OK, thank you very much and thanks everyone for joining us for this webinar tonight. So the talk tonight is going to be on the approach to non-pyritic alopecia in dogs, which is a rarer presentation to the sort of alopecia that we tend to see associated with pruritus, and often it's a lot easier to work up pruritic dogs and the resulting alopecia. So the plan for the next 50 minutes or so is to initially go over a little bit of introduction, and as part of that, we do need to just do a little bit of revision of hair and hair follicle anatomy and physiology.

Which I appreciate might not be everyone's, most interesting topic, but it is very useful for us to be able to understand how the hair and hair follicle function so that we have a better understanding of what's going on when it, when it goes wrong. We'll then go on and talk about some differential diagnoses for non-pyritic alopecia. And in the second half of the talk, we'll go over how we would approach a case, which always starts off with a thorough assessment of the signalment and history, which can take quite some some time.

Moving on to the physical and dermatological examinations before embarking on some further investigations and diagnostic tests. So why is alopecia important? Well, hair loss can be a major concern for owners, and it's certainly the case for owners of breeds known for their long or impressive hair coats.

So here's just a few examples. We have the, obviously these are rather more show examples, but we have the Pulee, the lassarapso, and the shih-tzu, and you can certainly imagine that if an owner of one of these dogs noticed some alopecia, that would be quite a significant problem for them. So some of these sorts of owners may well present patients to you very early on in the development of alopecia.

But actually, it might not always be the case because some of these very long coated dogs, might actually be quite difficult to spot. If you have, alopeciic areas, developing underneath some of these longer areas, maybe these animals may present to you at a later stage. Obviously dogs' coats vary very widely.

So in some of our short-coated breeds, alopecia is normally going to be pretty obvious even from an even in an owner that's not particularly observant. So in breeds such as these, we are usually going to be seeing these types of disease processes at an early stage. Alopecia's not just important for the pet owner though, it can also be important for the dog.

And some of the alopecia conditions can be a sign of systemic disease. Others, on the other hand, are benign and cosmetic problems, so we as vets need to be able to be able to recognise these problems and differentiate them so that we can advise the owners on appropriate management. So the photo on the left here shows a dog with hyperadrenocorticism.

This dog has the classic sort of pot-bellied appearance and has a rather thin looking coat, even surrounding the area that's been clipped for an abdominal ultrasound. And the boxer dog on the right is the classic sort of presentation of a dog with canine flank alopecia or seasonal flank alopecia, and that that condition really isn't a major bother to the dog at all, and it is largely a cosmetic problem. So we need to be able to spot these different problems and and deal with them appropriately.

Hair is obviously a characteristic feature of mammals, and it serves a variety of functions for the pets. So it is, the loss of this hair is important for the for the patient. Hair obviously serves to physically protect the skin from damage.

It's also very important in thermal insulation, certainly more so in some of the longer coated breeds than others. And in some types of mammals it's involved in camouflage. And in our dogs and cats, there are certain specialised hairs that are involved in sensory perception.

Hair's also involved in the dispersal of sweat and sebum from the skin surface, and in some cases it's also important in social interactions. So alopecia can be a significant problem for the animal itself. Now hair is made of terminally differentiated keratinocytes.

No c y te s form together to form a structure of considerable tensile strength and certainly if you've ever tried to pull apart a hair, it really does take quite a lot of effort and force to do so. Hair is formed in the hair follicle, which is a complex mini organ. And this self-renews in cycles to produce new hair.

So we have this sort of what these waves of replacing old with new. And that's possible because there are a population of stem cells within the hair follicle that are involved in this regeneration. Now it's just worth saying right at the outset that hair follicle formation and cycling is a very complicated process and it is still quite poorly understood even in species such as humans and mice.

And I think it'd be fair to say that if, if, if this process was really understood very well, there'd be a lot less male pattern baldness out there. Most omnivores and herbivores have what's called simple hair follicles, and what that means is that one hair shaft exits through the follicular opening on the skin surface. On the other hand, carnivores, so dogs and cats, have compound hair follicles, which means that multiple hair shafts exit through the same opening on the skin surface.

And interestingly, sheep actually have a combination of both simple and compound follicles which contributes to their very unique types of hair coat. Now some hairs in the compound follicles of dogs and cats are large and are called primary or guard hairs. We also have smaller secondary or undercoat hairs which are present, and they're present in much higher numbers than the primary hairs.

Compound follicles consist of the primary hairs, which have an associated sebaceous gland, erective pili muscle and sweat gland. But the secondary hairs, which are these undercoat hairs, may often only have a sebaceous gland. And it's the ratio of these primary to secondary hairs that really dictates the type of hair code that we see in animals and certainly the differences that we see between our breeds.

And the ratio could be anything up to about 5 to 20 secondary hairs for each primary hair depending on breed. So here's just a very basic diagram of the hair follicle anatomy. And anatomically, the hair follicle is divided into three sections.

