Hello everyone, it's Anthony Chadwick from the webinar vets, just welcoming you to another one of our expertise courses this time on my favourite subject, which is dermatology, and tonight we're gonna be talking about differential diagnosis of nasal dermatitis. It's a really interesting area and I'm, I'm sure Hillary's gonna, really, present really well on this. It's such an interesting area.

Hillary is based in Glasgow. At a referral centre there, but also teachers at Edinburgh University, where she's was a long time with Richard Halliwell, where she did her diploma in the American College of Veterinary Dermatology. She then also spent time in North Carolina State, she was there for, for almost a decade.

So massively experienced in dermatology, obviously a diplomat. Of the British as well as the American College. I'm really looking forward to the webinar.

I'm sure I'm gonna learn a lot and, over to you, Hillary. Well thank you very much, Anthony, and welcome to everybody this evening. Tonight we're going to look at noses, and we're going to, I want you to have a really good look at noses, because you can tell a lot by looking at the skin.

So we're just gonna go through, a little bit about what we're going to do. We're just gonna look at the nose first of all, a normal nose, have a look at the normal nasal anatomy, and then we're going to look at a problem oriented approach to nasal disease. And I'm going to touch on.

Well, specific diagnosis but management, I don't have within the scope of the time here, a lot to talk about management of specific diseases, but if you've got any questions afterwards, I'd be happy to answer those. So first of all, let's have a look at the nose. Now, the important thing about the nose is, it's obvious, it's not the head skin.

The margins of the nose, we do consider as a mucuscutaneous junction. And if you can see from both these pictures, particularly the one on the right, that the nose has a normal cobblestone appearance, and that's really important. When we come to have a look at pathology of the nose, because you really want to have a look at whether it retains its normal appearance, whether you've got changes in pigmentation, whether we've got ulceration, erosions, crusting, we're gonna go through all of those.

The picture on the left obviously is a more brachycephalic dog. They have problems obviously with . Airway syndrome, but, and you can also get some degree of a nasal folding, a nasal disease, but actually for the purpose of this lecture we're going to look specifically at the nasal planum.

But do notice on the left hand side, the nasal filtrum, that's an important structure that we're going to have a look at for some of one disease in particular as well. The nose is normally fairly moist, whether it's dry, moist, doesn't really pertain to the animal's health, but there are some conditions that we're going to have a look at where it may get particularly dry and require some treatment there, and it is innervated by the nasal glands are innervated by the parasympathetic system. And they do, provide some moisture for the nose.

So let's go and have a look at some diseases. Now I want you to have a particular look at this series of noses, and all of these have slightly different diseases. So the, the shelter that we're looking up up here, you can see there is some alopecia.

You've got some deep pigmentation of the nose, and if you have a look along this area here, you've actually got loss of the architecture as well. So to me, looking at this, you've got, this is actually sick atrial alopecia where you've got scarring and loss of the architecture means to me that you've got something that has actually destroyed the basement membrane or in infiltrated the nasal planum. Contrast that with this nose on the, the right hand here, where you've actually got hyperplasia and fronding on the top of the nose.

So something has distor disturbed the normal architecture of the nose. The cornification process has been disturbed and you're actually getting excessive cornification developing. Down here we've got some ulceration, but it's a specific pattern of ulceration, ulceration of the nasal philtre and two small areas in the ala folds up here, whereas the ulceration on this nose is on the AA folds and extending up the bridge of the nose.

And then I want you to look at this nose where we've got retained the cobblestone architecture. But if you look at the left hand side of the nose as we look at it, it's reasonably normal and all the pathology on the right hand side. So when I see a case, I'm actually sitting, doing my history with the .

The owner, but I'm actually looking specifically to see, can I see a pattern of disease when I'm looking at this skin and specifically at this nose. Oh sorry, there's a Westie just joined in here. You see this Westie's got a fairly normal nose on the top and some infiltration, causing some depigmentation on the bottom.

So we're going to come back to all these cases during the lecture, but I would just want you to have a look at this slide and say, well, all those diseases aren't made equal. By looking carefully at these, we can refine our differential diagnosis, and make a specific diagnostic plan for these animals and treatment plan as well. So we're gonna start at looking at crusty noses.

And the first question I was we're gonna have a look at is this hereditary nasal hyperkeratosis that's been described in Labrador retrievers. It is reasonably common. And these usually present, when they're 6 months onwards.

Often it gets worse when they're 1 to 2 years of age. It has been characterised and it has been shown to be a monogenetic autosomal recessive disease, and you can test for this. There is a, a genetic test that you can perform, labialin.

In the UK, will do this test for you. It's a miss sense mutation in this gene, which encodes for histone, and his stones are fairly ubiquitous, but it's thought to be important in the normal keratinization and formation of the cornified layer. So, there's not much we can do about correcting the defects presently, but certainly regarding management, there, there are things we can consider.

