February 18, 2025 • 26 mins
Are you overlooking azotemia in hyperthyroid cats? Explore the intriguing world of feline hyperthyroidism with veterinary endocrinologist Mark Peterson, who sheds light on why some hyperthyroid cats developing azotemia post-radioiodine treatment face shorter survival times. We'll challenge previous assumptions and dive into new research involving over 1,000 cats, revealing insights that are crucial for making informed treatment decisions for these beloved pets. Uncover the complexities of diagnosing concurrent chronic kidney disease and the critical role of factors like increased blood flow, muscle mass loss, and subsequent treatment options, including medical and dietary therapies.
In our conversation, Mark also takes us on his personal journey into endocrinology and his impactful contributions to feline health over the past four decades. As we look to the future, we discuss the potential advancements in diagnosing and managing azotemia, including the promising but cautious role artificial intelligence might play in veterinary research. Join us for a captivating discussion on the challenges of recognizing hypothyroidism in cats and the ongoing efforts to improve survival rates through innovative treatments, all backed by Mark’s extensive experience and passion for unraveling the mysteries of hyperthyroidism in cats.
Open Access JAVMA article: https://doi.org/10.2460/javma.24.10.0653
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Transcript
Episode Transcript
Available transcripts are automatically generated. Complete accuracy is not guaranteed.
Sarah Wright (00:01):
You are listening to Veterinary Vertex, a podcast
of the AVMA Journals.
In this episode, we chat abouthow hyperthyroid cats that
develop azotemia followingsuccessful radioiodine treatment
have shorter survival timescompared to cats that remain
non-azotemic, with our guest,Mark Peterson.
Lisa Fortier (00:19):
Welcome to Veterinary Vertex.
I'm Editor-in-Chief LisaFortier, and I'm joined by
Associate Editor Sarah Wright.
Today we have Mark joining usfrom Chile, Pennsylvania.
Mark, thank you so much fortaking time out of your day to
be with us here today.
Mark Peterson (00:33):
Thank you, Lisa and Sarah.
It's really a pleasure to behere to talk to you today.
Sarah Wright (00:37):
All right, let's dive right in.
So, Mark, I found your articleespecially interesting because
(00:57):
one of my cats, whenever we getour blood work done like
semi-annually her thyroid isalways kind of on the cusp of
being hyperthyroid.
and were like kind of justwaiting until she goes over the
edge so for my own knowledge, Ifound this very interesting.
In your article discusses howhyperthyroid cats that develop
azotemia following successfulradioiodine treatment have
shorter survival times comparedto cats that remain non-azotemic
.
Please share with our listenersthe background on this article.
Mark Peterson (01:18):
So what we know is that multiple studies have
shown that between 15 and 50percent of hyperthyroid cats
will have concurrent chronickidney disease, or CKD.
The problem withhyperthyroidism is it's more
difficult to confirm or diagnosethis concurrent CKD for a
number of reasons.
First of all, hyperthyroidismincreases the blood flow from
(01:41):
the heart, so it increases theblood flow to the kidneys,
increases GFR or the pressure ofthe kidneys.
That increased pressure andincreased blood flow tends to
lower the serum creatinine,serum BUN concentrations and you
may have a cat with CKD.
That we all think is verynormal because when they're
(02:04):
hyperthyroid the numbers tend togo down and look better.
In addition, hyperthyroid catscommonly lose weight, including
muscle mass.
Creatinine is derived frommuscle creatine, so as muscle
mass goes down, serum creatininewill also fall.
So again, if you have a catwith CKD or chronic kidney
(02:26):
disease, it's very common,because of their muscle loss, to
have a lowering in their serumcreatinine concentrations.
So this overall, it can be verydifficult to know for sure if
that hyperthyroid cat as CKD ornot.
It's well known thathyperthyroid cats that are
(02:49):
azotemic at diagnosis in otherwords, you have a hyperthyroid
cat.
The T4 is high, the creatinineis also high, as we define that
greater than two.
Those cats are well known tohave a poorer prognosis.
Generally, they survive with amedian survival time of less
than two years, which is notnearly as high as those without
(03:13):
azotemia.
But one study done about adecade ago and this was
castrated with methimazole foundthat hyperthyroid cats seemed
to be different.
Those that developed azotemiaafter treatment with methimazole
did not have a shorter survivaltime than those that didn't
(03:37):
have azotemia.
And, to be honest, this reallydidn't make any sense to me at
all, because we know that youthyroid cats not cats, your
regular cat with not ahyperthyroidism, that has even
stage two to three early chronickidney disease those cats have
(03:57):
a shorter survival time.
So it didn't make sense thathyperthyroid cats would be
different just when they havehyperthyroidism.
So and this wasn't my clinicalimpression either so in this
study the goal really was tostudy a larger number of cats
and in this study we studiedover 1,000 cats followed from
(04:19):
the time they were diagnosed towhen they developed azotemia
between 6 to 12 months untilthey died.
So we looked at these cats overabout a 10-year period to try
to make sense of this and seewhat we found.
Sarah Wright (04:36):
Yeah, super interesting study and, I think,
very clinically applicable too.
So what are some of theimportant take-home messages
from this JAVMA article?
Mark Peterson (04:44):
Well, my clinical impression was right, if you
believe the study, because whenwe looked at our cats that
developed CKD or developedazotemia, defined as a
creatinine concentration greaterthan 2 at 6 to 12 months after
radiolidon treatment, theirsurvival time was one and a half
(05:09):
years shorter than those catsthat didn't become azotemic at
that time.
