Good evening everybody and welcome to this first in the series of the dermatology series. For those of you that are new, and you don't know how this works, if you have any questions, please feel free to just, click on the little Q&A box, type them in there and we'll hold those over to the end and our presenter Peter Forsyth has very kindly agreed to, to answer any questions that come through. So Peter Forsythe graduated from the Royal Vic School of Veterinary Studies in Edinburgh in Scotland in 1983 and he worked in mixed general practise for 14 years.
He gained the Royal College of Veterinary Surgeons certificate in Small Animal dermatology in 1992. He left general practise in 1998 and following a two-year residency, he gained his RCVS diploma in veterinary dermatology in 2001. He founded and is currently a partner in dermatology referral services with the centres in Glasgow and Aberdeen.
He's also an RCVS recognised specialist in veterinary dermatology and holds honorary lectureships in dermatology at both the RDSVS and the University of Glasgow Veterinary School. He has a particular interest in otitis and bacterial skin disease. Peter, welcome to the webinar tonight and sorry about all the confusion, but it's over to you for poto dermatitis.
OK, thank you, Bruce. First of all, thank you to everyone for joining us, this evening. It's a, a lovely sunny evening here in Ayrshire.
So potodermatitis literally means inflammation affecting the pores. And it's an extremely common presentation. It's, something that in dermatology referral practise we probably see, every day, and often.
Often several times a day. And, it's typically, owners will report the dog to be pruritic, so licking or chewing the paws, or pain in the paws, particularly manifested by lameness. Often these dogs that will, don't like walking on rough ground, they'll seek softer.
Roots to follow on grass to avoid, hard surfaces, . And proto dermatitis, you know, the pores are complex structures. So you have, the, the head skin, you have the heavily keratinized, skin of the foot pads with, without hair follicles, and of course, the, the nail structures, and disease can affect any of those areas.
And, tonight, really, we're mainly focusing on disease that can affect foot pads and, the head skin rather than, those diseases affecting the nails. And, and the disease can be confined to the pores. It can be part of a generalised, systemic skin disease.
It can be part of a, a, a generalised skin disease. And, and it's often, and there's no doubt proto dermatitis is a complex condition, and often multifactorial, and it's good to have a kind of framework within which to operate. So, we're able to kind of categorise the different things that can be going on and, and more of that later on.
One of the problems with proto dermatitis is especially diseases that are affecting head skin, is that they often look very similar. And I think if you looked at those 4 photographs, You'd be hard pushed to make a spot diagnosis, on any of them. In fact, they could all have the same disease, or in fact, they all have different diseases.
So the one on the top left is a dog with malacasia infection. The one on the top right is a bull terrier with a demidiosis. This one on the bottom left is a, a dermatophyte infection.
And the other one is atopic dermatitis, and they've all got hair loss, and they have hair loss for different reasons, either trauma, self-trauma or due to a follicular, inflammation. So the aims of this lecture tonight, really we're gonna spend a bit of time looking at the aetiology of proto dermatitis and. The different causes and factors that are involved, and this is where the similarity comes to otitis, because we talk about primary and secondary causes of inflammation, in otitis externa, and we're gonna do the same.
We're gonna apply the same principles to proto dermatitis and the various predisposing and perpetuating factors. And then a bit about the approach to a proto dermatitis case. And then I really kind of, I'm it's beyond the scope of this lecture to talk about treatment, all these different diseases that can affect the pores.
But I really want to focus a bit on, the management of what I would call chronic inflammatory proto dermatitis, and we'll do that by, means of a case presentation at the end. So Yes, the causes of proto dermatitis. So this is, as I say, this could be, you could substitute otitis for protodermatitis here.
And we talk about. Predisposing factors, predisposing factors are. Aspects Of either the dog or the dog's environment that will predispose towards the dog developing.
Inflammation on the pores, but they don't directly cause inflammation themselves. We also talk about primary and secondary causes of inflammation, and these are the things that, In their own right, can produce inflammation. So the primary causes of inflammation may be many and varied, .
And they may produce signs that are so subtle that they go unrecognised. To start with, or they may produce quite significant clinical signs, that, result in the dog being presented for the primary cause. But in the cases where the signs are very subtle and go unrecognised, it's only when the dog starts to develop a secondary cause of inflammation, and these are really mainly infections that the dog will be presented with proto dermatitis.
And then both primary and secondary causes of inflammation can eventually lead to chronic changes affecting the pores that mean that disease is difficult to resolve. It it's, it persists. And, and.
Results in these perpetuating factors that also in themselves result in further proto dermatitis, and we'll look at what all these, causes and factors are over the next few minutes. So first of all, I just want to look briefly at predisposing factors. So there are a number, there are a number of these, and this list is not exhaustive, but.
