June 13, 2025 • 21 mins
Dr. Roy Madigan joins us to uncover the hidden danger of Chagas disease, a parasitic infection transmitted by "kissing bugs" that's far more prevalent than most veterinarians realize.
Contrary to outdated beliefs that Chagas is a "third world disease," this silent killer affects up to 18% of dogs across the southern United States, with millions of cases going undiagnosed. Dr. Madigan shares how his journey began with one fateful case named Max, whose unexplained death led to a 25-year quest to understand this misunderstood condition. What he discovered changes everything we thought we knew about cardiac disease in dogs.
The most alarming revelation? Heart rate variability analysis shows that dogs with Chagas disease develop serious autonomic nervous system dysfunction long before showing any symptoms. This explains the devastating phenomenon of sudden death in apparently healthy dogs—a tragedy Dr. Madigan has witnessed countless times. Through sophisticated monitoring techniques, veterinarians can now detect these dangerous irregularities early, potentially saving lives.
Perhaps most concerning is the One Health implication. Dogs serve as sentinels for human infection, with Dr. Madigan noting that several dog owners have tested positive for Chagas only after their pets were diagnosed. The disease doesn't discriminate based on neighborhood or housing quality—these bugs readily infiltrate modern homes regardless of socioeconomic factors.
For veterinarians, the message is clear: implement thorough cardiac assessments and consider Chagas when arrhythmias are detected. For pet owners, especially those in the southern states or who've adopted dogs from these regions, ask your veterinarian about testing. Your vigilance might save not only your dog's life but potentially your family's health as well. Listen now to understand the heartbeat irregularities that could be your first warning sign of this emerging threat.
JAVMA article: https://doi.org/10.2460/javma.24.12.0773
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Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Speaker 1 (00:01):
This is Veterinary Vertex, a podcast of the AVMA
Journals.
In this episode we chat aboutheart rate variability
derangements in dogs with Chagasdisease with Roy Madigan.
Speaker 2 (00:13):
Welcome listeners.
I'm Editor-in-Chief LisaFortier, and I'm joined by
Associate Editor Sarah WrightRoy.
Thank you so much for takingtime out of your busy schedule
to be with us here today.
Speaker 3 (00:23):
Thank you, Lisa and Sarah.
It's a pleasure to be here.
Speaker 1 (00:26):
All right, let's dive right in.
So, roy, your JABMA articlediscusses how heart rate
variability analysis may enhanceearly detection and management
of Chagas disease, which is anemerging One Health issue, by
addressing underdiagnosedautonomic and cardiac
dysfunction in dogs.
Please share with our listenersthe background on this article.
Speaker 3 (00:46):
Thanks, sarah.
Yeah, so for those listenersthat don't know much about
Chagas disease, or if you'relike me and you kind of slept
through that section inparasitology, just a brief
background Chagas disease is aparasitic disease.
Okay, it's caused by aprotozoal organism called
Chapanosoma cruzii.
So you know, not a virus, not abacteria, but a little tiny,
little microscopic bug similarto toxoplasma leishmania, if
(01:08):
you're over in Europe, and soit's.
It's pretty widespread as faras Southern United States.
The Southern 26 states,including Texas, which is where
I practice, is just inundatedwith it, and it's mainly because
we have the vector, and thatvector is called the kissing bug
or the triadamine bug.
So it's a little bit bigger orprobably in similar in size,
(01:30):
depending on where you are, to acockroach, but it's like a
giant mosquito it crawls, itflies and it takes blood meals,
and so wherever we find thatvector, you know we're going to
find the disease.
Generally, we're taught inveterinary school that it's a
disease of third world countries, and so you know, central
America, south America, but wehave quite a bit of it.
Essentially, what happens isthe parasite is in the hindgut
(01:53):
of this kissing bug, so it'sactually not transmitted through
the bite of the bug likeheartworm disease, but it's
spread through the feces.
So when this kissing bug takesa blood meal from its host,
whatever mammal it decides to do, it'll actually defecate, and
in that feces the parasite istransmitted into the bite wound
and then gets into circulation.
That's the classic transmission.
(02:15):
Other methods are a little bitmore effective in our companion
animals because they eateverything.
If you have a dog, you know howit goes.
They eat everything smallerthan themselves, especially when
these bugs have a nice crunchycenter with blood in it right.
So major reinforcement there.
And so these kissing bugs arecommonly ingested through the
oral route.
Other methods of transmissioninclude vertical transmission,
(02:38):
so from the bitch to the babieswe also had through blood
transfusions.
Obviously that's much lesscommon than on the human side,
and we also have carrioningestion, so eating stuff
they're not supposed to, whichI'm sure your dog's never done
before, and so those are prettycommon methods of transmission.
The parasite is very, veryeffective at getting into all
tissues.
(02:58):
So one common misconceptionwith Chagas disease is that it
only goes to the heart.
We tend to look at the heart alot because any amount of
myocarditis is bad, but itcauses inflammation in any
tissue that it goes to includingthe heart for myocarditis, and
so the disease that it causes ispretty simple.
(03:20):
Okay, it generally causes aprogressive chronic myocarditis.
Okay, if you think of it thatway, there's kind of like three
pillars that it operates in,okay, so by presence of the
parasite we cause tissue damage,so when those cells get
ruptured they die, right,regardless if it's in the liver,
the brain, the heart.
The second thing that it does isit causes inflammation, or what
(03:41):
we call the host immuneresponse, and so the body's
response to the disease or theparasite itself causes damage.