So the infant dibuum, which is the most superficial section. Spans from the entrance to the opening of the sebaceous gland up to the entrance onto the skin surface. Below that, the isthmus extends from the sebaceous gland opening down to the insertion of the erectopilli muscle.

And then beneath that, the inferior segment is from the insertion of the rectipi muscle down to the dermal papilla. And the infant dibuum and isthmus parts are the parts that are permanent, so they don't regenerate. It's the inferior segment deeper down that, goes through periods of growth and regression.

At the very bottom of the follicle, we have the dermal papilla, and these are the cells of dermal origin which actually secrete the chemical mediators that induce follicular development and growth. Just above those, the matrix cells, these are the the proliferative epithelial cells which actually produce the growing hair. And in amongst those matrix cells, there are the melanocytes, which are active during allergen and they produce the pigment, which then gets transferred to the hair.

So here's just a section of skin that a pathologist might look at just to give you an idea about how these hair follicles are, are placed within the skin. So right at the top we have the very, very thin epidermis. And then we have lots of cross sections, longitudinal cross sections through the hair follicles.

And right down at the bottom, we can have these, you can see the three deeply sort of coloured purple spots, which are actually the allergen growing base of the follicles. So you can see that they're really quite deep down in the skin. They're actually beneath the dermis into the subcutis.

So the hair follicles are very deep structures. And, and that ultimately is important because if you're, for example, looking for something like a follicular parasite like Demodex, that gives you an idea of just how deep you need to do something like a skin scraping to be able to find it. Now, here's a schematic diagram of, of the, of the hair follicle in even more detail.

Now this is taken from a publication in Current Biology from about 10 years ago, and this goes into more detail than we need to tonight. But it's just to make you aware that the hair shaft itself is made of three different layers. We have the medulla, which is in the middle, and that consists of cuboidal cells.

And that's surrounded by the cortex which really forms most of the strength of the hair and contains most of the pigment. Outside of the cortex is the cuticle, and this is the outermost layer of the hair shaft itself, formed of overlapping cornified cells. And this is the layer that's responsible for producing the glossy appearance of the hair.

Outside of the actual hair shaft itself, we have a structure called the inner root sheath, and that protects and supports the growing hair. And then outside of that still, we have the outer root sheath, which is basically just a continuation of the epidermis. Finally, just outside of that, we have the basement membranes.

So you can see that there are lots of different layers. The inner root sheath itself is actually composed of a number of layers itself, but that is more detail than we need to go into tonight. So hair follicles undergo regular cycles of growth and involution, as I said earlier, to replace the old with the new.

And it is worth noting that there are 3 main stages to hair follicle cycling. We have allogen, which is where the hairs are actively growing. And then following this, that is there is a stage of cathon where the hair follicle starts to regress.

And then finally there's the quiescent stage called telagen where growth stops and eventually that hair will be lost from the follicle. So here's a diagram taken from a veterinary dermatology article from a few years ago now, and it's a little bit more complicated than those three main stages, but I'll just talk you through it. So if we start at the left hand side of the diagram, we're starting off in allergen, which is the growing stage, so we start to have active growth of a hair out through the skin.

And then as we move it into the sort of 12 o'clock position, that hair follicle starts to regress, and that is into the stage of cathogen. That then moves around into Telagen, which is the resting stage. And the actual process where the hair is expelled from that follicle following the cessation of growth is called exigent.

And that can then go straight round back into annogen again or sometimes that hair follicle can remain in a rather dormant stage, a hairless follicle called kenogen. So it's just to make you aware there are these two extra stages which are sometimes found in diagrams, but the ones to remember are aogen, catogen, and teogen. Now what do these stages look like on an actual animal?

Well, if you were to pluck out some hairs from a dog, and, from with an actively grow growing coat, you will tend to see hairs that look like this. So these are allergen hairs, you can tell they're allergen because they are pigmented. They often have quite a bulbous end to them, which is normally buried deep within the skin.

Sometimes they're bent over a little bit like this hair at the bottom of the screen which looks almost a little bit like a hockey stick. And then the hair at the top of the screen shows this keratinous sheath surrounding the hair, and that's the inner root sheath. So that is only present in a growing hair and therefore you can tell these hairs are in allergen.

Quite different, we have telagegen hairs, so these are hairs that are not growing, and at some point, they will be shed. So these tend to be rather more spear shaped, so they're tapering to a point. They don't have the same degree of pigmentation, and they don't have a root sheath.

Now, as I've already alluded to, the control of the hair cycle and the understanding of that control is well it's very complicated and it's quite poorly understood. And that, that's because there are loads of different extrinsic and intrinsic factors involved in making these hair follicles go through, this cycle. And it can factors can include things like the photo period, ambient temperatures, various growth factors and cytokines.

And hormones is an important one to be aware of because as I'm sure you're aware, some of the endocrine diseases like hypothyroidism and hyperadrenalcorticism are involved in causing alopecia. So hypothyroidism, for example, results in alopecia because thyroid hormones are needed to stimulate allergen. So if we're not getting that adequate stimulation, we don't get these hairs going round in a cycle in the normal way.