So survival time between thetwo groups was 4.3 years in the
cats that didn't developazotemia to 2.8 years in those
that did so.
This isn't to say that all catsthat become azotemic after we
(05:30):
treat them are going to dieimmediately and it's a terrible
thing to necessarily treat them.
They should be treated in somefashion.
But it's important that theowners realize this and the
veterinarians realize that theirsurvival time will be shorter
and that may influence how wemanage these cats and how we
treat them, what treatment we wechoose.
(05:52):
Maybe we don't want to treatall these cats with radio iodine
.
Maybe some of them should betreated medically or dietary
wise or something else.
Lisa Fortier (06:04):
Congratulations on a manuscript that's going to
change clinical practice.
Sometimes we do a lot ofstudies, but this one's really
going to move the needle, sothank you for sharing it with us
at JAVMA as well.
Mark Peterson (06:14):
Well, thank you for accepting it.
Lisa Fortier (06:18):
You're clearly a really good clinical educator.
I'm an equine orthopedicsurgeon, so the last time I
thought about the neuroendocrineaxis was a long time ago, and
even I understand what you'retalking about.
What sparked your interest inendocrinology?
Mark Peterson (06:33):
Well, you know, I went to school I graduated in
1976.
And you know, in veterinaryschool I loved endocrinology.
I liked diabetes and Cushing'sin dogs, for instance.
And so when I did an internshipand then a residency at the
Animal Medical Center in NewYork, and during my first year
(06:54):
residency I got involved in aclinical research project with a
physician studying canineCushing's disease and that was
very interesting and I for yearsI was probably one of the
world's top investigators forcanine Cushing's disease too.
But in 1979, we discovered ourfirst hyperthyroid cat and I was
(07:23):
lucky because of thisrelationship I had working with
this physician on canineCushing's disease.
I was doing endocrine roundswith physicians at the New York
Hospital Presbyterian in NewYork City.
So when we first had thishyperthyroid cat, I went to one
of the thyroidologists on roundsand I said we have this cat
(07:46):
with hyperthyroidism.
What do you think?
What should I do?
How should I work it up, whatwe should do?
And they were extremely helpfuland interested and I started a
collaboration with these guyswho were, you know, I couldn't
have done what we've done withhyperthyroidism without them.
So that's after once we startedhyperthyroidism, my interest in
(08:08):
Cushing's went way down andhyperthyroidism went way up.
Here's a new disease no oneknew nothing about and we were
seeing it.
The first year we saw about 10cats, and the next year we saw
about 100 cats, and the yearafter that it just kept going up
(08:28):
and up and up.
So you know, right now it's themost common endocrine disease
in cats and it's one of the mostcommon diseases we see in older
cats.
Cats are older than 10 years ofage.
One in 10 of those cats will behyperthyroid, so it's a very
important disease.
Lisa Fortier (08:49):
Fantastic, what a fabulous career.
It's so great to be aveterinarian and contribute and
collaborate with MDs and bringthat one health approach.
Yeah, move the needle on bothsides, mark.
Every time we do a study, likeSarah asked you earlier about
what some of the most importantfindings are, but we're always
surprised by something.
If you're really thinking aboutthe data, what surprised you
(09:10):
from this article?
Mark Peterson (09:14):
I think the biggest thing that I mean.
This happens every time I writean article like this where
we're dealing withhyperthyroidism and kidney
disease and that's how some ofthe cats that became azotemic I
would never have thought theywere.
You know there's, sometimesthere's.
You know, if you have a cathyperthyroid cat that's
(09:36):
untreated and has a creatininein the upper third of the
reference interval or has adilute specific gravity or has
polyuria or polygipsia PUPD, youknow you can suspect
hypothyroidism.
Some of these cats were notthat old, they had none of this
and they still went on to becomeazotemic.
(09:56):
So there's just not a perfectway to make the diagnosis until
we treat them.
It surprised me in this article, like it surprised me in the
past.
They're just not a good way.
But that said, looking at serumcreatinine, looking at BUN,
looking at specific gravity justthe things that all
(10:17):
practitioners can do and shoulddo that can be very, very
helpful.
And if you have a cat with alow specific gravity and the
creatinine is approaching thattwo limit, you know you have to
be very, very careful and thoseare the cats that we want to
really monitor very carefullyafter treatment.
Sarah Wright (10:35):
I think this episode is a good reminder to
clinicians.
Just to keep an open mind.
Don't take things off your listtoo early.
Always consider the wholeclinical picture.
Mark Peterson (10:43):
I agree.
Sarah Wright (10:46):
So what are the next steps for research in this
topic?
Mark Peterson (10:51):
Well, we're doing some studies now, or really are
done, that I'm writing up,where we're looking at not just
euthyroid cats but we're lookingat survival of cats with
hypothyroidism, becausehypothyroidism is relatively
common after we treat withradioidine.
And that muddles the picturebecause some of that azotemia
(11:13):
that can develop in hypothyroidcats can be pre-renal, because
hypothyroid cats have anincreased GFR, an increased
renal blood flow.
So once we treat thosehypothyroid cats they fall,
hopefully to normal.
But hypothyroid cats itcontinues to fall so they can
have a decreased renal bloodflow and a decreased gfr.
(11:37):
So that even makes the azotemialook worse than it really is
because of the pre-renalcomponent.
So I don't, we're looking we.