And I'm going to consider that when we just after this one, which is the idiopathic nasal hyperkeratosis, which is more commonly seen in older dogs. Sometimes brachycephalic dogs. We don't know what the aetiology is here.

It's possible that it may be, genetic mutation which just has a target of onset, we don't know. But they, for both these diseases, They can develop painful fissures and secondary infections as a result of the disordered cornification that occurs on the nasal planum. And so it's important that we address and try and manage that aspect of the disease.

Now, traditionally we've used petrolatum derivatives such as Vaseline, or you can use lanolin lanolin or beeswax. What you're doing here is you're actually just putting some a fatty layer or an occlusive layer on the top of the nasal planum or the skin if you're using it there and you're preventing trans transepidermal water loss. So you get an immediate improvement.

You can also use polyethylene glycol topically, and that's a humectant. What that does is it actually draws up, the moisture from the underlying dermis into the epidermis. And these will, as I say, will prevent immediate, they'll cause an immediate improvement.

And the appearance of the nose, and they can be used as long-term, long-term treatments. A more, In modern day approach, however, is to actually use essential fatty acids and substances such as spitosinoscenes, which are serumides, which are the important part of the epidermal barrier, and you can replace those, and it's a more physiological way of repairing that damaged nasop plannum or skin, if we're using it there. And I want to illustrate, just mention to you this study that was done, and it was placebo controlled, a blinded study in 39 dogs with the idiopathic nasal hyperkeratosis, and it was done over a two month period, and it was using a spot on that you may be familiar with called Dermacent biobalm.

Now, I do believe that you can use the Allodem spot on in the same fashion. And you would just apply it daily to the affected area, a few drops on the nose, and they did demonstrate significant improvement in the clinical signs in treated dogs, and it's easy to do and no not many side effects and the owners for the most part were very pleased with the results in this study. So something to consider for those crusty noses that you see from time to time in practise, which may bother the owner more than the dog, but as I say, once they get to the point of fissuring and secondary infection, then they can be quite disturbing and uncomfortable for the affected animal.

Right, so moving on, this is a less common disease but one perhaps you might have seen, although you might not have, have recognised it, and that is the so-called parasympathetic nose or serum icteria. And the cause of this is damage to the parasymptic fibres of the facial nerve, and this causes sometimes a neurogenic KCS, which can be either bilateral or ipsilateral. And you'll sometimes get the KCS in conjunction with crossing on the nasal planum, or you may get it as a unilateral problem or just affecting the nasal planum.

And this is the dog I showed you earlier, which had a normal nose on one side, and then you've got some crusting and secondary ulceration on the ipsilateral side. Now, the cause of this, as I said, is the, if you look at the, the facial nerve, you've got the branches coming up of, to the glands surrounding, supplying the eye, and then you've also got these glands coming down to the nasal glands as well. So if you've got damage to this nerve anyway, anywhere along the path.

Then you can actually get interruption to the glands supplying the nose or the eye, and this drying effect. The treatment, would be anti-inflammatory to reduce the inflammation around the nerve. Sometimes it's permanent damage, sometimes you can get a nervous, regeneration, and, .

If, if it's permanent, then you can use ocular pylocarine, a few drops in the, in the eye, and that will travel down and the nasallaal gland and stimulate production of the nasallaal secretion. It's usual to start at a low dose and just titrate the polycarpine up, slowly. Moving on, is the zinc responsive dermatosis, the more common one that I see is type one, and this is seen in Nordic breeds, and it's thought that the Nordic breeds have a defective absorption or utilisation of zinc.

Now, bear in mind that zinc is a fairly ubiquitous element, so most dogs, almost all dogs will actually be absorbing adequate zinc from their diet. . We do, I do occasionally see, much less now, but, type 2, where dogs are on poor diets or they may be on supplements, and the poor diets are usually fairly heavy in yates cereals which produce yates which bind the zinc and and make the zinc less available for absorption.

So the type 2 disease is usually corrected by correcting the diet. The type 1 disease in the Nordic breeds, is usually the one that where we would need to treat because these animals can't absorb or utilise enough zinc. So here's an example of a dog.

This is Kobe. Kobe has a fairly characteristic clinical presentation. It's affecting his, sorry, that's not a very good picture, but this is his portion of his nose where you've got the crusting, it can lead to fissuring and ulceration.

It's not uncommon to get other areas affected like around the other mucuscutaneous junctions like the lips, periorbital skin. And, for him there was periggenital, crusting as well, so he's some crusting on the scrotum. The diagnosis, would rely on the breed, the clinical presentation.

It's, I'm often asked whether, it's, appropriate to serum zinc levels. Unfortunately not. You can get that test done, but bear in mind that zinc is ubiquitous.

And if you're going to run a zinc sample, then you need to collect samples into proper tubes because zinc can be absorbed from the glass in your serum sample. . But we wouldn't advocate, generally doing serum zinc levels to make a diagnosis of this, really requires a skin biopsy.