Dogs that live in a dirty environment, an unhygienic, wet, or, you know, a dirty kennel environment, for example, which will result in maceration of the skin on the pores and predisposed to secondary infection. Lack of grooming dogs that develop. Hard masses of mud and and and matted hair in the spaces, the clefts deep between the footpads.
Will certainly irritate and inflame the skin and probably cause some erosion of the skin surface and predispose to to infection. And then there are patient factors. So dogs that are overweight, bearing more weight on their paws, will predispose to .
Pedal problems, confirmation of the paws can be an issue, and this is a thing that we see quite commonly, this photograph on the right. I hope you can see my pointer, OK, but you see these, this dog doesn't yet have a problem with his paws. The paws are not inflamed, but they have this horseshoe-like configuration of the two central digital pads, and you have this area here, which is really headed skin.
This is coming in contact with the ground, and that can cause, eventually cause problems. And then, musculoskeletal disorders, so resulting in abnormal gait, we'll look at an example of that in a second. And can, you know, underlying immunosuppressive diseases, whilst in themselves, such as, for example, an endocrinopathy, hyper hyperthyroidism.
. So, can they, while the, while the, underlying disease doesn't directly cause inflammation of the feet, it can predispose to infection. So here's a dog, an example of a dog with very, poor gait.
There's a kind of valgus deformity here. And this results in the dog bearing weight on the inside aspects of the foot pad. They're not bearing weight evenly on the foot pads, and the footpaths are not wearing in an even, manner.
And, The the thing here is that the dog is starting to bear weight on the head skin at the edges of the foot pads, and head skin is not designed for weight bearing. So so much for the predisposing factors. I want to go on now and look at the causes of inflammation, the primary and secondary causes of inflammation.
Just a reminder, the primary causes are those diseases that result in inflammation in their own right. The infections, the secondary causes. As the name says, secondary, there has to be some underlying primary disease process before an infection, sets up.
So here's a bit of a long list of primary causes of inflammation in the pores, and I'm going to highlight and just pick out two or three of these and look at these in more detail. But we can divide them into infectious causes of fungal infections, parasitic diseases, dematocosis is a very important one, but things like hookworm or leishmaniasis, viral infections, or papillomavirus can affect the foot pads, . Bacterial infections.
I'm really here thinking about atypical infections, so that might be a, a cat, for example, that's been bitten by a rodent and has a a a a a . A, a TB lesion on the pore, for example, or a mycobacterial infection on the poor, I mean. Immune mediated diseases, allergic diseases, ectopic dermatitis, very important cause of, proto dermatitis, primary cause of, of inflammation, autoimmune diseases, hepatocutaneous syndrome, we'll look at in a second.
And then there's a host of other things, nutritional factors, creatinization defects, environmental effects, burns, frostbite, contact reactions, foreign bodies, and so on. So we're not going to look at all these, but I'm gonna pick out two or three really important ones. And probably the, the, one of the two most common primary causes of inflammation in the pores is, atopic dermatitis.
And they, the, the, usually the distribution of, of these dogs initially usually present with nonlesional pruritus, and the classic distribution is, It's periocular, the muzzle, the axilla, the sort of ventral areas, perineal and pores. But there are some dogs that just present with pedal pruritus, and, and this dog here on the right is manifested by Mark's saliva staining on the paws. There may be secondary lesions that develop, mainly associated with self trauma and and secondary infection.
So here are some typical photographs of proto dermatitis associated with atopic dermatitis and this erythema between the foot pants is a very common sign. This could also be associated with a yeast infection or a bacterial infection. Inflammation, over the dorsal interdigital web.
More severe inflammation of the planter aspects of the pauses between the pads, it's important to Separate the pants and examine the skin in between the foot pads. You've seen this photograph already, but this is self-trauma due to atopic dermatitis with a very well demarcated margin to the, to the alopecia, and, you know, you could look at that, it could easily be a dog with dermatocosis. More severe inflammation, and this dog on the right has, is starting now to develop quite probably what is a severe bacterial or yeast infection in between the pads.
I'm not going to say any more about atopic dermatitis, but it's just, I want to highlight its importance in protodermatitis, and it is probably the most common primary cause of inflammation. And as I said earlier on, that sometimes the signs associated with the atopic disease may be very mild, and it may only be that when the dog develops a secondary infection. That the dog is presented, but it's always important to look for that primary underlying cause.
Portodermaticosis is the other common primary cause of poo dermatitis. It's only going to affect head skin. The, the mites live in hair follicles so the foot pads will not be affected.
And, It is . It may be confined to the, the pause or, or it may be part of a much more generalised presentation. We do define podo demadiosis as a form of generalised demodex infection, and it may be a juvenile onset or adult onset, and typically these dogs are either pruritic or painful, the pores are very often severely inflamed.
And one marker for that is, is, regional lymphadenopathy. So if you palpate those popliteal or pre-scapular lymph nodes and, and they're enlarged, it always it should raise your index of suspicion for, for dematicosis. And it has a very varied presentation as well, you know, from relatively just fairly subtle erythema and a bit of hypertrichosis on the pores to more extensive alopecia, to really quite dramatic alopecia and that characteristic kind of slatey coloured pigmentation that you see with quite marked scaling.
