Beneath the Surface: Toxoplasma and Immune-Mediated Skin Disease

In the April episode of Chattering with International Cat Care, host Yaiza Gómez-Mejías introduces two conversations that highlight just how complex feline diagnostics can be.

First, Dr Llibertat Real Sampietro discusses her JFMS Open Reports case study on fatal disseminated toxoplasmosis in an otherwise healthy cat. She outlines the parasite’s transmission, the clinical signs that may raise suspicion, and the value of serology and PCR in confirming infection.

Then, Dr Kelly St Denis is joined by Dr Frane Banovic to discuss the first of two JFMS Clinical Spotlight articles on immune-mediated skin disease in cats. Together, they explore how to recognise key patterns of disease and the practical role of cytology in reaching a diagnosis.

For further reading material please visit:

Fatal disseminated Toxoplasma gondii infection in a cat from Madrid, Spain

Frane Banovic : Feline Immune-mediated skin disorders (Part One)

Frane Banovic : Feline Immune-mediated skin disorders (Part Two)

View The Transcript Here

For iCatCare Veterinary Members, full recordings of each episode of the podcast are available for you to listen to at portal.icatcare.org. To become an iCatCare Veterinary Member, or find out more about our Cat Friendly schemes, visit icatcare.org

Host: 

Yaiza Gómez-Mejías, LdaVet MANZCVS (Medicine of Cats) CertAP (SAM-F) Acr AVEPA, Veterinary Community Co-ordinator

Speakers:

Llibertat Real Sampietro, DVM Acre AVEPA in Feline Medicine, Clínica Veterinaria Ayavet, Boadilla del Monte, Madrid, Spain

Kelly St. Denis, MSc, DVM, DABVP (Feline), Co-editor of the Journal of Feline Medicine and Surgery and JFMS Open Reports, St Denis Veterinary Professional Corporation, Powassan, Ontario, Canada

Frane Banovic, DVM, PhD, Diplomate ECVD, Associate Professor of Veterinary Dermatology in the Department for Small Animal Medicine and Surgery at the University of Georgia, College of Veterinary Medicine

Creators and Guests

Host

Yaiza Gomez-Mejias

Veterinary Community Co-ordinator @ International Cat Care

What is Chattering with iCatCare?

Welcome to Chattering With iCatCare, the official monthly podcast of International Cat Care, hosted by Yaiza Gomez-Mejias (Veterinary Community Co-ordinator). Each month, we chatter about cats and cat-friendly practices with industry experts and contributors to The Journal of Feline Medicine and Surgery. Each episode contains highlights from our longer discussions and interviews, which are accessible to iCatCare members at portal.icatcare.org. If you would like access to our full episodes, would like to become an iCatCare Veterinary Society Member, or find out more about our Cat-Friendly schemes, visit icatcare.org.

Hello, and welcome to the April episode
of Chattering with International Cat Care.

I'm Yaiza Gomez Mejias, iCatCare
veterinary community coordinator

and host of this month's podcast.

Our clinical spotlight this
month is focused on dermatology.

Dr Kelly St Denis will be speaking
with Dr Banovic about immune-mediated

skin disease in cats, it's
presentation, diagnosis and management.

But first, I will be interviewing
Dr Llibertat Real Sampietro on

her JFMS Open report about fatal
disseminated toxoplasmosis.

What is toxoplasmosis and
how does it affect cats?

Toxoplasmosis is a disease caused
by Toxoplasma gondii, which is

an apicomplexan proteasome, and
it has a worldwide distribution.

Cats are pivotal in Toxoplasma persisting
in the environment because they are

the only mammal or the only being where
Toxoplasma can sexually reproduce and

so how it affects cats is usually it
doesn't affect them at all actually.

And then sometimes in some cats, it
can cause disease, which can range

from mild to acute fatal disease.

So we can have a wide range of
presentations, but most of the time

we will have no disease at all because
the relationship between toxoplasma

and cats, and cats brains, which we can
speak about later, it's very ancient.