Dogs with hyperadrenal corticism, so excess cortisol, well, cortisol has a negative effect on that allergen stage, so it has the same sort of effect as a hypo hypothyroidism in that we're not getting this orderly progression around the cycle. Genetics are certainly involved in progression around this cycle, because there are some animals that have much longer antigen stages, for example, resulting in much longer hair coats. Sex is important, location on the body, there are obviously certain sites on the body that have a longer hair coat than others.

Neurogenic stimulation is also thought to be important, as is nutrition and health status, and then various environmental factors as well. So it's, it's a very complicated process and there's still a lot to be learned. In dogs and cats, hair is actually replaced in a mosaic pattern.

So that means that actually neighbouring hair follicles can be in quite different stages of this cycle at any one time. And in temperate climates like the UK, shedding may occur mainly in the spring and autumn. And hair follicle activity tends to be maximal in the summer.

So why is it important to have gone through all these bits of the hair follicle and hair structure? Well, It's clinically relevant because some of the causes of nonpyritic alopecia that we see in dogs are either due to hair cycling abnormalities where we're not getting orderly progression through that hair cycle, or because of hair structural abnormalities where the hair structure where we have the cortex, medulla and cuticle type structure is affected and that can ultimately result in alopecia. So it's important to know that background.

OK, moving on to the differential diagnoses. So one of the best ways to think about non-pert alopecia is to divide them into acquired and congenital. So congenital alopecia occurs in dogs that are born with abnormal hair coats, so it's usually going to be relatively easy to be able to identify these these patients.

And congenital alopecia has been reported in several breeds and also cross breeds. It is pretty rare and in some cases it's not known if they are actual ectodermal defects. But there is this condition called ectodermal dysplasia where there is an abnormal embryonic development, and that tends to cause problems with the skin resulting in alopecia but also its appendages.

So we can have things like hair, and claw problems, sweat gland problems, and sometimes problems with dentition. Dogs are often born with abnormal coats affecting the trunk, the head, and the proximal limbs. And they can have an absence of sweat glands, sebaceous glands, lacrimal glands, tracheal glands, and even bronchial glands.

And they tend to have quite these little peg-shaped teeth. So that that's, that's typically how ectodermal dysplasia presents. We also have some congenital hairless breeds like the Mexican hairless and the Chinese crested dogs, which I certainly I don't think these are common breeds, but you may see.

In these cases, homozygotes for the mutation actually die in utero, but heterozygotes come out as these hairless dogs that we all recognise. Homo zygos with without the mutation are actually known as powder puffs. Now the latest classification is these hairless breeds are, are thought to be a form of ectodermal dysplasia because they too can often have missing or abnormal teeth.

But in these particular dogs, sweat glands are not normally affected. So all of these sort of congenital type presentations are going to be very rare, but it's just important to be able to recognise that they do occur. Much more important for us as practitioners on a day to day basis is to be able to think about acquired alopecia in dogs.

These are the sorts of cases that are going to be presented to us in the clinic with an owner concerned about developing alopecia problem. So this diagram lists and tells you that the most important main categories of disease that can result in non-pyritic alopecia. So starting up at the 12 o'clock position.

We have the infectious causes. These tend to cause folliculitis. Bacterial folliculitis obviously being extremely common in dogs, but parasitic folliculitis, demadicosis, and dermatophytosis are also relatively common and need to be on the list.

And this mania is certainly something that's less of a concern for us in the UK, but we are seeing lots of animals with a travel history, so that needs to be on the list. Moving around the chart, in a clockwise fashion, endocrine causes, can certainly, affect that cycling, through the normal hair cycling needs to be on the list. There are various forms of follicular dysplasia which can either be linked to the animal's coat colour or not, so some of these may be relatively well recognised, such as canine or seasonal flank alopecia, whereas we can get much rarer conditions such as black hair follicle dysplasia, and colour dilution alopecia.

There are a number of immune mediated conditions that will result in nonpyritic alopecia. This list on the left of the screen here is not exhaustive, but it does include some of the main ones, and it's just important to always remember that we can get a mediated attack of the hair follicle. And then finally we have a group, a miscellaneous group, where we have various conditions that don't really fit nicely into a particular category, and one would be neoplasia, so epitheliotrophic lymphoma can certainly result in alopecia in some cases.

And in some of these other conditions we'll go on and talk about in a bit. Another way to think about non-protic alopecia is that we can have groups of diseases that damage the hair or the hair follicle, so infiltrating into the follicle, whether that be a bacterial infection or an immune mediated attack or a neoplastic infiltrate. So something infiltrating and damaging the hair follicle causing alopecia.

Or the types of diseases that cause failure of hair growth, and that can either be due to a cycling problem or a structural problem. So we're now going to go on and talk about the approach to a case. So as with all dermatology patients, establishing time and setting it aside to do a thorough history is really very important.

