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.
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.
If you are an iCatCare Veterinary Society Member, don’t forget you can access
the full version of the podcast and all the other member benefits, including
congress recordings, monthly webinars, the clinical clubs, the discussion forum
and much more at portal.icatcare.org.
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.