And here's really severe, pooematicosis and these pores are very painful to touch. Dog's probably going to be lame, biting, chewing the paws. And this one here, a bull terrier.
This dog's starting to get some quite severe secondary changes in the pads with a lot of weight bearing on head, skin. So there's the pads here and here and down here, and all this is excess tissue, that's, that the dog is bearing weight on, not designed for weight bearing that skin, and, and that's causing further problems. And here's a dog with, obvious generalised demidiosis.
Autoimmune and immune, other immune mediated diseases, . Can affect the pores and typically result in crusting or scaling, or erosions or ulcers of the foot pads very often, and they can affect other areas of the pores as well, but typically you'll see foot pad involvement with, with many of these. Pentheuss foliaceous is probably the best example, and one of the most common.
They're not common diseases, but that one of the more common autoimmune diseases that we see. And, and this dog on the left has, it's a crusting skin disease, a sterile, pustuar, and crusting, skin disease, and you can see the crust that's accumulating on the head skin here. And here's a dog with, footpad erosions and footpad, some hyperkeratosis, and, and some scaling here.
And, you know, with the foot pad involvement like that, then, you know, you may well be dealing with, with an autoimmune disease. There are other diseases that can affect the pads in that way, and we'll look at one of them in a second. But autoimmune disease such as pemphigus is high in a list of differentials for that.
Here's a couple more on the bottom right, here's a dog that was diagnosed with cutaneous lupus, which more commonly affects the face, and, or the, the nasop planum, or the pinny, but can also affect the foot pads and this, this was an erosion of one of the foot pads. And this dog had quite subtle lesions. This is a post-viral erythema multiforme, quite subtle, Mildly crusting, erosive lesions adjacent to the footpads, and this dog also had lesions on the buckle mucosa.
Vasculitis is another disease where you can get, you potentially get full thickness ulceration of the foot pads, and disease may just be confined to the foot pads. And indeed, in pemphigus foliacious, occasionally some dogs just present with footpad lesions or in most circumstances, it's a generalised, a more generalised disease. And the diagnosis of these cases is nearly always going to be on a combination of clinical signs, cytology, especially in the case of Penhagus and histopathology.
Just a word on Biopsying foot pads, . It, it's quite challenging often to get diagnostic samples, and you really need to watch, especially for a disease like pemphigus, which is a A, a pustuar or blistering, you'll, you'll see separation of the epidermis. And you need to try and get the margin of the separation, the, the junction between the normal and the, and the skin and the, where the pustule's forming, and get it at the right time because once it reaches this stage where you've got an erosion, biopsying the erosion is not gonna help with the, with the diagnosis with the diagnosis, I'm afraid.
Loop on a dystrophy, I'm not gonna say a lot about nal disease, but this is one of the more common other immune mediated diseases that affects the pores, and I couldn't do this actually without including at least one slide on, on this condition. This is a presumed immune mediated disease which results in progressive nail loss, and, and classically you get this lysis of the nail, the base of the nail, and this gradual loosening and separation, and then complete loss of, of the nail. And, that process progresses over a period of time, so initially the dog will present with one nail and typically, the assumption is that it's a, a traumatic nail loss, but then over time more and more nails are lost, and then the penny drops that we're dealing with something else.
And here's a slightly more progressed situation, and, the treatment for this disease, this is all I'm going to say about lopoidontic dystrophy, but removing loose and broken nails, which is, you do it by just gently pulling the nail off or loosening it and removing the nail and leaving the underlying quorum. Cytology and treatment of infection, nail care, and then in fact the nails will regrow, but they grow in a dystrophic manner, hence the name, and they are anti-inflammatory and immunosuppressive therapy. Can be helpful in, in encouraging healthier nail growth.
Another disease that, another disease that can affect the foot pads, and again, it's usually part of a much more generalised condition, is necrolytic migratory erythema or some of you may know it's hepatic cutaneous syndrome or metabolic epidermal necrosis, are all synonyms for this disease, which is a condition associated with, usually chronic liver disease or a glucagonoma. And these dogs are often overtly diabetic. It tends to affect older dogs, and the skin lesions are a marker for the internal disease and this is a, a liver from an affected dog, and here's the scrotum from that dog, which was severely inflamed and eroded.
And, and here are foot pads, the paws of dogs are two cases of hepatogenia syndrome, and you can see the severe erosion and fissuring of the foot pads, and the same with this one here exposing really sensitive underlying tissue. And these. Footpad involvement is often the reason that these dogs are euthanased because it gets to the point where they, they find it difficult to, to walk.