We do get a fairly characteristic pattern, and just for those of you not familiar with or have not familiar nowadays with looking at skin biopsies. What we're looking for is this disorder. This is the crust that you can see clinically.

And actually this is an abnormal qualification process where you get, what we call a mela parakeratosis, and that which is one of the, the markers for this condition. And it can occur in other conditions as well, but certainly if I was to see that on a skin biopsy in context of the clinical case that I've just showed you, then I'd be comfortable making a diagnosis of a zinc responsive dermatosis. How do we treat it?

Well, it's important to correct the diet. And I would certainly say that if you've got a dog nowadays that's on one of these, raw diets or homemade diets, then, putting them on a, a good balanced diet is, would be quite important. And it's also, in addition to the zinc supplementation, it's also important to add in essential fatty acids because there's there is a lot of synergy between zinc metabolism and essential fatty acid metabolism.

So I'll just add something that's got balanced with N6 and N3 fatty acids. The zinc supplementation, you need to be careful here. Some of the products that are marketed for supplements and may not have enough zinc in them.

They might have biotin, they might have zinc, they might have some vitamin A in it just market it as a general zinc supplement, sorry, skin supplement. That's not going to have enough zinc in it. You need to actually get a specific formulation of zinc, of which there are a number, and I usually send my clients down to Holland and Barrett or another herbal food store and ask them to buy the zinc supplements that are marketed for humans.

Now, the amount of zinc that you're going to supplement depends on the bio bioavailability of the zinc, and these are listed in the formulary and it's going to depend on the zinc supplement itself. So you can use zinclothionine, you can see zinc gluconate. I would, tend not to use zinc sulphate, not there's anything wrong with that, but it does tend to make dogs vomit.

And you would need to Correct the diet as you zinc and essential fatty acids, and you do usually get a reasonably quick response. So I'd expect some improvement within 4 to 8 weeks. Remember to treat any secondary infections.

These are often present with pruritus, and the pruritus is usually due to the secondary bacterial or mala malacisia colonisation which can occur in these cases. As a note, certainly I've had some cases, where we've had to require anti-inflammatory doses of prednisolone on top of the zinc supplementation, its central fatty acids to control the dog adequately. But I would certainly start by with the zinc supplementation, the scent fatty acids in the diet, for a couple of months before I'd add the, the prednisolone in.

And this is a lifelong treatment for these Nordic breeds because it is a lifelong condition. OK, so I've I've included panhigus folia in the crusty nose section, although this is primarily a pustuar disease, but most of the time, by the time we see it, you are seeing the secondary crust because the epidermis, dog epidermis is so thin that these musculars rupture. So this would be a characteristic, clinical presentation.

Now note that, most autoimmune diseases of the skin will present in a symmetrical format. So you've got the skin of the nasal planum and the head skin affected in these dogs, and some periorbital, it doesn't affect the mucuscutaneous junction, but it's the periorbital skin that's affected. Ephigus folio can be heterogeneous, it can vary in its distribution and certainly we do see cases where the disease is generalised, but this would be very characteristic of the facial disease, that we see.

When I say it generalises it can affect the foot pads, so you've got some pustules developing on the margins of the foot pad here, which can be very, very painful. The pinna are often affected, affecting the convex and the con concave surface. And this is an example of the primary pustule associated with this disease.

Here's a Doberman just with the purely with the, head, skin, and the nasal planum affected. Now, if you look at that carefully, can you see how you've got multifocal crusts? So I'm looking at that and saying, well, this is actually a multifocal disease because the crusts are very discrete rather than some of the crusts that I was showing you earlier.

Does affect cats as well. So here's a cat with the nose affected and in cats, you can also get the penny affected and particular to cats, it can affect the foot pads, but also you can get the nail folds affected and here's a pustule that's ruptured in the nail fold, quite a painful condition for the cat, but it's causing some erosion in that area. So these are sterile pustules.

It's an autoimmune disease which where the autoantibody is actually directed at the adhesion between the the carrainnocytes, and my former colleague in North Carolina has done a lot of work in this and shown that at least the . Antibody the antigen in dogs is deser coen in most cases, but what you see is free floating caratincytes. This is the low power and these are the carratinocytes that have broken away from the epidermis.

You can see some of them are still joined together in rafts. And the whole process attracts neutrophils to the area, and these tend to be intact neutrophils, and if you were to culture this, in the primary state, it would be a sterile, disease as well. And definitive diagnosis would be with a skin biopsy.

In the cases I've shown you, I would take a punch biopsy just over over one of those crusts that you can see, and you get a subcorneal pustule and you can see quite nicely here the caratnocytes breaking away from the epidermis and the neutrophils in this intact pustule. And that would be diagnostic of Penthigus foliacious. Now pemphigus foliacious can be drug-induced.

