299. The many faces of pyoderma

Welcome to the Dermfet Podcast where PET skin is always in. I'm Dr. Ashik Buzwa, board certified veterinary dermatologist, skin nerd, and your go-to guide for everything itchy, smelly, and inflamed. I'm here to take the itch out of your day and make Derm more fun than frustrating. Grab your microscope and let's focus in. Welcome to another episode of the Dermfet Podcast. I wanted to go over some basic presentations of what pyadermic can look like. I've had some new grads, some people who've been out for a couple of years and just really starting to get more interested in dermatology. Ask me, you know, we talk about pyadermic being such a common thing that we see in dogs and cats, managing lots of skin disease, especially lots of allergies, what does a pyadermic look like because it's not always the same typical crusting that we think of. And my hope is to explain some different presentations of pyaderma, a couple differentials, and then if you check out the YouTube version or if you're watching the YouTube version now, actually showing you some clinical images of what a pyadermic can look like. And of course, I'm not even gonna worry about saying this over and over again because you guys know and love it, cytology, everything. Really, when it comes down to pyaderma, the best thing is to collect cytology and look for signs of coccy, rods underneath the microscope. So let's go through some typical presentations that we can see of pyaderma and some not-so-typical presentations of what we can see in pyaderma. So the first one I want to start with is actually one that I often see overlooked. And these can be really hard to sample. And that is what we call moth eaten alopecia. We tend to see that more in our short-coded breeds, so think French bulldogs, pit bull terriers, anything that's going to shorter hair coat. We often want to think of erythema crusting coming along with pyaderma when they have a secondary infection. But we can get this appearance where it just looks like little chunks of hair fur have been taken out by little moths like a little moth moth just came and kind of chewed out a little bit of your fur just looks like patchy, patchy, small, annular alopecia. These can be really hard to sample because sometimes there's not a ton of coccy under the microscope when we do sample them. My biggest, I guess, recommendation would be if you get these cases, try to sample from the edges of the lesions, very similar to an epidermal colorect, which we're going to discuss later. And really press firmly, I personally like doing direct impression smear when I have moth eaten alopecia, I like direct impression smear is most every form of selecting anyway from the skin if I can, but I do find with tape because it's hard to get a lot of material underneath the microscope. You get a lot of squames and skin cells and then it's even harder to find it. But I'm pressing pretty assertively, I'm sampling multiple areas and I'm going to look for things like at least some moderate coccy and inflammation. So I'm going to look for nuclear streaming, neutrophils, things like that to show me that it's truly something that the body's reacting to. So mothine alopecia can be a tricky one, but really try to get multiple samples from the edges of the lesions. The second presentation is just diffuse alopecia. You know, sometimes we just get diffuse alopecia. Usually you'll have some scaling and crusting that coincides with that, but some of these cases will just kind of drop their hair coat. And I actually find this in some of my long-coated breeze. And once you really part the hair that is there and look at the skin, they just look like they've got these big bald patches on them. So like my shelties and my colleagues, because we don't often see the early signs of pyadurma, because they do have such a long coat, I kind of have to like sit through the hair and actually look right at the skin. So oftentimes owners don't notice it until these just huge chunks of alopecia that are present. So really get down to the skin. Again, sample, if there is some scaling and crusting, try to get under it, but definitely collect cytology on those cases because they can look more diffuse. The next couple are pretty simple, but I just want to kind of go over some of the basics of how we can get really different presentations when we're looking at secondary bacterial foliculitis. And the next one is just irithema. So you can just get irithema, redness, inflammation. The body's just kind of making it bright red. Sometimes there's kind of some clear debris or serious anguines debris, maybe perelint debris, but sometimes they just look bright red and inflamed. And we'll blame this. Sometimes I'm all cesia, right, especially if they have an odor to them, but we can see pyadurma cause irithema. And the tricky thing about all these presentations I'm mentioning is sometimes dogs and even cats will just have one, right, we definitely see erythema and dhalapisha, sorry associated with having secondary pyadurmas, but ultimately they can have all of these things, right, they can have some crusting, some scaling, some erythema. So that's kind of what you have to really consider is you may have a pet who shows you just one of these, you may have a pet who shows you all of these. So erythema, just having erythema, we definitely see this with like erythematous plaques on cats when they have a secondary pyadurma. The next presentation, scaling, so just having a bunch of scale. And this often coincides with things like alopecia, but you don't have to have thick crusting. Sometimes you just have a bunch of scale, and it can almost look like a caretinization disorder. And I have definitely had cases that have a bunch of scaling. I find infection under the microscope and I tell the owners, you know, we may need to consider just treating the infection first, but we might be biopsying your pet. I don't know if they have sebaceous adenitis, another caretinization disorder, but then once I treat the infection, all the scaling goes away. And so then we know that it is related maybe to something like allergies. So just having really thick scaling present on the skin, or even little fine scales present on the skin can happen with things like pyadurma. The next one is one that often is mistaken for dermatophytosis or ringworm, especially by clients. Clients will come in and say, you know, oh, I'm afraid they have ringworm because they have these big circular areas of alopecia on them. And it is what you would probably classically think as ringworm in people, though we don't tend to see this presentation very often in dogs. And that is epidermal colorets. I've put this up often on social media on the Durham vet podcast. We've talked about it, but we can get epidermal colorets and that is almost always pyadurma. I'm sure you could get things like dermatophytosis and rare cases, demonocosis, you know, you want to go back to the basics of what differentials for a pyadurma can be, but oftentimes this is epidermal, this epidermal coloret is related to pyadurma. So this is essentially when we definitely want to take your direct impression smear along the edges of