It's very old, and so they
have adapted very well.

It will usually not cause
any disease in cats.

How do cats catch the disease?

Cats can catch the disease by mostly
two ways, but there's a third one also.

But basically they will catch it by
hunting small prey, that can be rodents

or birds, because toxoplasma can live
in any warm blooded living being.

But also if humans feed raw meat
to cats, they can also catch it.

And also sometimes they can
become infected by their mom when

they're in womb by their mom, and
sometimes also through the milk.

What are the typical signs of fatal
disseminated toxoplasmosis in cats?

We should suspect it when a cat becomes
very ill, showing severe disease after

exploring the cat and running the
blood test, or the imaging test that

we need to run, the disease mostly
appears focused on the respiratory tract

and liver, but also on the pancreas.

Other cats may present with
acute neurological disease.

This would be the other way of presenting,
but when it is acutely disseminated,

usually it's not only the central
nervous system that is affected, but

also the liver and respiratory tract.

The clinical science may come across
as nonspecific, and on top of that,

we have a rapid deterioration.

So it's all quite challenging.

And also none very specific, but at the
same time a bit strange because you don't

tend to see many cats with respiratory
and liver clinical signs and biochemical

changes and it progresses really quick.

So the first day you may think it's
pancreatitis, or maybe I just have

a cat with some degree of pneumonia
and he's very ill because of the

pneumonia, but then because of this
very rapid progression, then you see

that the liver goes really worse or the
pancreatic disease will go really worse.

But at the same time, you get all
those respiratory changes and that

doesn't make much sense with either
liver or pancreatic disease by itself,

not being by an infectious disease,
so that makes you think about it more.

I think we should think about it when it
goes quick and affects these two organs.

If they have ocular signs or central
nervous system signs, that should put

it from the differential list higher.

It can be tricky, can't it?

How do you diagnose toxoplasmosis In cats?

You need clinical signs compatible with
the disease for one thing, because you can

have many cats that have become exposed to
the toxoplasma because they ate that prey

or that raw meat that had the cysts there,
and then they contacted the parasite.

It became disseminated and it
became dormant and nothing happened.

But because the big contact, the
parasite, they will have produced

some sort of immune reaction to
it, and because many cats become

exposed, you can have many cats being
positive to toxoplasma not being ill.

So you need to have compatible clinical
signs, or at least some sort of clinical

sign that you could put into toxoplasmas
list of things that can cause, and then

you need to prove the parasite is there.

You can prove it with serology sometimes.

With serology, you can do, you run
immunoglobulins and you need to run

IgGs and IgMs and you need to run both
of them because IgGs will only show

that the cat has been exposed to it.

So you can have a very high titre
in a completely healthy cat.

Pregnant women can have the
toxoplasma test and be healthy.

Or it can be negative if it's been
a recent exposure, but, and then you

need to run the IgMs, and the IgM,
it will show recent exposure and it

will indicate an active infection.

So, if your IgM titre is positive and is
above 164, then that means that cat was

exposed, recently exposed to toxoplasma.

So if you get that positive titre
and he shows clinical signs compatible

with it, that could mean it does
have toxoplasma, but you could also

have a healthy cat with a positive
IgM just because he was recently

exposed, and it would only mean that.

So as with all diseases, we only
need to look when we have clinical

signs compatible with the disease.

And if you find some lesion or some
area where you think it's focused,

your disease, for instance, in our
case it was the lung and the liver,

but you could have skin nodules, or
you could have cholecystitis and a

bile infection, enlarged abdominal
lymph node, pneumonia, you could do

a bronchoalveolar lavage as well.

When you have localised where your
problem is, if it's a place where you

could take a sample with a fine needle
aspirate or with pathology, you could

run a PCR and if it was positive, that
would show that the parasite it is there.

And now Dr Kelly St Denis will
be interviewing Dr Banovic

about his JFMS article on immune
mediated skin disease in cats.