It's very well characterised now that it can be induced by some spot on preparations. In those cases, the disease usually starts at the site of the spot on, and then it can generalise. It can also be a pemphigus-like disease can also be caused by some.

Epidermotrophic dermatophytes, such as trichophyton. So just to bear that in mind, and you'd probably want to do a fungal culture just to rule out dermatophytes before you embark on immunosuppress therapy for these animals. I'm not going to talk at great length about management because I see a lot of encus in my practise and I don't find it particularly easy disease to manage.

I do find the response is very variable. The younger the dog is, the better they do respond. But the mainstay of treatment would be immunoexpressive doses of prednisolone, but we often have to add in other immunoexpressive agents as well.

And such as cyclosporin, lorabaci, azathioprine or mycophenolate. None of these, down here will work particularly well by themselves, but you, they're often used as, steroid sparing agents. Right, now I'm going to move on to talk about ulcerated noses.

And I don't know how many of you have seen this disease. This is an interesting one. It's dermal arthritis of the nasop planum, and that is where the deep artery supplying the nasop plannum right in the iltrum here deep deep to the iltrum becomes inflamed.

It's thought to be an imm immune mediated condition, and these dogs present with really spectacular epistaxis, and they really do bleed. It was first described in the nasal filtering of a giant schnauzer and St. Bernard's.

Here's another example over here. But it's since been described in Basset, Newfoundland, German short haired pointer, and, but anecdotally, I believe it's been seen in German shepherd dogs. I've certainly seen one in German shepherd dog and in the Nordic countries they see it in German shepherd dogs as well.

So these dogs have recurrent haemorrhage, which is often quite spectacular. And this is the characteristic of the pattern. So you've got the main artery affecting the nose and the filtrum affected, but it's not uncommon to get these, we think there's secondary branches, so you get these little fissures up in this area.

You rarely see these, you won't see these by themselves, but the appearance of these fissures along with this ulceration and haemorrhage occurring from this area would be fairly characteristic. You can, the definitive diagnosis would be to biopsy these and, demonstrate that you've actually got inflammation of the main artery, but you may be a little bit brave to biopsy something that's really bleeding very badly. The treatments, systemic topical steroids, .

Systemic or topical steroids, sorry, have been a treatment. A recent publication and anecdotally, I believe that using to tacrolimus, which is a calcium urine inhibitor related to cyclosporin, if you just plaster that on the affected area, that seems to be very effective. And there certainly has been a surgical technique, described, for those refractory cases which won't respond to immunosuppressive treatment.

OK. Probably a more common disease causing erosions and ulceration would be the mucuscutaneous pyoderma. As I said, this is a mucuscuaneous junction.

You often get a bit of erosion and ulceration and some crusting around this area. Other areas that can be affected are, around the eyelids, the lips, and sometimes the periggenital areas as well. It's another example, affecting the junction between the nasal platum and the head skin.

Now cytology from this, on the right hand side, we use cytology a lot and you can demonstrate there are a lot of bacteria there, so we can see cockeye colonising in the area. Now, we could argue that this may be a primary. Erosive or ulcer disease which has been colonised secondarily with bacteria and that's entirely possible.

But the only way that you would differentiate between these primary autoimmune or immune disease and muchapierma would be to treat with antibacterial agents until you've got negative cytology. And see whether the lesion is completely resolved. Now, in a mucuscutaneous pitoderma, you should get complete resolution with antibacterial treatment, whereas its secondly colonisation of an underlying disease, then you may only see partial resolution.

I'm going to discuss that in a little bit more detail in a minute. Certainly, to treat something localised like that, I would probably use, try and use something like topical sidic acid, . You not fusidderm, but you could use fusidine, which is just the fusidic acid component.

You could use lorhexidine wipes or something like the Duoopyo foam. Just to, to, treat a localised lesion like that. Now, this is And important area for discussion, I think, and that is how do we differentiate between the mucuscuinus pyoderma and cutaneous lupus, which is affecting the nose, and certainly it's an area for debate within the dermatology community as well, because they both look very similar on clinical presentation.

And as I've already indicated, one of the differentiating features would be whether it completely resolved cytologically and clinically just with antibacterial treatment. So let's ask the question, well, what is lupus? Well, the definition of that is a chronic inflammatory autoimmune disease, which may affect many organ systems, and you're probably familiar with SLE, which is in fact quite an uncommon disease.

More commonly we see cutaneous lupus syndromes which affect only the skin. And to make a diagnosis of lupus in the skin contains lupus, then we need to demonstrate some lupus-specific histopathology. And this is an interface dermatitis where you've got damage to the basement membrane and some lymphocyte infiltration and these apoptotic cells at the dermo epidermal junction.

Canine lupus diseases, which have cutaneous involvement, there are a number of them, they're very uncommon, but for the purpose of this, this discussion, we're looking at discoid lupus and nutricutaneous lupus. Now human discoid lupus erythematosis, you need to demonstrate these interface changes, some superficial and deep dermatitis and some thickening of the basal membrane, and in people it affects the the nasop planum. It can affect the hands and the face, and it is a scarring disease in people and here would be an example of canine discard lupus where you've actually got, oh sorry.