And then the last thing that itdoes is it causes some
microvascular disturbances, sotiny little microclots and all
the wonderful things that thosedo in tissues, okay, but the end
result, when we're talkingabout the heart, is generally
systolic dysfunction, eventuallyelectrical disturbances, which
(04:05):
is huge, okay, and then you know, over time we can get these
autonomic disruptions.
So our paper really focused onthese autonomic disruptions that
happen.
So more of a nervous systemeffect.
It really hasn't been looked atin dogs, and so that's what
kind of drove us to do thispaper and gather this data,
(04:27):
because we wanted to see, youknow, we know it happens in
humans, but does it happen indogs, and so it's very, very fun
to explore that.
Speaker 1 (04:36):
Yeah, thanks.
That was a great review.
Appreciate that.
So what are some of theimportant take-home messages
from this article?
Speaker 3 (04:43):
Yeah, I think the biggest thing that I'd like to
share with veterinarians youknow we obviously in private
practice don't do too manyHolter monitors, right, but
certainly everybody has accessto EKGs, ECGs, and hopefully
most of you are using those now.
You know, back when I graduateda long time ago, not too many
of us had ECGs for surgicalmonitoring, but that can be your
(05:04):
most reliable indicator ofearly detection for Chagas, you
know.
You know, classically thisdisease is diagnosed through
serology.
So we're going to be checkingthe body's response to the
parasites.
We're not looking for directparasites, necessarily.
We're looking for the antibodyresponse, right.
But the biggest red flag, atleast in our hospital, probably
a third of the cases that wediagnose are under anesthesia,
(05:26):
with arrhythmias, and so there'sa lot of papers out there that
look at arrhythmias.
You know the types, thefrequencies, all that.
But the biggest surprise for mewith this was that heart rate
variability analysis, which isjust a fancy term and a set of
tools that measure autonomicfunction in the heart, so
(05:49):
sympathetic versusparasympathetic, and there's
these distinct markers that havea lot of abbreviations.
There's a lot of math involvedwith it, but essentially, at the
end of the day, these justreflect the function of that
autonomic nervous system.
Okay.
So the the big take home is,you know, let's, let's kind of
(06:09):
expand our knowledge when we'relooking at these Holter reports,
when we're looking at HRVanalysis, instead of just
glossing over it and ignoring it.
You know, kind of really give ussome thought there.
If I see a derangement, if, ifI live in an area that's endemic
for Chagas disease again, it'slike if you're South of Oregon
and south of Pennsylvania,you're in that region, Okay.
Or if you have a dog with atravel history, maybe they
adopted the dog from the south,you know, maybe maybe you're in
(06:32):
like I've got a dog in Singaporeright now that we're treating.
I mean, how did that happen?
Right, so people travel aroundthe world and so if I'm, if I
have an abnormality in myphysical exam, I'm doing a
Holter monitor, or maybe thecardiologist is, you know, give
some extra thought to that andconsider maybe I'm dealing with
Chagas and I need to do a testfor that.
Speaker 2 (06:51):
Yeah, fascinating.
We recently did a podcast onRocky Mountain Spotted Fever and
how it's creeping its way intoplaces that it never was before
either, and I think that podcastand your article and this
podcast also really highlighthow important the role of the
veterinarian is in these OneHealth situations, to recognize
(07:14):
it in the animals as well as inpeople.
Speaker 3 (07:17):
Yeah, lisa, you bring up a fantastic point.
You know, dogs are sentinelsfor this disease across the
world.
We know that.
So when we look at dogs withChagas disease, it's always
associated with a higher risk ofinfection in their human
counterparts, right, and youknow, let's face it.
You know, when we were growingup, dogs lived outside.
Now they live in our bedroom,right, and so they bring in all
(07:40):
kind of fun creatures, includingkissing bugs.
You know these little vectorsand we see them, and you know
our clients see them in theirbedrooms, you know, and they
don't live in thatched huts,right, and so I don't know about
you guys, but we wereincorrectly taught in vet school
, and still are to this day,that this is a disease of third
world countries.
This is not.
You know, you can live in agated community and that gate
(08:02):
won't stop these kissing bugs,right, and so we've got to be
aware of that.
So the one health implicationsare huge.
Years of, you know, diagnosingand treating this disease.
I've only and we're talkingthousands of dogs, okay, but
I've only had six people thattested positive.
However, they would not havegotten tested if their dogs
(08:25):
didn't have it, and so hopefully, you know, their physicians
were able to intervene and helpthese people and, as far as I
know, they're all alive still.
So.
But dogs, dogs can help, youknow, dogs can help us.
Dogs can help us diagnose othermammals in the pack.
We've had a lot of cats, we'vehad a lot of horses and again
they would have gone undiagnosed.
In fact, in my own pack here Ihave three dogs.
(08:47):
I know that's weird, aveterinarian with only three
dogs.
One of our dogs, our goldenretriever, during her surgical
procedure at two and a half, wenoticed an arrhythmia that
triggered us to test.
She almost died.
She was in VTAC on the table.
That's not fun, but wediagnosed Chagas disease on her
(09:07):
and that triggered me to testthe other dogs and they were
also positive.
So you know, early detection iskey.
You know, and I think thisparticular set of indices, this
heart rate variability, lookingfor arrhythmias on your EKG or
Holter, is huge and it's goingto help us diagnose more
patients for sure.
Speaker 2 (09:25):
What sparked your interest in Chavez disease?
Speaker 3 (09:28):
Yeah, that's a hilarious question because, as
you know, I literally did sleepthrough this and parasitology,
because I said I'm never goingto practice in South America.