This is the first of two parts,
and you will be able to access the

second part of the interview in June.

Today we are meeting with Dr
Frane Banovich, to discuss the

clinical spotlight articles that
he's written for the Journal of

Feline Medicine and Surgery, feline
Immune Mediated Skin Disorders.

There are so many immune mediated
skin disorders in cats, that

we decided to break it into two
different clinical spotlight articles.

From a general perspective, Dr Banovic,
I was wondering if you could just

discuss with us like how common are
immune mediated diseases in cats?

Very good question.

So in general rule, there is always debate
about using terminology of autoimmune

and immune mediated as disease processes.

In general sense, we prefer to use
autoimmune when we can really show

that there is a direct immune response
against its own tissue, against its own

antigen, which we would call auto antigen.

Unfortunately, in veterinary
diseases or veterinary medicine,

the advancements of techniques
generally lacks the human field.

So in many instances we have a high
suspicion that there is an auto antigen,

but we generally lack techniques or
studies to prove that so many times

the, we like to use the terminology
immune mediated diseases, which shows

that there is an inflammatory process.

Highly likely it's autoimmune in many of
these cases, but unfortunately, due to the

lack of studies, we cannot really come and
say, oh, this is an autoimmune disease.

We show that this is an auto antigen,
and if you look at the dogs and cats,

we have far more evidence in dogs
than we would have in cats because

in general sense, I would also say
as a clinician scientist, we tend to

research less cats than we do dogs.

That's so true.

And also, to be honest, I would also say
that it's not as easy to collect samples

from cats as it is from dogs, which
also contributes to the problem I think.

Now, regarding these diseases, how
common they are, it's a very good point.

I would say that in my clinic, the most
common disease we tend to see is some kind

of an allergic dermatitis disease, whether
that's a feline atopic skin syndrome

or atopic skin syndrome due to food.

I would say that's rare.

And then we do see these weird
immune mediated diseases come

to us on a regular basis.

Some of them come through ER because
the cats have undiagnosed pemphigus

that is not an allergic skin
disease, but gets treated like that.

And then they unfortunately come
through emergency service because

the patient is not doing well.

Some diseases are not that dramatic
and it's just a foot pad and

therefore can wait a month or
two months to get a referral in.

So it just depends on a patient.

But do we see them?

Absolutely.

Yes.

As a matter of fact, to give you a fun
story, one of my PhD students last week

emailed me foot pad lesions from her
roommate's cat, and the cat has a, what

we would call plasma cell pododermatitis.

It's in, in the part two, but
classic example of it, all four

feet, all four central pads.

And of course, so they do, they are
there, but maybe they are not diagnosed.

Maybe sometimes they're, there's
not such morbidity that people

are gonna investigate more in
depth and multiple factors.

Yeah.

Yeah.

And so as clinicians, like someone
for myself in general practice,

obviously there's some pretty classic
things that we may see that say immune

mediated derma dermatologic issues
or autoimmune dermatologic issues.

But when I'm looking at a cat with
skin disease, would you say there's

a short list of things you would
say, we should put that autoimmune

disease on our differential list
as soon as possible, or right away?

There are some clues like in the paper.

That is the reason why we decided
to go into the paper project because

some diseases definitely have a very
relatively unique clinical phenotype.

So, for  pemphigus that would be, for
instance, there are not many diseases

that will cause very uniquely the
nail fold production of puss in there

and when you squeeze the nail folds
out, you basically see pus coming out.

That's very unique for pemphigus
foliaceus in cats, there are not

many differentials that will do that.

Same thing with, for instance,
plasma cell pododermatitis.

Very unique to affect the central foot
pads of multiple legs, so there are

not many diseases that will do that.

So they do have some uniqueness sometimes.

It may be a little bit tricky, but if
the patient is not responding after

multiple weeks of treatment, whatever
the clinician thinks, it is advisable

to obtain good quality images and
consult with a veterinary dermatologist.