And I do appreciate if you're in a busy clinic with a 10 minute consult time, it's going to be difficult to do this, but certainly if you can spend a little bit of time reading the animal's history in advance of calling the animal in, that can sometimes give you really, really useful clues that may well be very important in terms of narrowing down that list of differential diagnoses. Now I know this talk is on non-pyritic alopecia, but certainly one of the most important things to initially confirm is that the animal is genuinely not pruritic because pruritus is a much more common presentation. And even if the owner thinks the animal may not be pruritic, some dogs may show this sign rather secretively.

And therefore, I think if it's not particularly obvious, I think performing a triogram or plucking some hairs and looking at them under the microscope can can help to give you a bit of further information. So this picture here on the right-hand side of the screen. Just shows a hair in the middle of the screen that doesn't taper nicely to a point, which is what a hair should look like.

You can see that it's got a rather frayed appearance, and this could quite easily be consistent with a dog chewing at this hair, causing or causing an alopecia catch. And if pruritus is present, well then that needs to be investigated first, and that's usually going to be due to parasites, infections, or allergic disease. The age and the time of onset are one of the first things to try and establish.

And that's important because many diseases have a predictable age of onset and knowing that age of onset can really narrow down that list of differential diagnoses. So if you're presented with an animal that's alopeciic at birth, well certainly that's going to make you think, could this be a case of congenital alopecia or maybe even something like ectodermal dysplasia if there's signs of things like abnormal teeth. In young dogs, well, certain conditions tend to come on, such as pattern alopecia.

Pattern alopecia, it usually comes on between the ages of about 6 to 12 months, and, will often affect areas of the body, like the ear pinny. In breeds such as dachens. Demiosis, usually a disease of young dogs in the 1st 12 months of life, if you exclude those adult onset cases, and that needs to be on the, on the list for young dogs, definitely.

And in older dogs in their middle to older years, I would have things like endocrine diseases and follicular dysplasias on the list. Follicular dysplasia, it's quite a broad category because some of them can develop as early as 3 months, whereas other, others tend to have more of an adult onset. So it's, it's, they need to be on the list, for, for certainly for older dogs, but also in some cases for younger dogs as well.

We need to know about the timing of the alopecia because some conditions develop after stressful events or drugs. So the condition telagegen effluvium, which was in that miscellaneous box on the differential diagnosis slide. It is a condition that tends to follow stressful physiological events such as non-specific disease or in some cases surgery or even things like pregnancy and lactation.

And in this condition, we tend to see alopecia developing a couple of months after that stressful event because the hairs are synchronously going into the resting stage and then ultimately falling out. Now once that once that trigger has has passed, those hairs then synchronously pass around into the growth phase antigen, and it normally spontaneously resolves. Allogenoeffluvium, which is another miscellaneous alopecia condition, tends to follow a few days to weeks after an insult such as a cytoplastic drug, cytotoxic drug, even, sorry, and drugs such as doxorubicin, for example, can cause this type of reaction.

It's always important to quiz the owner, but also have a look in the history in terms to see whether there have been any history of injections given at the site of alopecia or sometimes even just prior to the onset of a more generalised presentation because alopecia can be associated with certain injections, rabies vaccination particularly can cause focal alopecia. Which can develop as much as 2 to 6 months following injections and can can sometimes persist for as much as months to years after that injection. And then we can also sometimes see focal alopecia at the site of corticosteroid injections as well.

Now not many of the non-poritic alopeciic diseases actually are infectious, but it's still important to quiz owners on whether they have been affected with lesions or whether any intact animals have been affected with lesions. So here is a picture of dermatophytosis in a human, and that's probably the main infectious cause of of alopecia that we need to be concerned about. And here on the right hand side is a picture of some hair plucks where I have we focus not so much actually on the hair structure itself but more on the fuzzy appearance of the little circular arthrospores which you can see just overlying this hair on the left hand side's cortex.

So that fuzzy appearance is because these hairs have been invaded by damatophytes and just beneath the black band of the medulla, you can actually see the wavy appearance due to hyphae within these hairs. It's also worthwhile reviewing the animal's ectoparasite treatment history. Because if drugs such as the oraliszoxazolines, for example, or oxidectin have been used regularly, then a condition like dermadiosis is probably unlikely.

But just a word of caution in that the use of these drugs doesn't necessarily completely mean that the animal in front of you will not have demidiosis. Now there are lots of breeds that are predisposed to different alopeic conditions. So although we are taught not to pattern spot, it is important to recognise that some of these breeds that we see are prone to certain alopecitric disorders.

So examples would include the hairless breeds, obviously, so things like the Mexican hairless and the Chinese crested dogs which have been bred for that genetic mutation resulting in this presentation. Alopecia X is an interesting condition which is quite poorly understood that can mimic endocrine alopecia. It's probably caused by genetic factors and hair follicle receptor abnormalities, but the exact cause at the moment remains elusive.

It tends to be seen mainly in Pomeranians, quons, and Malamutes, and this picture at the top right-hand side of the screen is a Pomeranian with alopecia X. Dogs tend to lose between the ages of about 1 and 10, so a very variable age range, and both sexes can be affected regardless of neuter status. In this condition, primary hairs tend to be lost first around the neck, thighs, and tail.