And this is a disease, you know, you could look at this, this could easily be an autoimmune disease like Penhagus, for example, easy to confuse the two. But with this disease, you're looking for systemic signs. Weight loss, anorexia, signs of diabetes mellitus, and, further investigation in, in terms of blood work and liver ultrasound is certainly indicated in any case presenting those signs.
Footpad hyperkeratosis is a thing that is another primary cause of, pedal disease, and there are congenital footpad, hyperkeratosis. This is where the foot, the, the keratin footpad becomes really thickened and fissured, and the fissures can penetrate through to the under, through the epidermis and result in, in pain, and, and lameness. And there's a couple of breeds, or at least 2 breeds where congenital footpad hyperkeratosis is, is recorded, the Dog de Bordeaux, this is the, the footpads of one of the doctor to Bordeaux.
The Irish terrier is another one. And there's a, a condition in the Labraator or retriever, which is not that uncommon at all, which is congenital nasal parakeratosis. Where you get this hyperkeratosis of the kind of dorsal aspect of the nasal planum, sometimes those dogs will also present with footpad lesions and sometimes lesions on the pinny as well.
This is a papillomavirus infection that we saw in a Labrador retriever quite recently, and this, this digit had to be amputated and, and this lesion was also removed and and . The dog made a good recovery, but, so papillomavirus is the thing to watch out for, and corns in, in greyhounds are another rare cause of footpad hyperkeratosis. This is the corn that's actually been removed, sort of shelled it out, .
All possible primary causes of inflammation, and occasionally we'll see dogs with really quite marked, severe footpad hyperkeratosis, where we cannot find an underlying cause, and there, it's often an older dog, and the, the, the suggestion is that perhaps this is some kind of, senile change. And all you can do with these, these dogs is really, and indeed with the congenital cases, is just to trim the excess soften the, the excess keratin and trim it away, to maintain some sort of more normal footpad, shape. OK, so that's a very quick look at some of the primary causes of inflammation.
I want to move on now and look at the secondary causes, so these, These are basically infections, and there are two main infections that we see, malacasia dermatitis, that is a very common problem, and staphylococcal infections. So malacasia infections, very common cause of pedal pruritus and should be top of the list of differentials or are at the top of your list of differentials for any dog that's presenting with, with pedal pruritus. And usually, it's secondary to an underlying disease, typically, canine ectopic dermatitis, although there do seem to be certain breeds that Like cocker spaniels and, and basset hounds, that seem to be predisposed to develop malacasia infections without an obvious underlying cause.
And typically these dogs present with pruritus and erythema and, and sometimes a hyperpigmentation of the . The, the skin between the foot pads and between the digits. Often you get this greasy exudation and sometimes you get a brown discoloration or brown banding around the nails.
We'll have a look at some of these. So on the top left, this is a Labrador with malaysia dermatitis, and this is a classic kind of, this kind of erythema and this slightly shiny, greasy appearance of very typical of malacisia dermatitis. Here's a golden retriever with more severe inflammation.
This dog had, I mean, all, both these dogs had underlying atopic disease. More, again, more severe inflammation again on a Westie's paws, quite marked erythema, and more of a brown discoloration here, brown sort of greasy appearance, on the paws. This is a boxer.
And this is this brown banding that I was talking about, this brown discoloration of proximal nails. This isn't always caused by malacasia infections, but it, it, it's a marker for it, for sure. And when you treat the yeast infection, you can see the normal nail colour growing out.
So the other, the other type of infection which you commonly see are, is bacterial, proto dermatitis. And, again, very frequent problem, secondary to an underlying disease process. And it has many differing presentations, and it's easy to get caught out by bacterial skin infections and, and, and, not be aware that they can be involved, because it doesn't, they don't typically present in the way that.
Pioderma represents and the rest of the skin. So you tend not to get pustules and papules and pustules and colorettes and erosions. Often you get much less, the signs are less specific.
And the signs depend on the depth of the infection. So it could, if it's a very, if it's a surface infection, it might be just erythematous and scaly. if it's a very deep infection or a deep pyoderma, then this is when you start to see draining tracts and, and much more severe swelling.
And mostly, as with yoderma in other areas, it's mainly caused by staphylococcal infection, but there are other bacteria that can be involved. So here's what we call, you know, you could call these more surface or superficial type infections, where you've just got some erythema. Bit of brown discoloration of the hair.
I mean, I think you'd agree that this could easily be a yeast infection, and similarly with this one here, and it's only when you do the cytology that you identify, that it's bacterial. Deep pyoderma is a really, is, is a common problem with proto dermatitis, and it can occur. Secondary to demidiosis, and it can occur secondary to underlying atopic disease, and it can be the end result of some of these perpetuating fractures was where you, where we end up with weight bearing on head, skin.
And typically there's quite marked swelling. Often these dogs are painful, and lame rather than overtly pruritic. And this is where we see draining tracks, particularly on the footpad margins, or these interdigital lesions.