I was wondering about diagnosis because
this is something that with Pemphigus,

they used to always tell us, and again,
I'm dating myself here in terms of

when I graduated from vet college, but
it was always about waiting for the

pustules and only biopsying pustules.

But I really like in this article
that you guys discuss cytology that

can be done and it isn't always
just about sampling from pustules.

And I wondered if you could tell
us a little bit about that from a

practical perspective in clinic?

Absolutely.

So there is a little bit of debate even
among the dermatologists here, how we

should approach this largely because we
are dermatologists, so we just see the

skin cases and for us to diagnose our cat
with pemphigus is to some point, if we see

these cases all the time, relatively easy.

The problem becomes is that we have
to provide advice to clinicians who

are not dermatologists, that they
get to see all the organs and all

the diseases associated with that.

So in these instances, we are always
troubled how to make a recommendation.

Why do I say this?

We utilise skin cytology a lot to
diagnose pemphigus because we can see

the Acantholytic keratinocytes, which are
very unique for the disease and with the

clinical presentation of the nasal bridge
and the ear pinna and the nail fold.

We generally don't tend to see
many differentials for that, such

as potentially like a pyoderma
staph [ylococcus] infections with

exfoliative toxins that can also
cause Acantholytic keratinocytes.

We rarely see that presentation
of pyoderma in cats.

So therefore, when we see a patient
like that, and if you do a cytology

and we can see this Acantholytic
keratinocytes surrounded by neutrophils,

we are very much probably, I would say
above 99% certain that we are dealing

with pemphigus foliaceus in a cat.

Now, ideally we would go ahead
and biopsy that, but then it

depends where the lesions are.

And for instance, some lesions,
some cats with pemphigus uniquely

have only lesions in the nail fold.

So there are different
phenotypes of the disease.

Not everyone is generalised.

So in that case, you will have to
remove the whole toe and that's

where it gets a bit tricky.

I would say that the vast majority of
us tends to then call the Pemphigus

based on a clinical presentation,
history and cytology findings.

Of course, if we can, we
will go ahead and do biopsy.

Now we are dermatologists, so for us,
this is what we do every day of the month.

Now, if we take someone who sees this
rarely as a private practitioner,

they may lean more towards biopsy to
make sure that we get what we need.

Yes, ideally we would sample pustules,
but they are relatively short lived on

the patient's dogs and cats predominantly
because of the rather thinner

epidermis, so they don't tend to stay.

So what you end up
having is usually crusts.

Now, if you see some erythema
beneath, it tells you that probably

it's still an active process.

So we tend to go and try to get
those most recent lesions that

the owner can remember and that we
see that there is still erythema.

If the crust has no erythema
and you can just pull it off,

then likely it's already gone.

What we never wanna do
is scrub the crusts away.

So we always wanna submit the crust
because the are acantholytic keratinocytes

are usually embedded in them.

If you do any surgical scrubbing,
you will lose that diagnostic sample

and your biopsy will come back as
inconclusive, meaning they don't know

what, it's an inflammatory process, but
they don't know exactly what's going on.

And that's one of the key things that
again, are pointed out in a box out

in your article about taking biopsies
and not prepping the skin or shaving

or anything because you're taking away
a lot of that diagnostic information.

You rarely will ever need to scrub
the skin, exceptionally rarely.

So I would rather not to do
that on, on any patient unless

you want lose your diagnostics
and the biopsies are expensive.

You need a heavier sedation
for a cat than a dog.

Therefore, you do not wanna repeat
these processes multiple times.

So it's better when you do it that
you do it the best way you can.

Thank you for listening.

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If you’re looking for more free CPD
from International Cat Care, on the

6th of May Rachel Korman will host
an open webinar sponsored by Hills.

She will talk about the new guidelines
on lower urinary tract disease in cats.

On the 21st of May, Dr Stephanie Sorell
will talk about diabetic ketosis in

the feline patient in another open
access webinar sponsored by IDEXX.

We will be back again next
month with more from the world

of feline medicine and JFMS.