So I apologize, dr Craig, atTexas A&M, it just it kind of
fell in my lap and my staff'slap.
I mean I have to include.
I have an amazing team at work.
They're very, very loyal andhave stuck with me a long time
(09:54):
through this and have kind ofexperienced this.
But you know, long story short,we had a dog, one-year-old dog,
come in from the Humane Societyactually His name was Max, I'll
never forget him.
He was my gateway drug and hecame in with a tachyarrhythmia
and we were unable to save him.
Any drug we gave didn't work.
He succumbed and so I couldn'tsleep.
The next morning I came in and Iwas like God, you know, we,
we've got to figure out what'sgoing on here.
(10:14):
So we did an e-cropsy.
The shelter was kind enough tolet us do that and we we stopped
tissues, looked at everything.
Dog had a giant, dilated,purple heart, heavy, heavy,
heavy on on on the cut surface.
We sent it in for histopath.
It took them weeks and weeksand weeks, lots of internal
meetings.
This is about 25 years ago,about 23 years ago, and the end
(10:54):
result a month later was hey,this dog had T cruzi infection.
I guess what I had to go dustoff my head went to how many
cases, how many dogs have I beenseeing with heart disease or
not heart disease and beenmissing these?
So that started that process ofyou know it's the old adage,
right?
It's like if you don't look forit, you never find it, so you
never think you have it Right.
So we started looking for it.
(11:15):
Find it, so you never think youhave it right, so we started
looking for it.
And one thing that I wouldadvise veterinarians as you go
into the Chagas world it's likethe matrix right, once you take
the red pill, you're toast.
You can never go back.
So, fair warning, I warned you.
If you want to find Chagasdisease, the easiest way to find
it is and we all have thesecases just go back to your heart
disease patients that you'remanaging right now.
(11:36):
So do a little.
Who Got on your inventory andyour practice management
software and look at Pimobendin?
Whoever gets that.
You need to go test them.
Okay, this disease is a greatmimicker.
We've got plenty of dogs withmitral valve disease with Chagas
.
We've got plenty of dogs withDCM with it.
Okay, and that's not even goinginto the realm of cats, but
(11:57):
that's the easiest way to startlooking for Chagas disease.
So that one little dog, max.
That's what started the wholejourney and unfortunately
haven't looked back yet.
Speaker 2 (12:05):
So well done, max.
You said it's, you know, like23, 25 years ago, and then you
write this fabulous article and,oh, even though you're a key
opinion leader with all thatexperience, we always find
something surprising when we'reputting a manuscript together.
Was there anything that stuckout in this manuscript that's
surprising to you?
Speaker 3 (12:24):
Yeah, that's a great question, Lisa.
I never cease to be amazed.
I think that's why I still lovemy job.
You know, 24 years later, youknow you can always find some
things to challenge you on adaily basis.
The biggest surprise for me washow widespread this autonomic
dysfunction is.
Okay, and the second key pointis it didn't matter if the dog
(12:46):
was asymptomatic versussymptomatic.
Okay, there, we're going tofind that same amount of or not
the same amount, but we're goingto still find arrhythmias.
We're going to still find thesame amount of autonomic
disruption in there.
And it and it precluded, youknow, symptoms.
You got to understand these.
Like historically, people comein and they're like my dog's
fine, okay, I'm only testing,because you know my other, my
(13:08):
fourth dog, has Chagas and sureenough, you know they have
Chagas.
And I go through the historyagain.
Are you sure you know are weare?
We are we, you know, lethargic,you know decreased activity,
collapse, anything, nothing,nothing, nothing.
My physical exam is normal, myClinPath is normal, my imaging
is normal, yet here we go, right, and then you run the Holter
and you get back thesederangements and you're like,
(13:36):
wow, you know, and it affectedso many of the dogs, and you
know, in human medicine again,this is kind of new stuff for us
in veterinary medicine, but inhuman medicine we know it's a
well established fact thatderangements in HRV analysis, so
autonomic disruption, is adirect predictor of number one
progression of the disease andnumber two mortality.
So this is kind of importantstuff.
But it explains why dogs withchagas drop dead Okay, and I've
(14:00):
lost count of how many dogs I'veheard about from owners.
Is you know?
I gave my dog a bath they'redoing the zoomies, you know, in
the yard after the bath and thenthey drop dead, okay.
Or I went to bed and the dogwas fine and now he's dead, okay
, that happens very, veryfrequently, especially here in
the South, and so those are thebiggest surprises for me for
sure.
Speaker 1 (14:24):
You have me thinking back now to all my cardio cases.
Speaker 3 (14:25):
I'm like, hmm, I wonder if any of them had chagas
?
Yep, yep, and you know, if wedon't look for it again, we
don't find it right, but we tendto kind of get into the weeds,
right.
So that's another soapbox Ihave.
But, like you know, we startlooking at things like diet, you
know, and we're like, well,what about lentils and grain
free and stuff like that?
Yeah, but you're missing thepoint, right?
You know we have prevalencerates of Chagas in Texas in
(14:48):
companion animals and this is agrossly underdiagnosed number
because of the test platformsthat they've used in the papers
18%, so 18% of dogs in Texashave Chagas disease companion
animals, compared to about 16and a half with shelter dogs.
That we're talking millions ofdogs that are underdiagnosed and
the average, like our referencelab, we have a couple of them
(15:09):
that do the testing, serologybut the state lab, which is kind
of the tried and true, you know, set one, those guys test
probably, you know, a thousanddogs a year.
So how many are we missing,right?