You do have some ulceration around the epidermal junction, but you see how you've actually got some nonhead, the head skin involved as well, but it's actually quite s psychiatricial. You can see it's actually affecting scarring and shrinking down, so this dog is not gonna have a depigmented nose in the long term. So that's an example of the canine disease, which is fairly similar to the human disease so the.

Now that's to be differentiated from canine nasal dermatitis, and I'm, I'm putting this up for discussion because the traditionally there have been a lot of nasal diseases which have been called lupus. And in fact, they, they're not actually lupus at all. At the histopathology from a normal nasop planum or even an inflamed nasoplanum, you will see a lot of plasmacytic and lymphocytes there because it is a mucuscutaneous junction.

What we haven't got is the apoptosis and the lymphocyte infiltration across the dermal epidermal junction. So you cannot call this lupus. It's just dermatitis of the nose.

And there was an interesting study done back in 2002 where this French group looked at the 15 dogs who'd actually been diagnosed with discoid leuko erythematosis of the nose. And when they reviewed the clinical signs and the histopathology, they only found that 7 of those 15 dogs actually had the true disease. So I think it's really important that if we are going to biopsy and and look at nasal diseases where we suspect lupus that we need to be very careful in fact what we are actually diagnosing.

So what about more recent publications? Well, this is a study that was done by my former colleague in North Carolina where they looked at microcutaneous lupus erythematti in dogs, and these were predominantly German shepherd dogs. They are 21 cases, and these dogs had, as you can see, some erosions and ulcerations around the nasop planum, around the Ala area, .

Here, on, on the nose here, but they also usually had some lesions in the other mutaneous junctions around the lips, the peroneal area, periggenital areas as well. And what they found, was that the they made a diagnosis based on these because they could see the lupus specific pathology, but what was interesting is that they found that bacteria who are commonly involved in the disease, but when they treated the bacterial infections, that the lupus disease did not completely resolve, so they had no partial response to antibacterial therapy. And the, after the antibacterial therapy was stopped, then the dogs did respond to immunomodulation of some description, whether it be prednisolone or other immunosuppressive agents.

But it was really important to continue with topical antimicrobial treatment. And it's Felt, and I feel that this disease and the German shepherd dog, cause we do see it from time to time. We do wonder whether the bacteria that are involved in this condition actually play a role in stimulating the lupus type reaction.

So it may be a combined or or an immune-mediated disease of the skin which is actually triggered in the first place by bacteria, because as soon as the bacteria are there, it certainly does seem to make the disease a lot worse than you would expect with just secondary bacterial colonisation. So the important take home message from that is if you do see lesions like that. Do cytology, if there's bacteria present, treat with antimicrobials first.

If there are still erosions or ulcerations after you've got cytological normality and no bacteria present, then that's the time to do your biopsy, and I would send these biopsies to a pathologist who's practised at looking at skin because these can be quite subtle lesions to to diagnose. OK. Now, we're going to move on to look at some cats.

You know, mosquitoes are not common in Scotland where I live, but we do see midge bite hypersensitivities. These are cats that are outdoor cats, and they like to go. Out in the dawn and dusk, when you've got a lot of midges around, and the characteristic areas, this is a, it's actually a picture of a cat that lives in Australia, where the disease was first, characterised.

But what you do see is very urtic lesions, usually around the, the nose. It's the less head, areas of the skin, so on the penny, and sometimes you can actually see them in between the digits as well. .

Management wise, obviously if you can keep your cat in at the times when the insects are feeding, that's ideal. But it's usually a case of using repellents. There's not great repellents for cats.

You can use fipronil, use a fipronil spray, and you can apply that fairly frequently. Daily or every other day, and usually you need prednisolone to downgrade the inflammatory reaction and control the pruritus. Now, you usually are familiar with herpes virus as an ocular sign or a respiratory tract infections, but we do occasionally see a herpes virus, causing cutaneous signs.

It's uncommon to rare, but usually you might have a history of having had an upper respiratory tract infection. And characteristic you'll see erythema, the swelling vesicles, you don't maybe see those clinically, those initial signs that you might see, but you see erosions and crusting over the muscle face and it can be quite very uncomfortable for the cat. Here's another cat.

I think the important thing to see in this case is that you tend to get the herpes virus tracking down the lamal secretions, so you will see it sort of dribbling down from the eye down to the nose. Here's a really severely affect cat, unfortunately, this cat was treated with corticosteroids, which promoted the viral infection, . The diagnosis of this, obviously the history is important, but biopsy, you can see an osinophilic epidermatitis, and the practise pathologists will be looking for basophilic intranuclear inclusions in the carratinocytes and supercytes.