that lesion because it's a bacterial foliculitis. It's basically spreading. And so you get this kind of circular lesion and the more active infections on the periphery of that lesion, but often get hyperpigmented right in the middle of it from that chronic inflammatory response that's been more present in the middle as it's expanded out. So you want to sample along the edges. So epidermal colorets is kind of like a really classic sign of pyadurma, but very commonly mistaken by owners for ringworm. So you can provide some relief that it's probably just a bacterial foliculitis, but of course, we're going to cytology to know for sure. And then some more basic ones. So the next one we see a lot in that is crusting. So crusting, like thick crusting, maybe more even fine crusting. It can be focal. It can be diffuse and all over. It can be multifocal. So of course, cytology, the biggest thing with cytology on a pet that has a lot of crusts, like a cat or a dog that has a lot of crust, is to get under the crust. The crust is the body's way to protect itself. So you want to actually get under the crust with your slide so that you get a better representation and actually can find the bacteria in the inflammation that's there. Of course, for crusting dermatoses, we want to be considering differentials, like demodax, definitely dermatophytosis, especially a cat that's more diffusely crusted, but dogs as well can get dermatophytosis. And then even some autoimmune diseases. So pimpigas can look just like a pioderma, really thick crusts. If you have things like the mucous membranes involved, like the nasal plenums crusty or the pop-outs are crusty, then that would be an indication that it's probably something besides just a pioderma. The other thing to remember is very similar to what I mentioned before, is sometimes you have to treat the infection and re-evaluate, because pioderma is a secondary issue. We often see it related to allergies, but it doesn't have to be allergies. So you could have a pimpigas case that is also super infected. So we often have to treat the infection first and re-evaluate to know what the next steps are. Are we biopsying that case? Are we going to do an allergy workup in that case? So sometimes you have to clear out the infection before you really know because they can be really tricky. And with really crusty, even going back to scaly and erythema, the other thing it could be is neoplasia. So epitheliotropic lymphoma can look very, very similar to some of these infections. Again, if you have an older dog who's all of a sudden breaking out with lesions and they have the nasal plenum or the pop-outs affected or the oral cavity affected, then you should take a step back and realize that's not typical for pioderma. And there probably is something like an autoimmune disease or neoplastic disease going on, at least for a dog. Obviously cats are tricky because they get oral eocidophilic granulomas. But especially for a dog, if that's present, you should be considering something else like those two categories. But crusting can be really tricky because it can be adherent, thick. It can get lots of debris underneath. So sampling underneath that crust, looking for infection, making sure you treat that infection and then maybe reevaluate in the case. If it completely clears up just by treating the infection, then maybe we look into something like endocrinopathy's allergy workup. If you clear up the infection, there's some improvement, but there's still a lot of crusting. And when you reevaluate your cytology on recheck, the infection's gone, but there's still a bunch of inflammatory cells, then we probably should really be pushing to biopsy that case. Just to assure that there isn't something like an autoimmune disease or neoplasia there. And then the last case, and this is kind of the case that really encouraged me to make this episode. When I put this up, I got a lot of questions about it. Is another tricky short-coded breed one and that are urticarial-like lesions. So those short-coded dogs, very similar how they can get mothi and alopecia, that can be tricky, they can get what looks like urticaria. Owners come in and they're like, they have hives. And if they are short-coded like boxer-friendly, pity, all the things that have short-codes on them, I really encourage you to really take your thumbs. I take my fingers and my thumbs and I really go like kind of part the hair. You often will find kind of stuck at the base of those hairs crusting and sample them. I'm not saying urticaria and hives can't happen of horse it can. But I would say more often than not, when owners come to me saying their pet has hives and they are one of those breeds, we find a bacterial folliculitis, a pyoderma. And if we treat that, all the hives go away. What's tricky is sometimes these dogs are put on series Indian about it before they see us. And the owners say, well, the hives went away. But it was probably, yeah, there's probably inflammation there, that's true. But it's probably more that the pyodermic got treated. So urticarial-like lesions can look really tricky. I will definitely part the hair, really look at that. Really cytology the lesions. You usually find some erythemen crusting kind of at the base of that hair going into the skin. And if you sample that and see a lot of neutrophils with some coxair rods, I would treat that first and kind of see what happens. So those are some of the more basic things we can see within the representation of pyoderma. And a lot of these we talked about are more familiar in dogs. But of course cats can have some too. So to recap, mothinalpecia, especially in our short coated dogs, really try to sample from the edges of the lesion. You can get more diffuse alopecia in some of these cases as well. Just erythema scaling. That tricky epidural cholerae, you can provide relief to the owner. That most of the time you sample, you find coxai. Then it's probably due to an infection from bacteria, not from dermatophytosis. Crusting, that's a tricky one as far as differentiating between autoimmune and neoplastic cases. So do your cytology, make sure you clear the infection, reevaluate, and then urticaria-like lesions in short coated breeds. Again, really get to the skin. C-A-B-C evidence of erythema crusting. And through all of these more importantly, you're going to collect your cytology so that you have some indication of what's going on under the microscope. You know, make sure that you're assertive with your collection, get multiple areas because sometimes it is tricky to find them. But once you get more familiar with seeing a lot of these cases, you'll feel more confident about recognizing pyoderma and using your diagnostics to get to that. Lastly, there's always a reason the pyoderma happens. So if you treat a pyoderma, we still need to figure out why it's happening. So go back to many things we've talked about in the past, whether it's lab work, look for hormonal disorders, the history that suggestive of allergies, the history that suggestive something else is going on, like autoimmune or neoplasia. But to prevent the pyoderma from coming back, we need to figure out why it was there in the first place.