Yeah?
Speaker 1 (15:22):
So crazy to think about, wow.
Well, thank you for doing thispodcast episode with us.
Hopefully this is prettyenlightening for folks.
Speaker 3 (15:27):
Yeah, I hope so, thank you.
Speaker 1 (15:28):
Yeah, of course, for those of you just joining us,
we're discussing heart ratevariability, derangements and
dogs with Chagas disease withour guest Roy.
Speaker 2 (15:36):
Roy, again back to you know 20, 25 years.
How has all that previoustraining and experience prepared
you to help write this article?
Speaker 3 (15:45):
previous training and experience prepared you to help
write this article.
Yeah, and again, I kind ofalluded to that earlier about
our training, right, formaltraining.
You know we were kind of given alittle bit different story
about Chagas disease.
I think the majority of my justexperience, you know, seeing it
on a, on a, literally I'm notexaggerating literally on a
daily basis when I'm in thehospital multiple cases of
(16:05):
Shiga's disease.
I think you know it's the gruntwork on the daily basis that we
see in our hospitals thattrains us to recognize these
patterns of disease.
And also, I think, on the humanside, you know we've got an
international team that we workwith for this kind of stuff and
they've been huge in opening upmy eyes.
(16:26):
So, again, drawing from theirexperience, um, connecting with
physicians, connecting withresearchers that are doing this,
and then taking all the piecesof the puzzle and putting them
together, um, I think that'sbeen my biggest um help with
education.
For myself is just just thewide variety of people in the
field that have helped me dothat People way smarter than me
(16:49):
and they've really done a goodjob of giving me their
information so we can help outwith it.
Speaker 1 (16:55):
So, roy, this next set of questions is going to be
really important for ourlisteners and you've given us a
wealth of information todayabout this disease.
But if you can really narrow itdown to like one piece of
information that theveterinarian needs to know when
they walk into the door to seethat client that may have a pet
with Chagas disease, what's onepiece of information the
veterinarian should know aboutheart rate variability
derangements in dogs with Chagasdisease?
Speaker 3 (17:16):
Sarah, I would say that the biggest one thing that
they could focus on is do yourcardiac assessment and look for
those arrhythmias.
Okay so you're going to knowyou're obviously not slapping a
halter on everybody as soon asthey walk in the door, but
you're going to be able todetect, through your physical
exam, those variabilities.
(17:37):
Okay so you may not be able toget it down to the millisecond
right Like the AI can do on thehalter, but you're going to be
able to detect thoseabnormalities in there.
So just do your auscultation,pay attention to that, and then
if you see anything abnormal,you know, think about Chagas.
Speaker 2 (17:54):
Good old physical exam.
Speaker 3 (17:56):
That's right.
Speaker 1 (17:58):
Tried and true.
And on the other side of therelationship, what's one thing
clients should know about Chagasdisease?
The relationship.
Speaker 3 (18:05):
What's one thing clients should know about Chagas
disease?
Yeah so, because there's thisis kind of an emerging disease.
Right, it's an important one,but it's an emerging disease and
so you know, your veterinarian,you might not have had very
much experience with it yet.
Okay.
So, as as a patient, as aclient, you are your dog or cat
or whatever your companionanimals number one advocate.
(18:26):
Okay.
So, if you have information, ifyou're listening to this podcast
, ask your veterinarian aboutChagas.
You know we're generally nicepeople, okay, so we'll, we'll do
what you want us to.
So just just say hey, I'd liketo have my dog tested for Chagas
disease.
Now, if you're living in Canada, okay.
Or you're living in Alaska andyou've never seen one of these
and then you don't have it,don't worry about it, okay.
(18:47):
But if you adopted your dogfrom here, you know, in the
South, you know you're traveling, you're doing agility work,
you're at the dog shows, youknow I mean, you're getting
exposed, your dog's gettingexposed, so so just just ask
your veterinarian and we'll,we'll look for those things.
You know, like I said, I learnthings every day.
My clients educate me a lot, soplease don't feel bad about
(19:07):
asking your veterinarian to testfor this.
Speaker 2 (19:10):
I can see Sarah smirking.
One of my favorite sayings isevery day is a school day.
Speaker 3 (19:14):
That's right Every day and it never stops right.
Speaker 2 (19:18):
That's what keeps us interested in our wonderful
profession.
Speaker 3 (19:21):
That's right.
Speaker 2 (19:21):
You read my mind, Lisa.
I know I can see the smirk.
Speaker 3 (19:26):
I call those growth opportunities.
You know another growthopportunity Great, super, here I
go again.
Speaker 2 (19:32):
I should be much taller than I am.
Speaker 3 (19:34):
That's right.
Speaker 2 (19:37):
Roy, thank you again, and as we wind down, we always
like to ask something just alittle more personal.
So for you, we'd like to knowwhat's the first concert you
attended.
Speaker 3 (19:45):
Oh yeah, that's a great question, lisa.
So 1992, I was in high schooland I'm dating myself the very
first concert I ever went to wasU2 in Houston, so that set the
bar really really high.
It's an amazing concert.
But yeah, a long time ago Ithink Bono was like the size of
a piece of sand.
That's how high up we were, butit was amazing.
Speaker 2 (20:07):
Did you get a chance to see them in the sphere?
Speaker 3 (20:10):
I did not.
Oh gosh, I was thinking aboutit.
Oh, it was so hard to resist,but I would have loved to see
them.
You know, a lot of years laterfor sure.
Speaker 1 (20:18):
Yeah, very cool, it's a fun question.