These things that we talk, we talk about interdigital cysts, these are not really cysts. They are granulomatous, or lesions, abs and or abscessations, with a draining tract. And if you see a draining tract on the dorsal aspect of the pore between the between the digits, you need to turn the pore over and have a look at the underside, to see where the problem is originating from.
So these are all examples of deep yedema. They all look very different, but you've got these, the swelling and, alopecia and erythema encrusting here and similar lesion here with a, a draining tract. This is, This is going to become an interdigital cyst, but it's a large or, or it's an intergenital draining tract, but the kind of thing that we might call a cyst, .
At this stage it's a hemorrhagic buller and it's just about to rupture and it'll in a, in a, A few days' time it'll look like this, the swelling will go down and you'll just have a draining tract that's oozing a little bit of pus and this is what people call cysts, but . They're not cysts. They are inflammatory lesions.
On the plantar aspect, aspect of the poor here, you've got very severe swelling, and again, draining tracts, and some of these, if you give these, pressure, you can, they will rupture and you'll get a hemorrhagic pus, coming out of them. And here are some more subtle deep piodermal lesions, these little areas of erythema and swelling and exudation in between the, the pads and just adjacent to the footpads as well. You can see that, that this is a very typical area for them to form, not on the footpads themselves, but in the head skin adjacent to the pad.
And it's, it's important to recognise that this is a, a, a potentially a deep bacterial infection, because the treatment for this is probably going to require systemic antibiotics, whereas the treatment for the surface infections can be managed with topical therapy, mainly. So with chlorhexidine containing products, wipes, shampoos, mousses, sprays, and so on. Bacterial parachia is another form of bacterial infection where the all the nail folds are affected, and if you see this, you have to wonder whether this dog has some underlying immunosuppressive disease.
Could also have demiticosis. So those are the secondary causes of inflammation, and then I want to look now at the perpetuating factors, and these are often like in otitiss, these are often the reasons that that disease is persisting and it's difficult to, to, It's difficult to cure the condition. So what are perpetuating factors?
Well, these are changes that occur within the feet in response to long-standing inflammation, and that inflammation might be the result of a primary or secondary cause. And predisposing factors may also be involved. So if the dog has this congen this, these congenitally conjoined central digital pads, where there's weight bearing on head, skin, that predisposes, to, chronic inflammation.
And, and the perpetuating factors, as we said, they, they prevent resolution of the disease, even when you deal with the primary cause. So you might, you might identify that stock has atopic disease. You deal with atopic dermatitis, but the disease with the pores may well persist.
And the most common thing that we see is that. A combination of a primary inflammation maybe from A to B and, and the secondary infection results in some swelling of the foot of the tissues on the plantar aspect of the poor. And the.
The, the foot becomes, the poor becomes infected and there may be, as I say, some, some, confirmation issues as well. So the dog starts to bear weight on her skin. What we think happens is that this, the, the, the, the weight bearing results in, in-driven hair shafts that cause further damage to the skin, so they probably penetrate through the hair follicles, so you get.
Hair released into the dermis where it shouldn't be, and the body recognises that as a, as foreign tissue and mounts an inflammatory response against the buried hair. And on top of that, you see, you'll, there is secondary infection, so folliculitis and ronchiosis. And all of that results in further inflammation and further swelling, and eventually dogs can end up with this, we term it false pad situation where, you know, they're no longer bearing weight on the foot pads, they're bearing weight on this very swollen tissue between the pads.
And the inflammation that's deep within that tissue, . You know, you start to get, you'll start to get a buildup of pus, and that pus has to go somewhere. And where it goes is it tracks dorsally out between the interdigital webs, to form what we call cysts, but we've already discussed, they're not cysts, they're, they're granulometers, sort of abscessations.
So Here's the kind of thing we're talking about. So this dog has lesions between the digits, and if you, you know, this is ruptured at some stage and probably discharged a hemorrhagic pus, you can see there are some gait. Conformational, not gait, abnormalities, but conformational abnormalities.
This dog's toe is turned out to the side, and that may be the result of the, the, the changes, or it could be a predisposing factor. And if you turn the paw over and have a look underneath, this is typically what you see. So you see the foot pad down here and here and here and across here, but you've also got this massive swollen tissue here and here and a little bit in here.
And so the dog is actually bearing weight on this surface here, and this surface here and and this surface here, and this is creating inflammation which eventually abscess and tracks out. The dorsal aspect. And in some dogs The some dogs have very upright paws and very deep clefts between the paw pads, and when you open up into them, you see this very deep, cleft in here, where the skin is quite macerated and inflamed and prone to infection as well.
So that's another thing to look out for. And here's some other similar examples. This is a thing that condition that we see quite a lot.
So again you've got your foot pad up here and down here and down here and down here, and this dog is actually bearing weight on this tissue here. Similarly with a beagle. Beagles are a, a breed that are highly predisposed to developing these sort of foot pad chains for, changes.