What we want to publish next isour findings, a long-term
follow-up of those cats, howthose cats can also become
azotemic and how treatment withthyroid hormone replacement can
(11:58):
help both their survival.
And I think in large partbecause we're helping with the
azotemia, because as we treatwith, as we supplement those
hypothyroid cats with LT4,thyroid hormone supplementation,
the azotemia gets better and itseems like the progression of
the CKD slows.
(12:18):
But those you know, that'sanother paper.
Sarah Wright (12:22):
Well, we look forward to hopefully receiving
more manuscripts from you.
Mark Peterson (12:27):
That's only, that's only the only job.
That's the only place I want togo.
Sarah Wright (12:32):
We're happy to hear that.
So this is.
The next question is somethingwe've been asking a lot of our
interviewees lately.
Just with the rise of differentemerging technologies and such,
do you see a role for AI inthis area of research?
Mark Peterson (12:46):
definitely, definitely, because there may be
something that I'm missing as aclinician that AI will help.
You know some absurd littlething in the serum chemistry
profile that I'm missing thatcould help us do it.
So I think we should look at it, and I say that being someone
(13:07):
who is kind of well, I wasreally very against AI, and now
I've been using it more and youknow, I'm I'm still, I'm always,
I'm always frightened about thefalse facts that can spit back
if you don't know what you'reasking.
Uh, but I've also found it tobe very, very helpful for me in
(13:29):
my work, so I'm excited to getmore and more involved with AI.
Sarah Wright (13:36):
Very cool and, for those of you just joining us,
we're discussing howhyperthyroid cats that develop
azotemia following successfulradioiodine treatment have
shorter survival times comparedto cats that remain non-azotemic
with our guest Mark.
Lisa Fortier (13:52):
Mark, what I've really enjoyed hearing you say
is how curious you've been ableto maintain, since you got your
veterinary degree and workedwith the MDs, just like thinking
, huh, that doesn't make sense.
How come that is?
And what about that?
How did all that combinedtraining help you keep that
(14:12):
curiosity and then get acrossthe finish line with all the
many, many manuscripts you'vewritten?
Mark Peterson (14:20):
I mean, I've always asked.
You know, when I was an intern,one of my staff members and I
won't mention his name becausehe may be embarrassed by this
but he told me once that I askedtoo many questions.
And he told me once I better doa residency and go on, because
(14:40):
maybe I should go to a vetschool and be an academic,
because all I did was askquestions.
And I've always asked questions, I've always been curious.
Lisa Fortier (14:52):
Did anybody call you Horshack?
Do you remember Horshack?
Mark Peterson (14:55):
No, but they probably should have.
So for me, the clinical, I meanI love, really, I love taking
care of hyperthyroid cats.
I really I love cats, right.
So that's fun for me.
But it's the clinical researchand learning and trying to get
(15:17):
to the next stage to help them.
I mean, when we discovered thisdisease in the late 70s, we
knew nothing.
We knew nothing.
We thought it was a raredisease that was going to go
away pretty soon and it'sbecoming a worldwide epidemic,
you know.
So there's so much more tolearn.
(15:38):
I thought my goal in my careerwas to try to figure out the
cause and and make the diseasego away, and that hasn't
happened.
In that regard, I failed, but Ialso have a lot of other people
helping me now, so hopefully wewill figure this out.
But it's, it's been fun, it'sbeen.
I've been doing this for 45years, doing the clinical
(16:00):
research on these cats, and it'sdon't know why I find it fun,
but I do, I really do.
I love what I do.
Lisa Fortier (16:11):
What's your gut instinct as to the cause?
I've been thinking about thatthis whole time.
Mark Peterson (16:18):
I don't think it's one thing First of all,
it's older age.
When we first, when, when themedian, when we, when we first I
wrote our first paper, uh, thein these cats and the average
age has always been about 12years, about age the 12 years at
(16:40):
that time was was an old cat.
We used to say look at this cat, he's 12 years and he's
hyperthyroid.
And people would come in andsay that's really an old cat.
Are you sure you want to treatthat old cat?
Well now, 12 years is not old,that's middle age.
So we did a study and between1983 and 1993 at the Animal
(17:04):
Medical Center, the reviewermade us do this work.
We did our whole hospitalpopulation.
You know, in the Animal MedicalCenter at that time we saw
about 100,000 pets a year.
So we had a lot of cats to lookat.
The average age of our hospitalpopulation in that 10-year
(17:25):
period went up by four years.
That's how much we've advancedveterinary medicine.
And that was in the 80s.
That's continued to happen.
So what's causing it?
Part of it is, I think catscould have always had this first
of all, but they just neverlive long enough, just like you
(17:45):
and I never used to get heartattacks because we would die or
be eaten by a lion in our family.
Right now, we live longer, sowe can die of some of these
other diseases.
That's one thing, but I don'tthink that's all um.
There's stuff in the, in the,you know, in in the 70s that's
when cat food was still startingto come out um, all these
(18:07):
synthetic compounds, theplasticizers, the bpa, all these
chemicals that are now soambiguous.
They were that they were, justthey weren't there before.
And we've shown that some ofthese um flame retardants that
tend to accumulate in dust.
We've done some studies, one ofwhich we put a collar around
(18:27):
the cat's neck and we didcontrol cats and hyperthyroid
cats, and the hyperthyroid catshad significantly higher flame
retardants exposure than theother cats.
So I think it's a combinationbetween their age, their
genetics.
Obviously there's something ingenetics because some breeds are
(18:48):
less likely to get hyperthyroidthan others, notably like the
Siamese and other Orientalbreeds.