We actually haven't had thatone in a while, so thanks for
picking that one.
Speaker 3 (20:22):
Yeah, you're welcome.
Well, you asked me aboutpuzzles and I was like I don't
do puzzles.
That would be a boring answer.
Speaker 1 (20:28):
Yeah, that's an interesting one.
We have this theory where, like, internists do puzzles a
certain way and surgeons do it acertain way.
So, yeah, so, thank you so much, roy.
We appreciate you being herewith us today and sharing
information, too, about yourmanuscript with our listeners.
So thank you.
Speaker 3 (20:43):
Thank you, sarah Lisa .
Speaker 1 (20:46):
Appreciate you guys and to our listeners you can
read Roy's article on JAPMA.
I'm Sarah Wright with LisaFortier.
Be on the lookout for nextweek's episode and don't forget
to leave us a rating and reviewon Apple Podcasts or whatever
platform you listen to.
This is Veterinary Vertex, a podcast of the AVMA
Journals.
In this episode we chat aboutheart rate variability
derangements in dogs with Chagasdisease with Roy Madigan.
Speaker 2 (00:13):
Welcome listeners.
I'm Editor-in-Chief LisaFortier, and I'm joined by
Associate Editor Sarah WrightRoy.
Thank you so much for takingtime out of your busy schedule
to be with us here today.
Speaker 3 (00:23):
Thank you, Lisa and Sarah.
It's a pleasure to be here.
Speaker 1 (00:26):
All right, let's dive right in.
So, roy, your JABMA articlediscusses how heart rate
variability analysis may enhanceearly detection and management
of Chagas disease, which is anemerging One Health issue, by
addressing underdiagnosedautonomic and cardiac
dysfunction in dogs.
Please share with our listenersthe background on this article.
Speaker 3 (00:46):
Thanks, sarah.
Yeah, so for those listenersthat don't know much about
Chagas disease, or if you'relike me and you kind of slept
through that section inparasitology, just a brief
background Chagas disease is aparasitic disease.
Okay, it's caused by aprotozoal organism called
Chapanosoma cruzii.
So you know, not a virus, not abacteria, but a little tiny,
little microscopic bug similarto toxoplasma leishmania, if
(01:08):
you're over in Europe, and soit's.
It's pretty widespread as faras Southern United States.
The Southern 26 states,including Texas, which is where
I practice, is just inundatedwith it, and it's mainly because
we have the vector, and thatvector is called the kissing bug
or the triadamine bug.
So it's a little bit bigger orprobably in similar in size,
(01:30):
depending on where you are, to acockroach, but it's like a
giant mosquito it crawls, itflies and it takes blood meals,
and so wherever we find thatvector, you know we're going to
find the disease.
Generally, we're taught inveterinary school that it's a
disease of third world countries, and so you know, central
America, south America, but wehave quite a bit of it.
Essentially, what happens isthe parasite is in the hindgut
(01:53):
of this kissing bug, so it'sactually not transmitted through
the bite of the bug likeheartworm disease, but it's
spread through the feces.
So when this kissing bug takesa blood meal from its host,
whatever mammal it decides to do, it'll actually defecate, and
in that feces the parasite istransmitted into the bite wound
and then gets into circulation.
That's the classic transmission.
(02:15):
Other methods are a little bitmore effective in our companion
animals because they eateverything.
If you have a dog, you know howit goes.
They eat everything smallerthan themselves, especially when
these bugs have a nice crunchycenter with blood in it right.
So major reinforcement there.
And so these kissing bugs arecommonly ingested through the
oral route.
Other methods of transmissioninclude vertical transmission,
(02:38):
so from the bitch to the babieswe also had through blood
transfusions.
Obviously that's much lesscommon than on the human side,
and we also have carrioningestion, so eating stuff
they're not supposed to, whichI'm sure your dog's never done
before, and so those are prettycommon methods of transmission.
The parasite is very, veryeffective at getting into all
tissues.
(02:58):
So one common misconceptionwith Chagas disease is that it
only goes to the heart.
We tend to look at the heart alot because any amount of
myocarditis is bad, but itcauses inflammation in any
tissue that it goes to includingthe heart for myocarditis, and
so the disease that it causes ispretty simple.
(03:20):
Okay, it generally causes aprogressive chronic myocarditis.
Okay, if you think of it thatway, there's kind of like three
pillars that it operates in,okay, so by presence of the
parasite we cause tissue damage,so when those cells get
ruptured they die, right,regardless if it's in the liver,
the brain, the heart.
The second thing that it does isit causes inflammation, or what
(03:41):
we call the host immuneresponse, and so the body's
response to the disease or theparasite itself causes damage.
And then the last thing that itdoes is it causes some
microvascular disturbances, sotiny little microclots and all
the wonderful things that thosedo in tissues, okay, but the end
result, when we're talkingabout the heart, is generally
systolic dysfunction, eventuallyelectrical disturbances, which
(04:05):
is huge, okay, and then you know, over time we can get these
autonomic disruptions.
So our paper really focused onthese autonomic disruptions that
happen.
So more of a nervous systemeffect.
It really hasn't been looked atin dogs, and so that's what
kind of drove us to do thispaper and gather this data,
(04:27):
because we wanted to see, youknow, we know it happens in
humans, but does it happen indogs, and so it's very, very fun
to explore that.
Speaker 1 (04:36):
Yeah, thanks.
That was a great review.
Appreciate that.
So what are some of theimportant take-home messages
from this article?