This is a westie, and here's this sort of conjoined, tissue between the pads, in this example here. But, you know, the pads are here and here and here and here. And again, this dog is bearing weight on all this tissue.
A large breed, I think a mastiff with really severe changes. Look at this dog here, this looks the same, but it's just to kind of alert you to the fact that actually not all dogs with these sorts of changes, just, this is not always just a chronic inflammation, this dog has demidiosis. They'll never forget to look for these primary causes.
So, if we're investigating proto dermatitis, how do we go about that? Well, a methodical approach is needed, . History, .
Which is probably going to alert you to probable primary causes of inflammation, the, the pruritic dog situation. Full examination, examine the entire skin, and close examination of the pores, dorsal and plantar aspects. It's worth assessing gait and weight-bearing.
There may be some obvious abnormalities and, and draw up a differential diagnosis list. And, you know, typically on your differential diagnosis list, it's gonna be diseases like atopic dermatitis and, dermatocosis, and the basic sort of, tests to do. The, the first things to do first of all, rule out parasitic disease, in particular demidiosis, and, hair plaques can be very useful.
These are hair plaques here from this case, and you can see the demodex mites in here and also a demodex egg. Negative hair plaques don't rule out demidicosis, so you may need to sedate the dog and take skin scrapes or even samples for histopathology. Cytology, tape strip preparations to look for yeast and bacterial infections or impressions means from draining tracts, to look for, evidence of deep pyederma.
Culture and sensitivity testing. Histopathology may be useful, and we'll look at that in a second. Allergy workups may be required and investigation of possible underlying diseases such as endocrinopathies.
And cytology is the, is the . The number one test to look for yeast infections and you can use a tape strip preparation. You can, with the dogs with this brown staining, it can help to use, perhaps a plastic, cotton bud, or plastic applicator and just scrape some material out from the nail folds and smear that onto a slide and have a look at it.
And, and, and examine under the. All, all the Martian lands for, for, A maesthesia. So cytology, very important.
Don't have time to go into all the different aspects of cytology, but I wanted to highlight this situation. So with these dogs with deep pyederma, interdigital cysts in inverted commas, what you typically see on cytology is this pyogranulomatous inflammation, where you've got a combination of neutrophils, and macrophages. There's also an ASXinophyll in here, and there's some red blood cells here too.
And what you often don't find a bacteria. That doesn't mean they're not there. Bacteria are usually easy to find with the more surface or superficial infections, but trickier to find with deep infections.
And it, it, it is a problem, knowing when you see this sort of cytology, knowing whether you, whether you're dealing with infection or not, and culture as is indicated in these cases. So we would culture where you see deep pyederma, where you see unusual organisms and cytology such as rods. If there's been previous poor response to treatment, multiple previous treatments, or, or possible exposure to resistant infections.
And, and the question is, what do you culture when you've got a lesion like this? Well, you might be able to express some pus from a draining tract that may be fairly representative of what, of what's deep within the tissue. But typically, when we're working up these cases like this, we like to biopsy these, or we'll often biopsy them, and we'll send, using a biopsy punch, and we'll send half the tissue for culture and the other half for, histopathology.
So we're getting a culture from deep within this swollen tissue, and we know what's growing in there. So, I, I want to kind of finish off this lecture by just looking at a, at a typical case of chronic inflammatory proto dermatitis and how we approach this case and the different options for managing these difficult cases. So this is an eight year old male.
Neutered cocker spaniel actually, that we first saw in April 2016 and, and he presented with a very long history of, Quite severe proto dermatitis, into digital cysts. If you wanna call them also had a history of prurituss and, and otitis externa. And, he'd before he was referred to us, you know, because of his history of pruritus, quite rightly, the vet, the referring vet had done.
Some investigation into the causes of the pruritus, and he'd been on an elimination diet. And he'd had, prolonged course of antibiotics, and on several occasions actually, and bathing of the pores with a chlorhexidine, wash, all perfectly reasonable things to do. And, one of the things that had been noted was in areas where it'd been clipped for, for, Blood sampling, the hair had failed to regrow.
So this is how he looked when we saw him. And I think if you look on this top left photograph, this is the epitome of a tragic facial expression, and you can almost say the skin is quite mixedematous around the eyes. So hyperthyroidism was top of the list of Possible underlying diseases here.
And when you looked at the pores, you see how severely affected they were. So you got the foot pads are way down here, here and across here and this one here. And actually this massive tissue is causing the foot pads to be pushed outwards and forwards, so they're no longer bearing weight, and you can see the end result on the dorsal aspect of the pool where you've got draining tracks, severe swellings.
This dog was in a lot of discomfort and actively avoided walking on hard ground when whenever possible. So the differential diagnosis in this case, definitely a deep pyoderma. He could have had dematocosis for sure.