So age, genetics, environmentwith the chemicals in the
environment and probably die.
You know, we've heard a lotabout these highly processed
compounds in food that are badfor us.
What about cat food?
(19:09):
The same thing is probably truethere.
People really haven't looked atit.
Lisa Fortier (19:15):
Well, thank you for sharing your insight.
Sarah Wright (19:19):
So, Mark, this next set of questions is going
to be very important for ourlisteners, and the first one is
dealing with the veterinarian'sperspective.
What is one piece ofinformation the veterinarian
should know about hyperthyroidcats that develop azotemia
following successful radioiodinetreatment?
Mark Peterson (19:37):
Well, you know, as I said before, if you have a
hyperthyroid cat that's alreadyazotemic, that cat has a.
Fairly the prognosis is notvery good.
If we treat them they generallylive less than two years.
So the prognosis isn't great.
But as long as they're notazotemic prior to treatment, as
(19:59):
long as that creatinineespecially if the creatinine is
less than 1.5 or less than 1.8,kind of in the mid to low range
and then they do become azotemic, this unmasking of the azotemic
chronic kidney disease isn'tnecessarily a death sentence.
Some of those cats live a longtime.
The median survival was 2.8years, so almost three years in
(20:22):
these cats.
So they can still live a longtime.
So why is it important to knowthis?
It's important to know itbecause we want to pick it up as
soon as we can so we can startto manage it.
So if they have chronic kidneydisease we may want to start
them and die.
There's other drugs to maybehelp kidney function improve, so
(20:43):
at least stabilize it.
But again, the important thingis that we can't predict very
well, at least right now, andthat's what AI may help.
But AI or not, I still thinkthere's going to be cases that
we're going to be surprised thatthis cat became azotamic, but
(21:03):
he did so.
Now we have to deal with it.
So close monitoring, earlyidentification, is really
important for that veterinarianto know.
You can't treat with radiowire,dine and forget the cat saying
well, he's got to be cured.
Now we have to look.
We want to monitor for threereasons.
We want to monitor for threereasons.
(21:24):
We want to monitor afterradiowire, as I tell my owners
and veterinarians we want tomake sure the T4 falls to normal
, the thyroid levels fall tonormal.
We want to make sure that thecreatinine and BUN stay normal
and don't start to go up,because if they start to go up
we have to address that.
(21:46):
And then, as I alluded toearlier, we also want to make
sure they're not becominghypothyroid.
So, to do that we always, forthe first year after we treat,
we always do a serum T4 and aserum thyroid stimulating
hormone concentration.
Because a high TSH or thyroidstimulating hormone
concentration is the best andeasiest way we can identify
(22:09):
hypothyroidism.
And if those cats becomehypothyroid then we want to
start treatment and that's goingto help the hypothyroidism.
It's always also going to helpprogression of their azotemia,
if they have it.
Sarah Wright (22:23):
Very well said.
So you kind of answered thisalready a little bit.
But what's one thing clientsshould know about this?
If you could boil it down tolike one important take-home
that clients should consider.
Mark Peterson (22:34):
Well, first of all, remember they have to be in
charge it's kind of like ofyour own health or your mother's
health and so forth.
So this is if their cat hasbeen treated with radioiodine,
they need to know that theirveterinarian may be a very good
(22:56):
veterinarian, but this could allslip through the tracks.
So they have to remember thatit's their responsibility to go
in, make the appointments formodulatory, make sure the right
tests are done, make sure thatthyroid function's looked at,
including the TSH, as we justtalked about, make sure that
renal function is addressed andlooked at.
(23:16):
And you know, in my practice,all the cats that we treat, we
encourage the veterinarians tosend me the results and I will
gladly interpret them and helpthem and advise them as we go
along.
They're not my—I considerthem—they're patient, but I
(23:38):
still would like to be involvedand probably know a little bit
more about this than many ofthem do.
So I like to still be involvedand help however I can.
Lisa Fortier (23:47):
That's very generous of you.
I've super enjoyed talking toyou and remembering some of
these things and just learninghow you've moved the needle so
much throughout your career, andthank you again for sharing
your information with JAVMA.
Mark Peterson (24:01):
Thank you for having me.
Lisa Fortier (24:03):
As we wind down, we like to ask a little more of
a personal question, and I'mgoing to guess yours is going to
be about a bird, given yourbackground.
What's your favorite animalfact?
Mark Peterson (24:14):
Well, it's about cats, of course.
Lisa Fortier (24:16):
Oh, of course, silly Lisa.
Mark Peterson (24:20):
So one thing that I like to tell people is the
way.
It's not widely known that catsand the way they communicate
with us, their owners, isdifferent than the way they
communicate with other cats.
When cats communicate withother cats, they do it through
their body language, their scent, they may have vocal cues, but
(24:44):
they don't normally meow atother cats, where my cats have
always meowed and screamed anddemanded stuff.
And this is something the catshave learned in their
interaction with humans.
So, the way they address us andspeak to us is learn from us.
It's not normally how theywould work with other cats.
They don't need to, they can.
(25:05):
They have their own, their ownways to do it through their
scent and body language and soforth.
So I again, like I, I justreally I love working with the
cats.
That's been, that's been that I, I just that's been made my
career and finding this diseaseearly on and spending my life
(25:25):
doing this has been very muchfun.
I've really enjoyed my career.
Lisa Fortier (25:30):
That's awesome.