Speaker 3 (04:43):
Yeah, I think the biggest thing that I'd like to
share with veterinarians youknow we obviously in private
practice don't do too manyHolter monitors, right, but
certainly everybody has accessto EKGs, ECGs, and hopefully
most of you are using those now.
You know, back when I graduateda long time ago, not too many
of us had ECGs for surgicalmonitoring, but that can be your
(05:04):
most reliable indicator ofearly detection for Chagas, you
know.
You know, classically thisdisease is diagnosed through
serology.
So we're going to be checkingthe body's response to the
parasites.
We're not looking for directparasites, necessarily.
We're looking for the antibodyresponse, right.
But the biggest red flag, atleast in our hospital, probably
a third of the cases that wediagnose are under anesthesia,
(05:26):
with arrhythmias, and so there'sa lot of papers out there that
look at arrhythmias.
You know the types, thefrequencies, all that.
But the biggest surprise for mewith this was that heart rate
variability analysis, which isjust a fancy term and a set of
tools that measure autonomicfunction in the heart, so
(05:49):
sympathetic versusparasympathetic, and there's
these distinct markers that havea lot of abbreviations.
There's a lot of math involvedwith it, but essentially, at the
end of the day, these justreflect the function of that
autonomic nervous system.
Okay.
So the the big take home is,you know, let's, let's kind of
(06:09):
expand our knowledge when we'relooking at these Holter reports,
when we're looking at HRVanalysis, instead of just
glossing over it and ignoring it.
You know, kind of really give ussome thought there.
If I see a derangement, if, ifI live in an area that's endemic
for Chagas disease again, it'slike if you're South of Oregon
and south of Pennsylvania,you're in that region, Okay.
Or if you have a dog with atravel history, maybe they
adopted the dog from the south,you know, maybe maybe you're in
(06:32):
like I've got a dog in Singaporeright now that we're treating.
I mean, how did that happen?
Right, so people travel aroundthe world and so if I'm, if I
have an abnormality in myphysical exam, I'm doing a
Holter monitor, or maybe thecardiologist is, you know, give
some extra thought to that andconsider maybe I'm dealing with
Chagas and I need to do a testfor that.
Speaker 2 (06:51):
Yeah, fascinating.
We recently did a podcast onRocky Mountain Spotted Fever and
how it's creeping its way intoplaces that it never was before
either, and I think that podcastand your article and this
podcast also really highlighthow important the role of the
veterinarian is in these OneHealth situations, to recognize
(07:14):
it in the animals as well as inpeople.
Speaker 3 (07:17):
Yeah, lisa, you bring up a fantastic point.
You know, dogs are sentinelsfor this disease across the
world.
We know that.
So when we look at dogs withChagas disease, it's always
associated with a higher risk ofinfection in their human
counterparts, right, and youknow, let's face it.
You know, when we were growingup, dogs lived outside.
Now they live in our bedroom,right, and so they bring in all
(07:40):
kind of fun creatures, includingkissing bugs.
You know these little vectorsand we see them, and you know
our clients see them in theirbedrooms, you know, and they
don't live in thatched huts,right, and so I don't know about
you guys, but we wereincorrectly taught in vet school
, and still are to this day,that this is a disease of third
world countries.
This is not.
You know, you can live in agated community and that gate
(08:02):
won't stop these kissing bugs,right, and so we've got to be
aware of that.
So the one health implicationsare huge.
Years of, you know, diagnosingand treating this disease.
I've only and we're talkingthousands of dogs, okay, but
I've only had six people thattested positive.
However, they would not havegotten tested if their dogs
(08:25):
didn't have it, and so hopefully, you know, their physicians
were able to intervene and helpthese people and, as far as I
know, they're all alive still.
So.
But dogs, dogs can help, youknow, dogs can help us.
Dogs can help us diagnose othermammals in the pack.
We've had a lot of cats, we'vehad a lot of horses and again
they would have gone undiagnosed.
In fact, in my own pack here Ihave three dogs.
(08:47):
I know that's weird, aveterinarian with only three
dogs.
One of our dogs, our goldenretriever, during her surgical
procedure at two and a half, wenoticed an arrhythmia that
triggered us to test.
She almost died.
She was in VTAC on the table.
That's not fun, but wediagnosed Chagas disease on her
(09:07):
and that triggered me to testthe other dogs and they were
also positive.
So you know, early detection iskey.
You know, and I think thisparticular set of indices, this
heart rate variability, lookingfor arrhythmias on your EKG or
Holter, is huge and it's goingto help us diagnose more
patients for sure.
Speaker 2 (09:25):
What sparked your interest in Chavez disease?
Speaker 3 (09:28):
Yeah, that's a hilarious question because, as
you know, I literally did sleepthrough this and parasitology,
because I said I'm never goingto practice in South America.
So I apologize, dr Craig, atTexas A&M, it just it kind of
fell in my lap and my staff'slap.
I mean I have to include.
I have an amazing team at work.
They're very, very loyal andhave stuck with me a long time
(09:54):
through this and have kind ofexperienced this.
But you know, long story short,we had a dog, one-year-old dog,
come in from the Humane Societyactually His name was Max, I'll
never forget him.
He was my gateway drug and hecame in with a tachyarrhythmia
and we were unable to save him.
Any drug we gave didn't work.
He succumbed and so I couldn'tsleep.
The next morning I came in and Iwas like God, you know, we,
we've got to figure out what'sgoing on here.
(10:14):
So we did an e-cropsy.
The shelter was kind enough tolet us do that and we we stopped
tissues, looked at everything.
Dog had a giant, dilated,purple heart, heavy, heavy,
heavy on on on the cut surface.