And the head and legs bizarrely are usually stared, so the loss of the primary hairs often makes these dogs take on a rather puppy-like appearance because they they have these secondary hairs mainly over the trunk, but with time those secondary hairs are lost as well. Now pattern alopecia, which I've already talked about briefly, it tends to be seen in breeds like dachshunds, greyhounds, wickets, and chihuahuas. This also has an unknown aetiology that genetics are likely to be involved, hence these breed predispositions.

And it's a progressive alopecia that starts usually before the age of 1, so it's seen in young dogs, and there are two main forms. We have a ventral type and an ear pinal type. The ventral type tends to cause alopecia on the ventral neck, the chest and abdomen, sometimes on the cordom medial thighs and perineum.

And the pinal type tends to affect the convex ear pinny. And if you take biopsies from these dogs, histology shows that we're getting a miniaturisation of the hair follicles, creating the look of alopecia. Canine fan alopecia or seasonal fan alopecia is something that I'm sure you're all very familiar with.

It's not uncommon, tends to be seen mainly in breeds like boxers and Airedales. Here's just the, the picture on the bottom right of the screen shows canine flank alopecia. Tends to be called canine flank alopecia rather than seasonal or cyclic flank alopecia now because not all cases are seasonal and not all of them are cyclic.

And then sebaceous adenitis is a disease that's worth being aware of as well. The exact H Hology of this is also unknown, but it results in an inflammatory attack at the sebaceous glands. Dogs present with scaling, crusting and alopecia, often starting around the head and trunk, and the coat becomes very dry and dull.

And we tend to see that mainly in breeds like poodles, Akitas, and bizlers. There are also certain breed associated follicular dysplasias which are generally generally pretty rare, partly because some of these breeds are pretty rare, but we see this in curly coated retrievers. There's a picture down at the bottom right of the screen here of a curly coated retriever with alopecia, Irish water spaniels, and also Portuguese water dogs, and the top right end of the screen is probably demonstrates the most famous Portuguese water dog on the planet, the Obama's dog.

As a general rule of thumb, small breed dogs are probably a bit more prone to developing hyperadrenocorticism, whereas we tend to see hypothyroidism more in large breeds as a general guide. Coat colour can also be important in predisposing to certain alopecia conditions. So you may well have heard of the condition colour dilution alopecia.

Coat colour dilution is a pigmentation phenotype due to defective transport of melanosomes, leading to pigment clumping within the hairs. And there are actually more than 20 breeds that can have dilute coats. And it's important to recognise that not all dogs with dilute coat colour mutation go on to develop colour dilution alopecia.

Colour dilution alopecia is only only forms when these pigment clumps are are so large that they then disrupt the integrity of the hair shaft and result in alopecia. Colour dilution amnesia tends to come on between the age of about 3 months and 3 years, and it only affects the dilute areas of the of the coat. So here's a Yorkshire terrier here, and you can see that the, the face and the distal limbs are not affected to the same degree.

So Dobermans, dachens and New Yorkshire terriers tend to be affected by that condition. A rare condition of black hair follicle dysplasia. It's rather similar, tends to affect dogs with black coats, as the name suggests, and it's very rare.

And then, there's also a very rare condition called follicular lipidosis, where there are lipid deposits that get, put down and laid down within the hair shaft, and that's only been reported, in Rottweilers so far. Most of the dogs that we see in a clinical setting have been neutered, but it's really important to note that animal's sexual status if you're dealing with a dog with non-pyritic alopecia, because hyper estrogenism can lead to non-pyritic alopecia. And we can see that in intact males due to testicular tumours.

That's why it's so important to palpate the testicles in any entire male dog presenting with alopecia. And intact females can develop this due to ovarian cysts or tumours. Now in males, we tend to see clinical signs of feminization, so we see gynecomastia, a nipple enlargement, sometimes a pendulous prep use, and other dogs can be attracted to them.

And then a very characteristic skin lesion is called linear preppecial dermatosis, and this is seen in hyper Easternism of male dogs. And this is where we get a pigmentation change extending from the prepucial opening to the scrotum along the ventral surface of the prep use. And the exact cause of this is unknown, but it is seen in hyper estrogenism of males.

And if you see this band of pigmentation extending along the ventral abdomen like that, then you need to be very suspicious for an oestrogen problem in that male dog. Some of these dogs, male dogs, can also develop a problem called macular melanosis, where we get hyperpigmentation, flat hyperpigmentation, which is what macular means, on the ventrum and around the sort of perineum area. So that's also sometimes seen in, in, in, in cases of oestrogen excess in male dogs.

So unusual lesions, but just worth remembering that they can be linked to hyperestrogenism. Intact females can develop nipple, mammary gland, and vulval enlargement. And hyperestrogenism generally can result in changes of the skin, se changes of the skin, and comodomes or blackheads.