Well, we compliment each otherwell, because I'm deathly afraid
of mean cats and it's one ofthe reasons I went into equine.
So they're all yours, buddy.
Mark Peterson (25:39):
Okay, well, you know something I've had a few
mean horses, and I'm glad thatsomeone's there to take care of
the horses too.
Sarah Wright (25:48):
Look at that, it goes both ways.
Yes, well, thank you so much,Mark.
Really appreciate you beinghere today and just sharing your
enthusiasm for this researchwith us.
Mark Peterson (25:57):
You're welcome.
Thank you very much again forhaving me.
Sarah Wright (26:00):
And to our listeners.
You can read Mark's article inJAVMA.
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.
You are listening to Veterinary Vertex, a podcast
of the AVMA Journals.
In this episode, we chat abouthow hyperthyroid cats that
develop azotemia followingsuccessful radioiodine treatment
have shorter survival timescompared to cats that remain
non-azotemic, with our guest,Mark Peterson.
Lisa Fortier (00:19):
Welcome to Veterinary Vertex.
I'm Editor-in-Chief LisaFortier, and I'm joined by
Associate Editor Sarah Wright.
Today we have Mark joining usfrom Chile, Pennsylvania.
Mark, thank you so much fortaking time out of your day to
be with us here today.
Mark Peterson (00:33):
Thank you, Lisa and Sarah.
It's really a pleasure to behere to talk to you today.
Sarah Wright (00:37):
All right, let's dive right in.
So, Mark, I found your articleespecially interesting because
(00:57):
one of my cats, whenever we getour blood work done like
semi-annually her thyroid isalways kind of on the cusp of
being hyperthyroid.
and were like kind of justwaiting until she goes over the
edge so for my own knowledge, Ifound this very interesting.
In your article discusses howhyperthyroid cats that develop
azotemia following successfulradioiodine treatment have
shorter survival times comparedto cats that remain non-azotemic
.
Please share with our listenersthe background on this article.
Mark Peterson (01:18):
So what we know is that multiple studies have
shown that between 15 and 50percent of hyperthyroid cats
will have concurrent chronickidney disease, or CKD.
The problem withhyperthyroidism is it's more
difficult to confirm or diagnosethis concurrent CKD for a
number of reasons.
First of all, hyperthyroidismincreases the blood flow from
(01:41):
the heart, so it increases theblood flow to the kidneys,
increases GFR or the pressure ofthe kidneys.
That increased pressure andincreased blood flow tends to
lower the serum creatinine,serum BUN concentrations and you
may have a cat with CKD.
That we all think is verynormal because when they're
(02:04):
hyperthyroid the numbers tend togo down and look better.
In addition, hyperthyroid catscommonly lose weight, including
muscle mass.
Creatinine is derived frommuscle creatine, so as muscle
mass goes down, serum creatininewill also fall.
So again, if you have a catwith CKD or chronic kidney
(02:26):
disease, it's very common,because of their muscle loss, to
have a lowering in their serumcreatinine concentrations.
So this overall, it can be verydifficult to know for sure if
that hyperthyroid cat as CKD ornot.
It's well known thathyperthyroid cats that are
(02:49):
azotemic at diagnosis in otherwords, you have a hyperthyroid
cat.
The T4 is high, the creatinineis also high, as we define that
greater than two.
Those cats are well known tohave a poorer prognosis.
Generally, they survive with amedian survival time of less
than two years, which is notnearly as high as those without
(03:13):
azotemia.
But one study done about adecade ago and this was
castrated with methimazole foundthat hyperthyroid cats seemed
to be different.
Those that developed azotemiaafter treatment with methimazole
did not have a shorter survivaltime than those that didn't
(03:37):
have azotemia.
And, to be honest, this reallydidn't make any sense to me at
all, because we know that youthyroid cats not cats, your
regular cat with not ahyperthyroidism, that has even
stage two to three early chronickidney disease those cats have
(03:57):
a shorter survival time.
So it didn't make sense thathyperthyroid cats would be
different just when they havehyperthyroidism.
So and this wasn't my clinicalimpression either so in this
study the goal really was tostudy a larger number of cats
and in this study we studiedover 1,000 cats followed from
(04:19):
the time they were diagnosed towhen they developed azotemia
between 6 to 12 months untilthey died.
So we looked at these cats overabout a 10-year period to try
to make sense of this and seewhat we found.
Sarah Wright (04:36):
Yeah, super interesting study and, I think,
very clinically applicable too.
So what are some of theimportant take-home messages
from this JAVMA article?
Mark Peterson (04:44):
Well, my clinical impression was right, if you
believe the study, because whenwe looked at our cats that
developed CKD or developedazotemia, defined as a
creatinine concentration greaterthan 2 at 6 to 12 months after
radiolidon treatment, theirsurvival time was one and a half
(05:09):
years shorter than those catsthat didn't become azotemic at
that time.
So survival time between thetwo groups was 4.3 years in the
cats that didn't developazotemia to 2.8 years in those
that did so.
This isn't to say that all catsthat become azotemic after we
(05:30):
treat them are going to dieimmediately and it's a terrible
thing to necessarily treat them.
They should be treated in somefashion.
But it's important that theowners realize this and the
veterinarians realize that theirsurvival time will be shorter
and that may influence how wemanage these cats and how we
treat them, what treatment we wechoose.
(05:52):
Maybe we don't want to treatall these cats with radio iodine
.
Maybe some of them should betreated medically or dietary
wise or something else.