We sent it in for histopath.
It took them weeks and weeksand weeks, lots of internal
meetings.
This is about 25 years ago,about 23 years ago, and the end
(10:54):
result a month later was hey,this dog had T cruzi infection.
I guess what I had to go dustoff my head went to how many
cases, how many dogs have I beenseeing with heart disease or
not heart disease and beenmissing these?
So that started that process ofyou know it's the old adage,
right?
It's like if you don't look forit, you never find it, so you
never think you have it Right.
So we started looking for it.
(11:15):
Find it, so you never think youhave it right, so we started
looking for it.
And one thing that I wouldadvise veterinarians as you go
into the Chagas world it's likethe matrix right, once you take
the red pill, you're toast.
You can never go back.
So, fair warning, I warned you.
If you want to find Chagasdisease, the easiest way to find
it is and we all have thesecases just go back to your heart
disease patients that you'remanaging right now.
(11:36):
So do a little.
Who Got on your inventory andyour practice management
software and look at Pimobendin?
Whoever gets that.
You need to go test them.
Okay, this disease is a greatmimicker.
We've got plenty of dogs withmitral valve disease with Chagas
.
We've got plenty of dogs withDCM with it.
Okay, and that's not even goinginto the realm of cats, but
(11:57):
that's the easiest way to startlooking for Chagas disease.
So that one little dog, max.
That's what started the wholejourney and unfortunately
haven't looked back yet.
Speaker 2 (12:05):
So well done, max.
You said it's, you know, like23, 25 years ago, and then you
write this fabulous article and,oh, even though you're a key
opinion leader with all thatexperience, we always find
something surprising when we'reputting a manuscript together.
Was there anything that stuckout in this manuscript that's
surprising to you?
Speaker 3 (12:24):
Yeah, that's a great question, Lisa.
I never cease to be amazed.
I think that's why I still lovemy job.
You know, 24 years later, youknow you can always find some
things to challenge you on adaily basis.
The biggest surprise for me washow widespread this autonomic
dysfunction is.
Okay, and the second key pointis it didn't matter if the dog
(12:46):
was asymptomatic versussymptomatic.
Okay, there, we're going tofind that same amount of or not
the same amount, but we're goingto still find arrhythmias.
We're going to still find thesame amount of autonomic
disruption in there.
And it and it precluded, youknow, symptoms.
You got to understand these.
Like historically, people comein and they're like my dog's
fine, okay, I'm only testing,because you know my other, my
(13:08):
fourth dog, has Chagas and sureenough, you know they have
Chagas.
And I go through the historyagain.
Are you sure you know are weare?
We are we, you know, lethargic,you know decreased activity,
collapse, anything, nothing,nothing, nothing.
My physical exam is normal, myClinPath is normal, my imaging
is normal, yet here we go, right, and then you run the Holter
and you get back thesederangements and you're like,
(13:36):
wow, you know, and it affectedso many of the dogs, and you
know, in human medicine again,this is kind of new stuff for us
in veterinary medicine, but inhuman medicine we know it's a
well established fact thatderangements in HRV analysis, so
autonomic disruption, is adirect predictor of number one
progression of the disease andnumber two mortality.
So this is kind of importantstuff.
But it explains why dogs withchagas drop dead Okay, and I've
(14:00):
lost count of how many dogs I'veheard about from owners.
Is you know?
I gave my dog a bath they'redoing the zoomies, you know, in
the yard after the bath and thenthey drop dead, okay.
Or I went to bed and the dogwas fine and now he's dead, okay
, that happens very, veryfrequently, especially here in
the South, and so those are thebiggest surprises for me for
sure.
Speaker 1 (14:24):
You have me thinking back now to all my cardio cases.
Speaker 3 (14:25):
I'm like, hmm, I wonder if any of them had chagas
?
Yep, yep, and you know, if wedon't look for it again, we
don't find it right, but we tendto kind of get into the weeds,
right.
So that's another soapbox Ihave.
But, like you know, we startlooking at things like diet, you
know, and we're like, well,what about lentils and grain
free and stuff like that?
Yeah, but you're missing thepoint, right?
You know we have prevalencerates of Chagas in Texas in
(14:48):
companion animals and this is agrossly underdiagnosed number
because of the test platformsthat they've used in the papers
18%, so 18% of dogs in Texashave Chagas disease companion
animals, compared to about 16and a half with shelter dogs.
That we're talking millions ofdogs that are underdiagnosed and
the average, like our referencelab, we have a couple of them
(15:09):
that do the testing, serologybut the state lab, which is kind
of the tried and true, you know, set one, those guys test
probably, you know, a thousanddogs a year.
So how many are we missing,right?
Yeah?
Speaker 1 (15:22):
So crazy to think about, wow.
Well, thank you for doing thispodcast episode with us.
Hopefully this is prettyenlightening for folks.
Speaker 3 (15:27):
Yeah, I hope so, thank you.
Speaker 1 (15:28):
Yeah, of course, for those of you just joining us,
we're discussing heart ratevariability, derangements and
dogs with Chagas disease withour guest Roy.
Speaker 2 (15:36):
Roy, again back to you know 20, 25 years.
How has all that previoustraining and experience prepared
you to help write this article?
Speaker 3 (15:45):
previous training and experience prepared you to help
write this article.
Yeah, and again, I kind ofalluded to that earlier about
our training, right, formaltraining.
You know we were kind of given alittle bit different story
about Chagas disease.