The important thing here is that this can actually be mistaken for any sinophilic granuloma reaction. And obviously, if it's misread as part of the osinophilic granuloma complex, treatment with steroids may be introduced and that would actually make the herpes virus infection worse, . To further characterise it, you, you could do immunohistochemistry that's felt to be the most sensitive way, for looking for the herpes virus in affected tissue.

The problem with PCR is it's a fairly ubiquitous virus and once the cat's been infected, then it will carry the virus and false positives are quite common. I'm not going to go into herpes as far as treatments, in great detail, the normal things which to reduce stress, supportive care, antibacterial cover if necessary, and I've taken this table from one of my co-lectures in the BSAA postgraduate course, David Gould, and these are the antiviral drugs that he would recommend for treating herpes virus infections. Another viral infection in occasionally seeing cats, of the Kalichi virus again quite common, and it can cause a number of different syndromes.

In this particular context, we're looking at the case of the kittens where it causes oral and cutaneous ulceration and mouth and paw disease. Sorry, I went backwards there. So here's the young kittens with some ulceration of the nasal plane and you see it's a fairly characteristic pattern in these kittens.

So they can be febrile and anorexic. It tends to be a self-limiting disease and supportive care again is important. But the problem with diagnosis is really it can be isolated from most cats with chronic disease, and associated with the lymphocytic plasma cystic stomatitis as well.

Right, so we're staying with Viral infections and I wanted to look at papilloma viruses in the context of the skin. And this disease you see sporadically, and this is a squamous cell carcinoma in situ, which is often called Bowen's disease, and it's not, it's a pre-cancerous lesion, and you won't always see it on the nose. It can affect head skin as well, and they tend to have multifocal areas of this erosions and crusting occurring.

Now, the fiscal bonoids in situ carcinoma is, as I said, consollitary or multiple very pigmented packs, and nearly 50% of these bisc lesions have been shown to be positive for papillomavirus on immunohistochemistry. And a percentage of them will actually progress to become squamous cell carcinomas. And as a side note, they can be associated also with Demodex catti.

And that's just because of the local immunosuppression associated with these carcinomas. Treatment wise, so the viral papillomas, and viral papillomas by themselves can actually cause plaques, just isolated plaques in cats, but for surges lesions such as this, you're not going to do surgical treatment, but they can respond to a product called topical eiquimod, which is an antiviral which is used for herpes virus infections in women. And you get these little packets and you can see the before and after here, where the miwa has been applied to the bis lesion, and you've got to resolution.

My experience with these is they will often occur as multiple lesions, and it would appear that as, as fast as you treat the lesions with incrimod, the cat will develop other lesions elsewhere, and that's probably because of the viral papilloma papillomavirus, . Involved in the generation of these lesions themselves. But let's have a look at the relationship between, this is feline viral papillomass, and the in situs carcinoma and squamous cell carcinoma itself.

So you can have the viral papillomas, which are viral papillomas are part of the normal flora and cat skin, and they can cause nothing or they can cause viral plaques. They can cause these, in situ carcinoma lesions in about 17% of cases. And then some of these will go on to develop into squamous cell carcinomas.

But this this is to be differentiated from those squamous cell carcinomas, which will actually develop on lightly pigmented skin. And the much the percentage of those, sorry, the percentage of those developing on lightly pigmented skin into squamous cell carcinomas of the actinic or solar damage, much less 30% of those will have viral papillomas, whereas those who are on UV protected skin, the squamous cell carcinomas will actually have 75% associated with the papillomavirus as well. So that's just some recent research that's been done into that, but it's quite interesting.

Yeah. So finally, we're going to look at some depigmenting conditions. And first of all, this is a condition that we see sporadically, sometimes called snow nose, and to be honest, we don't really know what this is.

I was recently speaking in Scandinavia where they do see this, quite commonly in dogs, and none of the dermatologists then really knew the aetiology of this either. And these are, . Dogs that depigment their nose during the winter time and then they re-pigment again in the spring and summer.

But notice when we're looking at this nose that the architecture of the nasal plan is completely retained, so it's just the pigmentation. We get more concerned when you've actually got loss of that architecture in the nose, because to me that means there's inflammation or, or more concerningly, infiltration into the epidermis. So here is Alfie.

He's a case I saw recently, and his complaint that was, he's a young Labrador, about 2 years old, and the owners had noticed that he was losing the, he used to have a black nose and he's been losing the pigment around his nose and you can see some macular depigmentation occurring here. These were the biopsy sites, the referring vet had, done some biopsies of these, which had occasion to review as well. Now these owners were really, I was really impressed with these owners because the other thing they noticed was that, sorry.

Sorry, my screen keeps ticking. That Alfie's eyelashes are depigmented as well. Can you see that?

He's just gone, he's gone from having black eyelashes to white eyelashes. So this is a condition called vitiligo, and it's quite common in people. You see people where they've just had patches of white hair, white skin.