Lisa Fortier (06:04):
Congratulations on a manuscript that's going to
change clinical practice.
Sometimes we do a lot ofstudies, but this one's really
going to move the needle, sothank you for sharing it with us
at JAVMA as well.
Mark Peterson (06:14):
Well, thank you for accepting it.
Lisa Fortier (06:18):
You're clearly a really good clinical educator.
I'm an equine orthopedicsurgeon, so the last time I
thought about the neuroendocrineaxis was a long time ago, and
even I understand what you'retalking about.
What sparked your interest inendocrinology?
Mark Peterson (06:33):
Well, you know, I went to school I graduated in
1976.
And you know, in veterinaryschool I loved endocrinology.
I liked diabetes and Cushing'sin dogs, for instance.
And so when I did an internshipand then a residency at the
Animal Medical Center in NewYork, and during my first year
(06:54):
residency I got involved in aclinical research project with a
physician studying canineCushing's disease and that was
very interesting and I for yearsI was probably one of the
world's top investigators forcanine Cushing's disease too.
But in 1979, we discovered ourfirst hyperthyroid cat and I was
(07:23):
lucky because of thisrelationship I had working with
this physician on canineCushing's disease.
I was doing endocrine roundswith physicians at the New York
Hospital Presbyterian in NewYork City.
So when we first had thishyperthyroid cat, I went to one
of the thyroidologists on roundsand I said we have this cat
(07:46):
with hyperthyroidism.
What do you think?
What should I do?
How should I work it up, whatwe should do?
And they were extremely helpfuland interested and I started a
collaboration with these guyswho were, you know, I couldn't
have done what we've done withhyperthyroidism without them.
So that's after once we startedhyperthyroidism, my interest in
(08:08):
Cushing's went way down andhyperthyroidism went way up.
Here's a new disease no oneknew nothing about and we were
seeing it.
The first year we saw about 10cats, and the next year we saw
about 100 cats, and the yearafter that it just kept going up
(08:28):
and up and up.
So you know, right now it's themost common endocrine disease
in cats and it's one of the mostcommon diseases we see in older
cats.
Cats are older than 10 years ofage.
One in 10 of those cats will behyperthyroid, so it's a very
important disease.
Lisa Fortier (08:49):
Fantastic, what a fabulous career.
It's so great to be aveterinarian and contribute and
collaborate with MDs and bringthat one health approach.
Yeah, move the needle on bothsides, mark.
Every time we do a study, likeSarah asked you earlier about
what some of the most importantfindings are, but we're always
surprised by something.
If you're really thinking aboutthe data, what surprised you
(09:10):
from this article?
Mark Peterson (09:14):
I think the biggest thing that I mean.
This happens every time I writean article like this where
we're dealing withhyperthyroidism and kidney
disease and that's how some ofthe cats that became azotemic I
would never have thought theywere.
You know there's, sometimesthere's.
You know, if you have a cathyperthyroid cat that's
(09:36):
untreated and has a creatininein the upper third of the
reference interval or has adilute specific gravity or has
polyuria or polygipsia PUPD, youknow you can suspect
hypothyroidism.
Some of these cats were notthat old, they had none of this
and they still went on to becomeazotemic.
(09:56):
So there's just not a perfectway to make the diagnosis until
we treat them.
It surprised me in this article, like it surprised me in the
past.
They're just not a good way.
But that said, looking at serumcreatinine, looking at BUN,
looking at specific gravity justthe things that all
(10:17):
practitioners can do and shoulddo that can be very, very
helpful.
And if you have a cat with alow specific gravity and the
creatinine is approaching thattwo limit, you know you have to
be very, very careful and thoseare the cats that we want to
really monitor very carefullyafter treatment.
Sarah Wright (10:35):
I think this episode is a good reminder to
clinicians.
Just to keep an open mind.
Don't take things off your listtoo early.
Always consider the wholeclinical picture.
Mark Peterson (10:43):
I agree.
Sarah Wright (10:46):
So what are the next steps for research in this
topic?
Mark Peterson (10:51):
Well, we're doing some studies now, or really are
done, that I'm writing up,where we're looking at not just
euthyroid cats but we're lookingat survival of cats with
hypothyroidism, becausehypothyroidism is relatively
common after we treat withradioidine.
And that muddles the picturebecause some of that azotemia
(11:13):
that can develop in hypothyroidcats can be pre-renal, because
hypothyroid cats have anincreased GFR, an increased
renal blood flow.
So once we treat thosehypothyroid cats they fall,
hopefully to normal.
But hypothyroid cats itcontinues to fall so they can
have a decreased renal bloodflow and a decreased gfr.
(11:37):
So that even makes the azotemialook worse than it really is
because of the pre-renalcomponent.
So I don't, we're looking we.
What we want to publish next isour findings, a long-term
follow-up of those cats, howthose cats can also become
azotemic and how treatment withthyroid hormone replacement can
(11:58):
help both their survival.
And I think in large partbecause we're helping with the
azotemia, because as we treatwith, as we supplement those
hypothyroid cats with LT4,thyroid hormone supplementation,
the azotemia gets better and itseems like the progression of
the CKD slows.
(12:18):
But those you know, that'sanother paper.
Sarah Wright (12:22):
Well, we look forward to hopefully receiving
more manuscripts from you.
Mark Peterson (12:27):
That's only, that's only the only job.
That's the only place I want togo.
Sarah Wright (12:32):
We're happy to hear that.
So this is.