I think the majority of my justexperience, you know, seeing it
on a, on a, literally I'm notexaggerating literally on a
daily basis when I'm in thehospital multiple cases of
(16:05):
Shiga's disease.
I think you know it's the gruntwork on the daily basis that we
see in our hospitals thattrains us to recognize these
patterns of disease.
And also, I think, on the humanside, you know we've got an
international team that we workwith for this kind of stuff and
they've been huge in opening upmy eyes.
(16:26):
So, again, drawing from theirexperience, um, connecting with
physicians, connecting withresearchers that are doing this,
and then taking all the piecesof the puzzle and putting them
together, um, I think that'sbeen my biggest um help with
education.
For myself is just just thewide variety of people in the
field that have helped me dothat People way smarter than me
(16:49):
and they've really done a goodjob of giving me their
information so we can help outwith it.
Speaker 1 (16:55):
So, roy, this next set of questions is going to be
really important for ourlisteners and you've given us a
wealth of information todayabout this disease.
But if you can really narrow itdown to like one piece of
information that theveterinarian needs to know when
they walk into the door to seethat client that may have a pet
with Chagas disease, what's onepiece of information the
veterinarian should know aboutheart rate variability
derangements in dogs with Chagasdisease?
Speaker 3 (17:16):
Sarah, I would say that the biggest one thing that
they could focus on is do yourcardiac assessment and look for
those arrhythmias.
Okay so you're going to knowyou're obviously not slapping a
halter on everybody as soon asthey walk in the door, but
you're going to be able todetect, through your physical
exam, those variabilities.
(17:37):
Okay so you may not be able toget it down to the millisecond
right Like the AI can do on thehalter, but you're going to be
able to detect thoseabnormalities in there.
So just do your auscultation,pay attention to that, and then
if you see anything abnormal,you know, think about Chagas.
Speaker 2 (17:54):
Good old physical exam.
Speaker 3 (17:56):
That's right.
Speaker 1 (17:58):
Tried and true.
And on the other side of therelationship, what's one thing
clients should know about Chagasdisease?
The relationship.
Speaker 3 (18:05):
What's one thing clients should know about Chagas
disease?
Yeah so, because there's thisis kind of an emerging disease.
Right, it's an important one,but it's an emerging disease and
so you know, your veterinarian,you might not have had very
much experience with it yet.
Okay.
So, as as a patient, as aclient, you are your dog or cat
or whatever your companionanimals number one advocate.
(18:26):
Okay.
So, if you have information, ifyou're listening to this podcast
, ask your veterinarian aboutChagas.
You know we're generally nicepeople, okay, so we'll, we'll do
what you want us to.
So just just say hey, I'd liketo have my dog tested for Chagas
disease.
Now, if you're living in Canada, okay.
Or you're living in Alaska andyou've never seen one of these
and then you don't have it,don't worry about it, okay.
(18:47):
But if you adopted your dogfrom here, you know, in the
South, you know you're traveling, you're doing agility work,
you're at the dog shows, youknow I mean, you're getting
exposed, your dog's gettingexposed, so so just just ask
your veterinarian and we'll,we'll look for those things.
You know, like I said, I learnthings every day.
My clients educate me a lot, soplease don't feel bad about
(19:07):
asking your veterinarian to testfor this.
Speaker 2 (19:10):
I can see Sarah smirking.
One of my favorite sayings isevery day is a school day.
Speaker 3 (19:14):
That's right Every day and it never stops right.
Speaker 2 (19:18):
That's what keeps us interested in our wonderful
profession.
Speaker 3 (19:21):
That's right.
Speaker 2 (19:21):
You read my mind, Lisa.
I know I can see the smirk.
Speaker 3 (19:26):
I call those growth opportunities.
You know another growthopportunity Great, super, here I
go again.
Speaker 2 (19:32):
I should be much taller than I am.
Speaker 3 (19:34):
That's right.
Speaker 2 (19:37):
Roy, thank you again, and as we wind down, we always
like to ask something just alittle more personal.
So for you, we'd like to knowwhat's the first concert you
attended.
Speaker 3 (19:45):
Oh yeah, that's a great question, lisa.
So 1992, I was in high schooland I'm dating myself the very
first concert I ever went to wasU2 in Houston, so that set the
bar really really high.
It's an amazing concert.
But yeah, a long time ago Ithink Bono was like the size of
a piece of sand.
That's how high up we were, butit was amazing.
Speaker 2 (20:07):
Did you get a chance to see them in the sphere?
Speaker 3 (20:10):
I did not.
Oh gosh, I was thinking aboutit.
Oh, it was so hard to resist,but I would have loved to see
them.
You know, a lot of years laterfor sure.
Speaker 1 (20:18):
Yeah, very cool, it's a fun question.
We actually haven't had thatone in a while, so thanks for
picking that one.
Speaker 3 (20:22):
Yeah, you're welcome.
Well, you asked me aboutpuzzles and I was like I don't
do puzzles.
That would be a boring answer.
Speaker 1 (20:28):
Yeah, that's an interesting one.
We have this theory where, like, internists do puzzles a
certain way and surgeons do it acertain way.
So, yeah, so, thank you so much, roy.
We appreciate you being herewith us today and sharing
information, too, about yourmanuscript with our listeners.
So thank you.
Speaker 3 (20:43):
Thank you, sarah Lisa .
Speaker 1 (20:46):
Appreciate you guys and to our listeners you can
read Roy's article on JAPMA.
I'm Sarah Wright with LisaFortier.
Be on the lookout for nextweek's episode and don't forget
to leave us a rating and reviewon Apple Podcasts or whatever
platform you listen to.
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