And some of these female dogs can present with prolonged stress and irregular cycles. So this is why, taking a thorough history and performing a thorough examination is so important to be able to recognise these sorts of signs. So here's the first poll question for you, and the question is which of the following would not typically be seen in hyper estrogenism of.

Male dogs. OK. The votes seem to slow down now.

So we have at 12% picking the first option, linear prepuilar erythrima. 8% pendulous prepu, 68% with cutaneous atrophy, and then 12% with gynecomastia. OK, so the majority, the 68%, are correct in this case.

So the linear prepual erythema or linear prepuil dermatosis, that pigmentation change is a very characteristic feature. Pendulous prep use certainly can be seen in male dogs with with oestrogen excess, and so can gynecomastia. Cuttaneous atrophy would be more typically seen with hyper adrenal corticism, so that's the correct answer in this case.

We need to establish the progression of the alopeciic problem. So a slow progression would be more in keeping with a systemic problem such as an endocrine disease or potentially a follicular dysplasia. Some conditions can have very clear cyclic episodes, and the main one that we tend to think about would be the canine or seasonal or cyclic flank alopecia, depending on which name you choose to give it.

And then some conditions can have more of a waxing and waning type of presentation, and alopecia areata, which is one of the immune media or autoimmune conditions whereby we're getting inflammatory attack of the hair bulb, which actually results in a almost like a swarm of bees type presentation on biopsy, which the histopathologist will tend to report on that can wax and wane. There are a couple of other conditions that can be associated with spontaneous improvement as well, and that would be conditions like telagen and allergen effluvium if the inciting trigger is no longer still present. And some of the breed associated follicular dysplasia, some of those seen in breeds like the curly coated retriever, the Portuguese water dog, can also sometimes improve from time to time.

Now, many of the non-poritic alopecia conditions will not cause signs of internal disease, but some of them will, so we do need to factor that in in terms of our history taking. So certainly if you had signs such as polyuria and polydipsia and polyphasia, that would be suspicious for hyperadrenal corticism. And then some dogs with hypothyroidism will present with signs such as lethargy, weight gain, and heat seeking.

We need to look at the drug history and also if any drugs have been given as treatments, assess the response to those drugs as well. So steroids, corticosteroids, both endogenous and exogenous, are notorious for causing Cushing's syndrome. And as I mentioned earlier, Excess corticosteroids affects the hair cycle by inhibiting allergen, so we're not getting orderly progression through the hair cycle.

If there's been a history of cytotoxic drugs such as doxorubicin, maybe that animal's being treated for an oncological problem, then that could be suspicious of something like aogen effluvium. Had there been a history, has there been a history of vaccines, especially rabies vaccine that can result in focal alopecia, and, and, and, and you need to sometimes you need to look quite a long way back in the history to look for things like this, as I said, something like the rabies could be developing months after the actual injection. And in response to drug therapy is important to assess, so some of these dogs will have been given supplements of thyroxine, for example, thinking they could be hypothyroidism.

But if, for example, there's not been any hair regrowth after several months of thyroxine supplementation, well, that probably means hypothyroidism is a very unlikely cause. As I've already slightly touched on earlier, the regular use of a product such as an oraliszoxazoline would, in my opinion, make demadicosis much less likely. Now moving on to the physical examination, I think sometimes in dermatology patients, it's so easy, particularly if you're a bit tight to time, to just focus on the problem that's in front of you and start doing diagnostic tests for the alopecia.

But it is really important to Remember to perform a full general physical examination on these patients. You may detect signs such as a pendulous abdomen. You may be able to palpate hepatomegaly, or maybe that animal has been panting excessively throughout the consultation, all of which might be in keeping with hyperadrenal corticism.

Bradycardia and weight gain could certainly be features that you might detect associated with hypothyroidism. And then these features associated with oestrogen excess we've already talked about, but gynecomastia testicular asymmetry, possibly because of a tumour, a pendulous prep use can all be seen in males, and a nipple, vulval, and mammary enlargement can be seen in hyperestrogen or females. So we need to look for clues of a systemic disease process when doing that physical examination.

So here's another poll question for you. So which of the following alopecia conditions tends to cause loss of primary hairs and retention of secondary hairs in the early stages? OK, so it's slowing down a bit now, so we'll end that poll.

So 10% of people have gone for alopecia areata, 55% with alopecia X, 5% bacterial folliculitis, and 30% with telagegen effluvium. OK, so the majority in this case, the 55% are, are, are correct in this case. So it's, it's quite a, a, a characteristic feature of alopecia X where we get the loss of the primary hairs.

And retention of the secondary hairs, which tends to make these dogs take on a rather puppy-like appearance of their trunkal hair in the early stages, and eventually the secondary hairs will be lost as well. In the other conditions mentioned here, there doesn't really tend to be quite this the distinction, and we tend to get the loss of all of the hairs really associated with those conditions. So it's alopecia X is is is is reported to be more linked with that feature.