The next question is somethingwe've been asking a lot of our
interviewees lately.
Just with the rise of differentemerging technologies and such,
do you see a role for AI inthis area of research?
Mark Peterson (12:46):
definitely, definitely, because there may be
something that I'm missing as aclinician that AI will help.
You know some absurd littlething in the serum chemistry
profile that I'm missing thatcould help us do it.
So I think we should look at it, and I say that being someone
(13:07):
who is kind of well, I wasreally very against AI, and now
I've been using it more and youknow, I'm I'm still, I'm always,
I'm always frightened about thefalse facts that can spit back
if you don't know what you'reasking.
Uh, but I've also found it tobe very, very helpful for me in
(13:29):
my work, so I'm excited to getmore and more involved with AI.
Sarah Wright (13:36):
Very cool and, for those of you just joining us,
we're discussing howhyperthyroid cats that develop
azotemia following successfulradioiodine treatment have
shorter survival times comparedto cats that remain non-azotemic
with our guest Mark.
Lisa Fortier (13:52):
Mark, what I've really enjoyed hearing you say
is how curious you've been ableto maintain, since you got your
veterinary degree and workedwith the MDs, just like thinking
, huh, that doesn't make sense.
How come that is?
And what about that?
How did all that combinedtraining help you keep that
(14:12):
curiosity and then get acrossthe finish line with all the
many, many manuscripts you'vewritten?
Mark Peterson (14:20):
I mean, I've always asked.
You know, when I was an intern,one of my staff members and I
won't mention his name becausehe may be embarrassed by this
but he told me once that I askedtoo many questions.
And he told me once I better doa residency and go on, because
(14:40):
maybe I should go to a vetschool and be an academic,
because all I did was askquestions.
And I've always asked questions, I've always been curious.
Lisa Fortier (14:52):
Did anybody call you Horshack?
Do you remember Horshack?
Mark Peterson (14:55):
No, but they probably should have.
So for me, the clinical, I meanI love, really, I love taking
care of hyperthyroid cats.
I really I love cats, right.
So that's fun for me.
But it's the clinical researchand learning and trying to get
(15:17):
to the next stage to help them.
I mean, when we discovered thisdisease in the late 70s, we
knew nothing.
We knew nothing.
We thought it was a raredisease that was going to go
away pretty soon and it'sbecoming a worldwide epidemic,
you know.
So there's so much more tolearn.
(15:38):
I thought my goal in my careerwas to try to figure out the
cause and and make the diseasego away, and that hasn't
happened.
In that regard, I failed, but Ialso have a lot of other people
helping me now, so hopefully wewill figure this out.
But it's, it's been fun, it'sbeen.
I've been doing this for 45years, doing the clinical
(16:00):
research on these cats, and it'sdon't know why I find it fun,
but I do, I really do.
I love what I do.
Lisa Fortier (16:11):
What's your gut instinct as to the cause?
I've been thinking about thatthis whole time.
Mark Peterson (16:18):
I don't think it's one thing First of all,
it's older age.
When we first, when, when themedian, when we, when we first I
wrote our first paper, uh, thein these cats and the average
age has always been about 12years, about age the 12 years at
(16:40):
that time was was an old cat.
We used to say look at this cat, he's 12 years and he's
hyperthyroid.
And people would come in andsay that's really an old cat.
Are you sure you want to treatthat old cat?
Well now, 12 years is not old,that's middle age.
So we did a study and between1983 and 1993 at the Animal
(17:04):
Medical Center, the reviewermade us do this work.
We did our whole hospitalpopulation.
You know, in the Animal MedicalCenter at that time we saw
about 100,000 pets a year.
So we had a lot of cats to lookat.
The average age of our hospitalpopulation in that 10-year
(17:25):
period went up by four years.
That's how much we've advancedveterinary medicine.
And that was in the 80s.
That's continued to happen.
So what's causing it?
Part of it is, I think catscould have always had this first
of all, but they just neverlive long enough, just like you
(17:45):
and I never used to get heartattacks because we would die or
be eaten by a lion in our family.
Right now, we live longer, sowe can die of some of these
other diseases.
That's one thing, but I don'tthink that's all um.
There's stuff in the, in the,you know, in in the 70s that's
when cat food was still startingto come out um, all these
(18:07):
synthetic compounds, theplasticizers, the bpa, all these
chemicals that are now soambiguous.
They were that they were, justthey weren't there before.
And we've shown that some ofthese um flame retardants that
tend to accumulate in dust.
We've done some studies, one ofwhich we put a collar around
(18:27):
the cat's neck and we didcontrol cats and hyperthyroid
cats, and the hyperthyroid catshad significantly higher flame
retardants exposure than theother cats.
So I think it's a combinationbetween their age, their
genetics.
Obviously there's something ingenetics because some breeds are
(18:48):
less likely to get hyperthyroidthan others, notably like the
Siamese and other Orientalbreeds.
So age, genetics, environmentwith the chemicals in the
environment and probably die.
You know, we've heard a lotabout these highly processed
compounds in food that are badfor us.
What about cat food?
(19:09):
The same thing is probably truethere.
People really haven't looked atit.
Lisa Fortier (19:15):
Well, thank you for sharing your insight.
Sarah Wright (19:19):
So, Mark, this next set of questions is going
to be very important for ourlisteners, and the first one is
dealing with the veterinarian'sperspective.
What is one piece ofinformation the veterinarian
should know about hyperthyroidcats that develop azotemia
following successful radioiodinetreatment?
