptions, and it's just widespread,
and you can't do anything about it.
One of the core clinical features of depression--
this is a word I did not-- this is not a veterinary word.
It's a human medical word, but now we're
using it on horses because we're studying depression.
It's called anhedonia.
DAN: I love when you say a good, big word like that.
DR LYDIA GRAY: I know, and I'm going
to read the definitions just to make sure I get it right
because now I'm treading a little bit
into the human medical field, but it's
the reduced or inability--
lack of the ability--
to experience pleasure in normally
pleasurable activities.
So for horses, maybe taking a treat-- eating a treat.
They don't care anymore.
Another way to define it is if you've
lost interest in activities that you used to enjoy.
Maybe pasture was your thing, and the gate would open,
and you were right there, and you're like nah.
DAN: Now they're just kind of standing there.
DR LYDIA GRAY: Yeah.
There is some really interesting research
that just happened in France.
They validated this person's question
that horses do experience something
akin to depression in humans.
And first, they defined a term, withdrawn horses.
So instead of saying a depressed horse,
they're calling it withdrawn, is their terminology,
and it could be a translation thing.
I don't know.
But they described them as having
long bouts of immobility, an unusual posture with backward
facing ears, a flattened neck, and the head fixed.
Wide open eyes with unusually long interval in blinking.
So like a fixed stare.
DAN: So just like glossed over almost.
DR LYDIA GRAY: Yeah, exactly.
You've got it.
And then standing in the stall with the head towards the wall.
Turned away.
And so what they're doing is they have tuned out
from their surroundings.
They've checked out or switched off,
and they think-- the theory is it's
in response to chronic or long term physical or mental stress.
So their study was--
DAN: So it's almost like a survival mechanism.
DR LYDIA GRAY: A coping-- yeah.
So the study was they measured how
the control group of normal horses and the withdrawn horses
reacted to five sounds.
The five sounds were a baboon call.
They'd never heard.
These are novel noises.
A goose call, a whale call, an unfamiliar horse.
So a horse whinnying they've never
heard before, and then a piano.
DAN: If my horse ever heard a baboon call,
he would be on the other side of the arena.
DR LYDIA GRAY: Well, that's the normal horse.
90% of the normal horses-- they videotaped them--
had a reaction to these calls, and the interesting thing was,
over time-- they did this each day--
they habituated.
They got used to it.
DAN: So being exposed to it more frequently,
they now weren't so concerned about it.
DR LYDIA GRAY: And that was normal.
The withdrawn horses or the abnormal ones, half of them
had no response to the noise.
DAN: Wow.
Nothing at all?
DR LYDIA GRAY: Just didn't care.
DAN: Wow.
DR LYDIA GRAY: Just didn't care.
They were experiencing anhedonia.
And over time, their reaction didn't change.
DAN: Really?
DR LYDIA GRAY: Didn't care, didn't care,
didn't care everyday of the experiment.
DAN: Oh, that's so sad, though.
DR LYDIA GRAY: I know.
And so what they're saying is if you notice a horse that
is like this, you need to look into it-- you and your vet--
because there's a problem.
Pain and discomfort is probably the most common reason
for horses to check out or withdraw,
and so you need to evaluate is there a soundness issue?
Is there a pain in some other part of the body?
DAN: They're just so uncomfortable that--
DR LYDIA GRAY: Their way of coping
is to just check out so they don't feel it.
The other thing is evaluate their living conditions.
So their social life, their stabling, their turnout.
Those kind of things.
Because especially if other horses in that same barn
are experiencing either the withdrawness or aggression
or stereotypical behaviors like cribbing or weaving
or stall walking or those, that's
a sign that the horse is experiencing stress.
So it needs to be looked into.
DAN: So they may have to look at what's our entire management
program.
DR LYDIA GRAY: Exactly.
DAN: And what are the things we could change?
DR LYDIA GRAY: Exactly.
So if there's one horse doing it,
it's probably something that just that horse
is experiencing--
either pain, discomfort, or some emotional problem.
Or if it's a lot of horses, then it's management.
DAN: Are there simple things you could possibly
do like putting them in a stall that's maybe--
so they can see other horses or see if they
can have a turnout buddy?
DR LYDIA GRAY: I think you have to--
I think observation is key, and documenting
that horse's experience.
So what is it?
Is it that the stall--
you know how some stalls are solid walls
and don't have any way to see?
Maybe he can't see another horse.
Maybe the tack stall is right across from him,
so his front is not even a horse, and his sides are solid.
It could be anything.
So your powers of observation are your friend here.
DAN: And let's be careful, though,
because like let's observe, but don't necessarily
go up to your horse with a baboon noise right off the bat.
DR LYDIA GRAY: Don't recreate the study.
Just know what's normal for your horse,
and if they begin to behave differently,
then pay attention.
DAN: Absolutely.
DR LYDIA GRAY: Yeah, that's all we're saying.
DAN: That's so interesting, though.
It's nice to see that there's lots
of studies going on about that.
And some things, I think, that we just
take as normal behavior for that horse
could actually be a deeper issue.
DR LYDIA GRAY: And that it's important that somebody knows
that horse's--
how he acts normally, and speaks up when he doesn't.
DAN: Absolutely.