OK, so moving on to the dermatological examination, one of the first things to try and establish is the pattern of hair loss, whether that be a focal problem, a multifocal or patchy problem, or in some cases a diffuse problem. And that's, that's really important because it can really, really help narrow down the list of differentials. Infections, so bacterial folliculitis, temadiosis, dermatophytes tend to be more focal or multifocal, causing patchy or rather moth-eaten patches of, of alopecia.

Whereas endocrine diseases and hair cycling abnormalities and follicular dysplasias tends to be more diffuse. Some diseases have very characteristic distribution patterns and don't really fit into the classic sort of focal multifocal diffuse, very well at all, but pattern alopecia would be one of those. So we have the ear pinel type of presentation and Just the bottom right hand picture of the screen here shows a dog with pattern alopecia where we're getting just alopecia really restricted to the convex aspects of this dog's ear pinny, so a very, very bizarre and quite unique type of presentation.

And then another example would be flank alopecia, where we tend to get these islands of what's called, what we tend to describe them as geographical type alopecia, where we're getting quite well demarcated patches with relatively normal head skin adjacent to that. We need to look at the skin carefully and see if there are, there's evidence of inflammatory lesions. So you need to ask yourself, does this skin look inflamed when looking at these patients?

Because if the skin is inflamed, then that would be more in keeping with a folliculitis or potentially an immune mediated problem, or I suppose also certain types of cutaneous lymphoma could also certainly look inflamed. Non-inflammatory problems would make you more suspicious for endocrine diseases, follicular dysplasias, pattern alopecia, and then, conditions like tagen and allogen effluvium as well. You need to look for primary and secondary skin lesions.

If the, if the, if you're established that the skin is inflamed, look at what's actually going on in the skin. For example, are there papules present, pustules, crusts, scale, comodomes, or blackheads? Or is there follicular casting present?

A follicular casting is where you're getting little bits of caratinous debris attached or matted onto the hairs, which can give you a pretty good clue that there's something abnormal going on with those hair follicles. Papules and pustules would make you think of things like bacterial infection. Comodomes or the blackheads are quite characteristically seen in demadicosis, in some cases of hyper estrogenism, and also in hyperadrenocorticism.

And the follicular casting that I just mentioned where we're getting the caratus material on the hair shafts, that is seen in demodiosis and in the conditions sebaceous adenitis. Some conditions will cause coat colour change as well. Focal brown discoloration is something that I'm sure you will see on a day to day basis and it's usually due to licking.

So that goes right back to the start of the presentation, where we need to be suspicious initially that the animal may actually be pruritic. And if it's, if it's, if you don't perform a trichogram to look for fractured hair shafts, it might actually be just pretty obvious that the animal is licking from the ground discoloration. We sometimes get diffuse lightening of the coat associated with endocrine diseases.

And a peculiar feature that's sometimes seen in alopecia areata, which if you remember, is that immune mediator autoimmune to be more precise condition where we're getting inflammatory attack at the hair bulb. If you remember, that's where the matrix cells and the melanocytes are because of the inflammation targeting the bulb of the hair, we can get pigmentation abnormalities, so we can get focal regrowth of white hairs after this condition. The skin colour can also change, so hyperpigmentation is on its own a very non-specific type of presentation, but we do tend to see it quite, quite often in canine flank alopecia, as shown in this picture down here at the bottom right hand side of the screen where we've got a large patch of alopecia with very normal looking hair surrounding it, which is quite characteristic of flank alopecia, and it's very deeply pigmented as well.

Dogs without alopecia X, the Pomeranians and the so forth, can also be so can also be seen with a very hyperpigmented skin. But it's just worth mentioning that hyperpigmentation can be seen in virtually all inflammatory skin diseases, so on its own, it's not a very useful clue. Right, now moving on to the diagnostic tests.

So when you think about diagnostic tests for that, this alopeciic dog in front of you, it's important to go back to remember the list of differential diagnoses because whenever we do diagnostic tests, we, we're, we're doing that because we already have a list of differential diagnoses in our mind, which hopefully has been massively refined based on a thorough history and examination. So, looking at this, we often are starting off with initial in-house diagnostic tests looking to either rule in or rule out the infectious causes of alopecia, which is the box at the 12 o'clock position. So diagnostic tests are usually required, and even though you may have done the most thorough history, physical examination, and, assessment of the animal's signalment, etc.

It is usually not possible to make a definitive diagnosis without performing some tests. So these are the sorts of tests that are often appropriate, so skin scrapings looking for parasites like demadiosis. Hair plucks which also look for demodex mites, but will also help look for signs of dermatophyte infection.

And I'll talk about hair in a bit, a little bit more in a second. You may, perform a wood lamp examination if dermatophytosis is high on the list. And that could well be followed up with a fungal or damatified culture, depending on the outcome, of that wood stamp examination.

Annual index of suspicion, and in surface cytology, which would be the best test to look for signs of bacterial folliculitis. Would also often be part of the, of the workup. So the final poll question of the talk is, what is the best way to sample the skin for cytology to diagnose superficial pyoderma when pustules are not present?