Mark Peterson (19:37):
Well, you know, as I said before, if you have a
hyperthyroid cat that's alreadyazotemic, that cat has a.
Fairly the prognosis is notvery good.
If we treat them they generallylive less than two years.
So the prognosis isn't great.
But as long as they're notazotemic prior to treatment, as
(19:59):
long as that creatinineespecially if the creatinine is
less than 1.5 or less than 1.8,kind of in the mid to low range
and then they do become azotemic, this unmasking of the azotemic
chronic kidney disease isn'tnecessarily a death sentence.
Some of those cats live a longtime.
The median survival was 2.8years, so almost three years in
(20:22):
these cats.
So they can still live a longtime.
So why is it important to knowthis?
It's important to know itbecause we want to pick it up as
soon as we can so we can startto manage it.
So if they have chronic kidneydisease we may want to start
them and die.
There's other drugs to maybehelp kidney function improve, so
(20:43):
at least stabilize it.
But again, the important thingis that we can't predict very
well, at least right now, andthat's what AI may help.
But AI or not, I still thinkthere's going to be cases that
we're going to be surprised thatthis cat became azotamic, but
(21:03):
he did so.
Now we have to deal with it.
So close monitoring, earlyidentification, is really
important for that veterinarianto know.
You can't treat with radiowire,dine and forget the cat saying
well, he's got to be cured.
Now we have to look.
We want to monitor for threereasons.
We want to monitor for threereasons.
(21:24):
We want to monitor afterradiowire, as I tell my owners
and veterinarians we want tomake sure the T4 falls to normal
, the thyroid levels fall tonormal.
We want to make sure that thecreatinine and BUN stay normal
and don't start to go up,because if they start to go up
we have to address that.
(21:46):
And then, as I alluded toearlier, we also want to make
sure they're not becominghypothyroid.
So, to do that we always, forthe first year after we treat,
we always do a serum T4 and aserum thyroid stimulating
hormone concentration.
Because a high TSH or thyroidstimulating hormone
concentration is the best andeasiest way we can identify
(22:09):
hypothyroidism.
And if those cats becomehypothyroid then we want to
start treatment and that's goingto help the hypothyroidism.
It's always also going to helpprogression of their azotemia,
if they have it.
Sarah Wright (22:23):
Very well said.
So you kind of answered thisalready a little bit.
But what's one thing clientsshould know about this?
If you could boil it down tolike one important take-home
that clients should consider.
Mark Peterson (22:34):
Well, first of all, remember they have to be in
charge it's kind of like ofyour own health or your mother's
health and so forth.
So this is if their cat hasbeen treated with radioiodine,
they need to know that theirveterinarian may be a very good
(22:56):
veterinarian, but this could allslip through the tracks.
So they have to remember thatit's their responsibility to go
in, make the appointments formodulatory, make sure the right
tests are done, make sure thatthyroid function's looked at,
including the TSH, as we justtalked about, make sure that
renal function is addressed andlooked at.
(23:16):
And you know, in my practice,all the cats that we treat, we
encourage the veterinarians tosend me the results and I will
gladly interpret them and helpthem and advise them as we go
along.
They're not my—I considerthem—they're patient, but I
(23:38):
still would like to be involvedand probably know a little bit
more about this than many ofthem do.
So I like to still be involvedand help however I can.
Lisa Fortier (23:47):
That's very generous of you.
I've super enjoyed talking toyou and remembering some of
these things and just learninghow you've moved the needle so
much throughout your career, andthank you again for sharing
your information with JAVMA.
Mark Peterson (24:01):
Thank you for having me.
Lisa Fortier (24:03):
As we wind down, we like to ask a little more of
a personal question, and I'mgoing to guess yours is going to
be about a bird, given yourbackground.
What's your favorite animalfact?
Mark Peterson (24:14):
Well, it's about cats, of course.
Lisa Fortier (24:16):
Oh, of course, silly Lisa.
Mark Peterson (24:20):
So one thing that I like to tell people is the
way.
It's not widely known that catsand the way they communicate
with us, their owners, isdifferent than the way they
communicate with other cats.
When cats communicate withother cats, they do it through
their body language, their scent, they may have vocal cues, but
(24:44):
they don't normally meow atother cats, where my cats have
always meowed and screamed anddemanded stuff.
And this is something the catshave learned in their
interaction with humans.
So, the way they address us andspeak to us is learn from us.
It's not normally how theywould work with other cats.
They don't need to, they can.
(25:05):
They have their own, their ownways to do it through their
scent and body language and soforth.
So I again, like I, I justreally I love working with the
cats.
That's been, that's been that I, I just that's been made my
career and finding this diseaseearly on and spending my life
(25:25):
doing this has been very muchfun.
I've really enjoyed my career.
Lisa Fortier (25:30):
That's awesome.
Well, we compliment each otherwell, because I'm deathly afraid
of mean cats and it's one ofthe reasons I went into equine.
So they're all yours, buddy.
Mark Peterson (25:39):
Okay, well, you know something I've had a few
mean horses, and I'm glad thatsomeone's there to take care of
the horses too.
Sarah Wright (25:48):
Look at that, it goes both ways.
Yes, well, thank you so much,Mark.
Really appreciate you beinghere today and just sharing your
enthusiasm for this researchwith us.
Mark Peterson (25:57):
You're welcome.
Thank you very much again forhaving me.
Sarah Wright (26:00):
And to our listeners.
You can read Mark's article inJAVMA.
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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