There may well have been a yeast infection involved in the deeper these deep clefts between the pads and, and the, and the digits. Certainly, there are, there's a lot to suggest that he that he, he has hyperthyroid. He could also be a topic.
And maybe he had as a predisposing factor a long time ago, and a lot of cocker spaniels do, perhaps he did have these, sort of horseshoe, confirmation of the central digital pads. So, the investigation, our initial approach, we took some hair plucks from the pores, we sedated him and did, did some skin scrapes, and we didn't find any evidence of demitocosis. We did cytology and found piogranulomatous inflammation from these draining tracts with a few cockey, and often you just find it, you may just find a few cockeye or none at all.
We did do some blood work on him and urine analysis, and there was no doubt the blood showed, the blood work showed he was profoundly hypothyroid. And We biopsied the poor, so I took samples, a biopsy, and he underwent a biopsy procedure using a biopsy punch, and we submitted the tissue for histopathology, which showed just chronic inflammatory changes and evidence of deep pyederma. And, we also submitted tissue for bacterial and fungal culture, and you can see on the right.
That this, that he had actually he did have a methicillin resistant coagulase negative staph and a staff sued intermediate. So our initial treatment was to kind of deal with the hyperthyroidism and also to treat potential infection, and we selected doxycycline as an antibiotic that was effective against both bacteria that were cultured. And, two months later, there was a marked improvement in his demeanour, you know, treating the hyperthyroid, he was a much brighter dog, but the interdigital swellings and draining tracks persisted.
He still had severe swelling on the pores, and still had these interdigital lesions. So the prolonged antibiotic treatment really hadn't made any difference, and that's not uncommon in these cases. You, you may well find initially you get a good response to appropriate systemic antibiotic treatment, but that after a while, the lesions recur, or you may find you see no response at all, and that's because.
It's not primarily an infection at this stage. There may be a sterile inflammatory process that's driving the the inflammation. So the options, having, once we're sure that we've got rid of the infections, our option, and the lesions have persisted.
What we've then got to focus on is dealing with the inflammation in the pores and trying to restore the the weight bearing to the foot pad surfaces to improve the dog's quality of life. So, The two options really at that stage would typically be glucocorticoids, prednisolone, or cyclosporin. And just to show you that, that, that that approach can work, on the right, you'll see photographs from, this is a Westie, that was sort of a few years ago now, and this dog presented with chronic poo dermatitis.
And we adopted exactly the same approach with this case as, as with the cocker spaniel I'm discussing. Eventually, we did treat this dog with cyclosporin, and this is how the pores looked a few months later. So, once you get rid of the infection.
These drugs can, in some circumstances, be quite effective at resolving this excess inflammatory tissue. The other option, potentially, is surgery. And, and, fusion protoplasty would, is where all the inflam inflammatory tissue is pretty drastic surgery, but all the inflammatory tissue, all the head skin, I'm sorry, between the, the toes and between the foot pads is removed, and everything suture together to form one large foot pad.
It's pretty drastic surgery with a prolonged and difficult recovery period. So anyway, with, with the cocker spaniel, he was started on methylprednisolone and actually. Quite typically with these situations that there was a really dramatic response.
So within a couple of weeks, the proto dermatitis was an awful lot better and the tracts had healed and the pedal pruritus had resolved. What we found after a few months was that he was reasonably well controlled, but any reduction in the, in the methylprednisolin dosage resulted in recurrence of, of the lesions, and we felt that the dosage was probably unsustainably high. So we had a further discussion of treatment options with the owner, and whether we would try him on cyclosporin.
And at this point, we started to use CO2 laser to remove, to, Excise this excess inflammatory tissue. And the owner was keen to try this. So this is how it looks.
So this is the dog's paw before surgery, and you can see the severe swelling in here. A foot pad right down here and over here and over here and over there. This is immediately postoperatively what we use, we use the laser just to remove all that tissue in there.
It's a bit like doing a fusion protoplasty, but without suturing anything. And this is the tissue that was removed. So that was immediately post-operative.
They require a lot of aftercare, but 4 weeks later, it's starting to heal nicely and you can see the foot pads are coming back into the correct position, probably partly due to contracture from scarring in here. And that's how it looked after 8 weeks and 16 weeks. And then after 11 months, that's how the poor looked.
Now, I'm not going to pretend this pore is completely normal, because actually he still does occasionally get some, there must be some residual inflammation, occasionally the odd cyst will come up here, which responds pretty well to a, a short course of glucocorticoid therapy. So far, this is one of the first cases we did, we operated on. So far we only did one pool, the other pour is still to be done.
But it is another option for managing these chronic inflammatory pro dermatitis cases. So I'm gonna wrap it up there, and I'm gonna say just in summary that that protodermatitis is a complex multifactorial condition. You know, there are these primary and secondary causes of inflammation, and it's important to try and identify.