OK, it seems to slowed down now. It's a bit of a split on this question. We have 16% going for skin scrapings, 32% with direct impression smears, 24% biopsies, and 28% tape impressions.

OK, so yeah, I am, I asked this question partly because it's a little bit more controversial and it's not quite so clear cut in terms of answer, but skin scrapings on this occasion would not be the correct answer. Skin scrapings would be looking for ectoparasites essentially because we're looking in oil for those things, so big things in the world of microscopy. So that wouldn't be a very good way of looking for yoderma.

Biopsies, whilst a pathologist can see signs of folliculitis and bacteria on histopathology, that would normally not be a particularly appropriate way to diagnose them. It's certainly quite invasive, so that wouldn't be my answer on this occasion. Now direct impression smears, which 32% went for, would be often quite an appropriate sort of test if the skin lesion was particularly moist, so something like a hotspot type lesion or an oozing type of lesion that may well be very appropriate.

But I suppose generally speaking for most presentations or The skin, actually a sticky tape impression is usually the best way of picking up surface debris and signs of bacterial infection and then analysing that under the microscope. So I suppose in this particular case, I don't think you're wrong to say direct impression spheres, but I think on balance, I think the answer here would be, would be a tape impression most of the time. OK, and I, I just also already mentioned hair plucks, but they are one of the most useful tests to perform in any alopeciic patient, and that's because they provide so much useful information.

So they provide information on the cycling of the hair. So if you look at the, the bulb area of the hair, which I showed you pictures of earlier on with the allergen and the teennogen hairs, that can give you information about whether the hairs are cycling in a normal way. Now it's really important to not get too fixated on the ratios and seeing the numbers of telagen versus allergen hairs because that is completely dependent on breeds, species, time of the year, all these sorts of things.

There's loads of things that could influence that. But it does give you some idea about whether there is, there are signs of growth. Head plucks can also give you clues about iatrogenic damage to the hair, so again, I showed you those that head had a frayed, damaged end from from chewing.

It will give you clues about the presence of follicular parasites like Demodex. And also damatophytes. So here top right of the screen here is another example of a damatophyte infected hair.

And unlike the hairs I've shown you earlier today and also a bit unlike the hair but directly beneath it, we've lost that normal cortex and medulla definition. So this hair looks rather fuzzy at the top right hand side of the area of the screen. And again we've got those little circular arthrospores on the outside of the hair shaft ready to infect the next hair or the next animal.

And hair plucks will also give you really useful information about the hair structure. So bottom right of the screen here is an example of a dog with a diluted coat, and the bottom left of the screen is a dog with colour dilution alopecia. So you can see that the pigment clumps in this dog, dog's hair on the bottom left of the screen are far larger than the one on the bottom right, and you can imagine that once those pigment clumps get big enough, they start disrupting the integrity of the hair.

The picture at the top left of the screen shows a follicular casting, so we've got lots of brown carattinous bits of debris stuck on these hair shafts, and that could quite easily be seen in something like sebaceous adenitis or demadiosis. Now if a systemic disease is suspected, and that will usually be based on your examination, history, etc. Then.

Blood testing and urinalysis may well be indicated, from the outset, and usually it's appropriate to perform a complete blood count, serum biochemistry, and urinalysis to investigate further. And based on those results and your clinical suspicion, further testing may then be appropriate for specific conditions. If hyperestrogenism is suspected from the outset, it's important to look for signs of testicular tumours or ovarian cysts or tumours, and therefore ultrasound examination may well be needed.

And although skin biopsies is usually put last on most diagnostic test plans, it is important to note that it's not always going to be the last test that you do. Because if your index of suspicion is very high from the outset that you've got a condition that relies on a histopathological diagnosis, such as something like a follicular dysplasia of a curly coated retriever, or maybe that animal has beautifully symmetrical flank patches, patches of flank alopecia that are hyperpigmented and well demarcated, maybe that dog has canine flank alopecia and biopsies need to be done quite early on. So do remember that biopsies are often a very important test to diagnose many of these conditions.

So, just about finished on the hour mark, the conclusions are that there are many causes of non-pytic alopecia, and we do need a methodical approach to these cases. We must start with an assessment of the signalment and the animal's history, and that's followed by careful physical and dermatological examinations. And if you do that carefully, it can really help to refine that list of differential diagnoses which from the outset, just looking at that on its own can look a little bit daunting.

It can really, really help guide the most appropriate diagnostic tests to then perform. It is worth noting that not everything will have a treatment. There are lots of conditions.

Many of the follicular dysplasias will not have treatments, and therefore owner education is often quite important, and that's really, it shows you the importance of getting a firm diagnosis so that we as vets can then advise these owners on the most appropriate sort of prognosis. Thanks very much for listening. Thank you, John.

That was excellent, very informative, very detailed. I'm sure everyone thoroughly enjoyed that. To the attendees, if you do have any questions for John, we have a little bit of time that we'll try to get through a couple.

There haven't been any submitted yet, which is potentially testament to the, the great detail you've gone into, John. So just see if any pop up in the next minute or two. Otherwise, we will say good night.