It's a progressive condition. It's often symmetrical, and there are a number of theories as to why this develops, but . The bottom line is that the pigment cells and the melanocytes are destroyed, and they won't repigment.

And this will be a permanent depigmentation for alphae. But it's not associated with any other systemic conditions, so it's a benign condition, and it's really more cosmetic than anything else. Contrast that, however, with this condition, which is the UVo dermatological syndrome, which we see more commonly in Akitas.

And this is also an immune-mediated attack on the melanocytes, but it will attack the melanocytes in the skin and also melanocytes which are sited in the uvea. In the eye, and that is the most serious part of the condition because if you've got damage to pigment in the ua, it causes the uveitis and these dyes, dogs can acutely lose their sight. So you got some deep pigmentation around the nose here.

. And and people it's called the fight rather sorry, VKH because in people it actually attacks and land sites and meninges as well, but in dogs it appears that We don't have a lot of melanocytes and meninges, so that's not usually generally a component of the disease. So diagnosis would be for your, combined ocular and cutaneous signs, depigmentation. And anti biopsy can demonstrate an inter face dermatitis as well with the loss of melanocytes.

These cases generally go to, in my experience, go to the ophthalmologist first, because it's much more, important, obviously the, the ocular signs are more acute and require immediate attention. And they really do need acute attention with treatment with prednisolone and other anti-inflammatory agents. And this is a, a picture from David Gould again, where the dog had eitis and secondary, retinal detachment is associated with the inflammation, so it can be a very serious disease.

And this is a case that Peter gave me, . Which, where the dog had actually lost its sight, so it had bilateral nucleations and it's still got severe ulcerative disease around the nose and it can affect the other nucleus cutaneous junctions as well. So This is a disease we see typically in older dogs, and it's again it's depigmentation, and this is a very rare form of lymphoma, where the lymphoma cells infiltrate the epidermis, and as a result of that, they tend to displace any of the normal cells in the epidermis, so the pigmented cells tend to be displaced from the basal layer.

And you'll get depigmentation occurring. And depigmentation around the mucous membranes in the nasal planar is often one of the earliest signs we see in epitheliotrophic lymphoma. So here's a westie.

I think the important thing to look at here in both these cases, you know what I was saying about the architecture of the nose, because you've got infiltration with lymphocytes, you've completely lost the cobbles stone architecture of the nasop planum. And he's a very, very subtle one, where you've got just got some early de pigmentation, but see again, we've lost the cobblestone appearance of the nose here. Now, sometimes we see these dogs just in the very early stages like this.

As they progress, they can get depigmentation around the lips, the the rest of the nose. And then it can cause some generalised erythederma, so they can get quite red skin and exfoliated scales, and these scales tend to be fairly large. Pruritus can be quite marked in these cases, which is associated with the lymphoma itself.

And at the terminal stage of the diseases they can it can cause ulceration and nodules forming. And this would be the diagnosis would be biopsy and you can see infiltration here of the epidermis with the lymphoma cells and it tends to occur in the Follicular epithelium as well, so you get a very busy looking epithelium, because of the, but when you look closely, these aren't normal epithelial cells. They're actually lymphoma cells which have infiltrated the skin.

There's a close up of that, you can see the, the busyness here, and these are lymphoma cells in the epithelium. Management, well, unfortunately, it's palliative, and, the, by the time these are diagnosed, I would say the prognosis is usually months . Some some cases I've had of maybe survived 12 to 18 months after diagnosis, but we do tend to see them at the fairly late stage because the early signs are fairly Subtle, but the best, treatment is a combination of prednisolone and CCNU Lomustine, which is a chemotherapeutic agent which is given every 3 weeks.

You do require to monitor blood work, when you're administering Lomustine, it can cause suppression of bone marrow and it can cause liver damage as well. And apart from that, topical moisturising and anti-scaling agents to palliate the scaling erythederma is quite important as well. So finally, I think I've got a couple of minutes left, a couple of examples of nodular disease affecting the nose.

Histocytosis is an uncommon disease and it ranges from a reactive to a systemic form, but when in characteristically, it can occur, you get nodules forming. Anywhere on the body, but it does often affect the nasop planum and a mucous membranes you can see here in this Bernice's mountain dog. That's another example of, cutaneous histocytosis.

And And finally, feline sarcoid, and now this is an interesting disease because it's very similar. I mean, almost identical histologically to the equine sarcoid, and it does affect young cats, they usually outside cats in rural areas, and it is caused by a bovine papillomavirus. But it's not the same as the bovine papillomavirus, which causes the sarcoids in the horse, it's a different one.

But as you can see, it's not a very good picture, but if you can actually see they tend to develop these focal nodules around the nasop planum and you can get them elsewhere along the face, . Philtre area sometimes around the lips. They don't metastasize, but they can re recur, so a wide excision would be required and the diagnosis would be by histology.