What's going on and deal with each, problem, do you, identify and deal with the secondary causes of inflammation and may, you may, may be only after you've dealt with the secondary causes that the primary cause of inflammation starts to become apparent, and wherever possible, deal with these predisposing and perpetuating factors. And, we, you know, with these cases, a methodical workup is really required with a, with a more complex cases where you need a good history, careful examination, make sure and rule out dematocosis first and foremost, do your cytology, do the culture, histopathology, and any further investigations that's required. And in those dogs with chronic inflammatory disease, where you've dealt with the infection, you're sure they don't have demiticosis.
Then, it can be worth trying some immunomodulatory therapy or considering the option of surgery. OK, well, thank you for, for listening. I'm, I'm gonna hand back to Bruce now and I'm happy to take any questions if, if, if there are any.
Peter, thank you very much for that. That was an absolutely amazing overview of an incredibly complex, sort of syndrome because as you said a number of times, there's there's so many drill downs on each of these sections that it's not really possible to cover them all, but somehow you've managed to do that. So thank you so much for that.
It's a bit of a skim over them, but anyway. Just an interesting one. When you get these dogs in with these so-called interdigital cysts and and you've looked at them and you can't find, and of course at this time of the year, grass seeds are a nightmare because you see them and you don't always find the grass seed and if you're really lucky, it's almost like having a celebration in the practise when you find one.
But the the feeling recently seems to be, you know, moving away from antibiotics. So open them up, look for foreign bodies like grass seeds and if you don't find them repeatedly flush them out and then Just give them a chlorhexidine based rinse and with or without some non-steroidals. How do you go differentiating those from the more complex deeper piodermas?
Well, I, I don't have any pictures of grass seeds, cause, I, when I first graduated I work, I worked in Sussex, and we used to see a lot of dogs with grass seed, lesions on their, sometimes on their paws. Somehow in the west of Scotland, we must have different species of grass, or maybe it's so wet that the grass never seeds, because it's not a problem that we see very much. Now that may be a reflection of the fact that I work in referral practise now, rather than, primary care, but, the difference is that, you know, the, the, and I remember those grassy cases very well, but they're very acute cases.
So the dog probably doesn't have any previous history of, of, skin disease, or and no previous problems with the paws, and it just presents with this great big swelling between the digits. And if you were to turn the paw over and look at the underside, there would be no. Pathology there.
So the foot pads would be in the correct place. Weight bearing would be on the footpad surfaces, and you wouldn't have the swollen tissue between the pads. And, you know, clearly, if you, if it's an acute onset case, that case needs to come in and have that abscess opened or the, the, the, the lesion opened and flushed out and hopefully the grass seed retrieved and, you know, I'm not gonna, I mean, I, I think now the trend would definitely be not to treat those ones with antibiotics to get rid of the grass that probably sorts itself out.
The chronic deep pyedermas, you know, they, they, I have treated them actually, in fairness, we have tried treating some of them with topical antibiotics, but for, for these very deep lesions, you're probably gonna need prolonged systemic. Antibiotic treatment based on. Appropriate culture and sensitivity testing, and, and you know, you're talking about weeks, 6 or 8 weeks of treatment, to eliminate those very deep infections, and I, I don't think anyone would argue that there's still an indication for systemic antibiotic cases in those cases.
Mm. Yeah, fair enough. I think the key factor there is the differentiation between no lesions, ventrally, between the pads.
I think that's a key take-home message. Another quick question for you, how do you feel about, the spray on, corticosteroids like Cortivans? Yes, so Again, I mean, that's it's a good question.
I, you know, I, I apologise for not covering that in the lecture, but you just, that would be another lecture on the management of atopic dermatitis. But there are studies that show that, topical glucocorticoids in particular, hydrocortisone acephanate, which is in cordovans, can be effective for managing pedal pruritus. How do I feel about them?
. I don't think I have strong feelings either way, but they can be effective. And if you have an owner who's willing to use them and a dog who's happy to accept them, then and, and the, the pruritus is relatively localised, they just confined to the pose. Well worth a try.
And, but they won't, what I would say is they won't treat. The prurituss associated with a yeast infection or a bacterial infection. So you've got to manage the identify and manage those, those, those infections, but it's just purely atopic disease, yeah, definitely worth trying.
Owners tend not to like them, you know, some owners are fine with them, others are less enthusiastic. And I, I find the dogs are very non-enthusiastic about that, that sort of sound. I think that tends to freak them out, so you end up having to put it on cotton wool and dab it on, and I don't think that's quite as effective.
Perhaps not. Yeah. Well, Peter, that's it.
I, it's been an absolute whirlwind, but you've really covered it and you've given us a deep insight into these problems and that sort of thing and that was pretty amazing. So thank you for that and we'll have you back in a fortnight I believe for Oitis which I look forward to. Thanks very much.
And to all the people that have attended, thank you very much. Joanna is my controller in the background. Thanks for making things happen.
And we'll see you guys on the next one of the dermatology series. Thank you and good night. Thank you.