So that wraps up a run through a nasal diseases, and I would be happy to take any questions. Thank you, Hilary, just to see if anybody has any thoughts or questions. So we've got Sus asked a question, Hillary, she said, have you encountered very dry fissured nose with similar lesions in the paw pads, dry mouth, needed spoon feeding with wet food, and this was a cocker, dry eyes treated with specific therapy, not artificial tears, and probably related and very erratic, .

DM diabetes mellitus, I presume, on set when 12 years of age, survived 18 months, still enjoying life, although previous obsession with food was limited, wondering whether this, there was a link to SLE in the owner which erupted over the following 12 months. So it sounds like, did the, the owner got SLE . Over the following 12 months, so the owner had got it first or after the dog.

I yeah, I, yeah, I don't think there's a link, but if this dog from the clinical description and the fact that it had diabetes, I wonder whether it actually had liver disease as well. So, what we call the hepatic cutaneous syndrome, yeah. Often see that on the pads as well, don't you?

Yeah, yeah, you do. I mean, I didn't mention that here. I mean, it's more like the more common presentation is affecting the pads, which probably Peter talked about in one of his lectures.

So I don't know if that's helpful if you did any any haematology and biochemistry. Any other questions for anybody? Do you, Hilary, do you, do you think that epitheliotropic lymphoma could be a continuum disease?

The reason I asked that was because I've, you know, it's a, I've always found it a very interesting condition. And my own dog, had lip fold pioderma, which I, . Excised, and just because I thought, well, it's, I'm a good dermatologist, you know, I shouldn't throw tissue away.

I sent it off to Trevor Whitbread, who diagnosed it as epitheliotropic lymphoma. Obviously I was a bit devastated about this because on the whole, as you say, they don't last very long. We put the dog on steroids, 5 or 6 years later it died of an unrelated cause.

You know, there's that sort of continuum, when, when does the disease turn from being inflammatory to neoplastic, isn't it? Do you think there are some of those that are so mild, maybe that they never get diagnosed and, and we as dermatologists see the really difficult, nasty cases. I think we see them when they're quite advanced, and I've certainly had cases where we biopsied them and we've sat on the fence and said, well, this could be an early epithelial traffic lymphoma or it could be some inflammatory disease.

We've actually rebiopsied some of these dogs 2 or 3 times. And some of them have not actually developed the disease and then some of them have. But I think, you know, without any specific, I mean, and some of those actually we, we've run markers on as well, you know, looking for the CD3 CD8 .

But it's incredibly difficult to call in the early stages of the disease. So I think, I wonder with your case whether it was one of those that maybe it was an inflammatory disease that looked like an exulator. Not, not saying, I mean, Trevor Whitbread's a very respected, the matter of his pathologist, but I mean, I think it's, it is in the early stages incredibly difficult to diagnose.

I think I resent. Did I resend through, I can't remember, it's quite a long time ago now, but it, I know the histopathologists have this difficulty of reactive versus neoplastic in a, in a number of conditions. So it's it's a challenge.

I also learned fairly early on that I, I thought at the beginning of my career that pathologists were gods and never got anything wrong, and then clinical and, you know, histopathologists, and then I realised some of their diagnoses weren't right. They make the same sort of mistakes or, or, or they make mistakes like we do, don't they? Well, they do.

I mean, yeah, we're, we're all fallible, and I think the important thing to do is it's just part of the jigsaw puzzle. And the great thing about dermatologists is I get to see my the case and I actually get to review my own histopathology and there's, there's no. Actual replacement for actually putting that histopathology along with the clinical case that you've seen.

And that's certainly part of the training that we do is to actually look at both aspects of it. But even then, we may, you know, we're fallible and sometimes I, I still, after 30 years see diseases that I just can't but name. So I don't really know what's going on there, but I, I love this .

This new, well, it's probably not a new disease, but it's certainly one that I had missed out on the. Zero Mayteria, is that something you see. Yeah, how many of those would you see in a very sporadically, but I think since, yeah, since it's been described, we've noticed it.

I mean, it's, I think it's something to look out for. There's probably more of them out there. If you look at those dogs with KCS, they're not, we're not talking about every second spaniel, you know, but some of them will have dry noses and just look at carefully.

I, if you don't think about it, you never diagnose it, do you? Yeah, absolutely, yeah. Great.

Well, I don't think there've been any more questions. I've really enjoyed that. It's always good if you learn something new, which I did, so that's always a good sign, but obviously also some fabulous photographs, really enjoyed, looking at those and also just getting your insights in, into some of these challenging, but nevertheless very interesting conditions.

So Hillary, thanks so much for that. Obviously, the recording should be up in the next 24, 48 hours. I'm sure many of you will want to go back and and look at those when you've got, dogs with troublesome noses coming into the practise.

So Hillary, thanks once again and goodnight to everyone, and we'll see you on, the next webinar which is in about a month's time, so looking forward to that. Bye bye. OK, thank you.

Thanks, Hillary, bye bye.