Hello and welcome to the online session of the World Veterinary Association Congress. I am very excited to be able to talk to veterinarians from around the world and especially from one of my favourite places on Earth, which is New Zealand. So, my name is Linnell Johnson.

I am a professor at the University of California Davis, and I've been incredibly fortunate to be able to practise respiratory medicine for the bulk of my career. So I'm gonna be doing several sessions for the group. And the first, I have to admit, is probably my least favourite topic, and that is chronic nasal discharge in the dog.

And one of the reasons this is my least favourite topic is because it's so challenging to determine what the underlying disease process is and then what to do with these animals for treatment. So I'm gonna give you some of the techniques that I have used over the course of many years to try to help me decide what the likely disease process is before I do a lot of expensive diagnostic testing and how I like to talk to the owners about what I think is the probable cause for their animals discharge. We'll also talk a little bit about treatments that can be employed in the absence of a specific diagnosis, but unfortunately, that can be quite challenging in animals with nasal disease.

So the first thing that I like to do in a patient that has nasal disease is converse with the owner about the type of nasal discharge that the animal has and whether it has been the same throughout the course of disease or whether the discharge has actually changed. One of the things we can see is that fungal diseases and neoplastic processes can start out in a unilateral fashion. But then over the course of time, they will become bilateral.

Whereas a disease process such as a foreign body or a two-ro abscess starts unilateral and usually will stay unilateral throughout the entire disease process. One of the things that I think is, is kind of surprising is that some of the inflammatory rhinitis cases that we see in dogs and cats can be either unilateral or bilateral. I think because we don't really understand what the cause of these disease processes is that helps us accept the fact that they don't always play by the same rules as some of the more traditional or the more ideologic disease processes like fungal rhinitis or neoplastic rhinitis.

I do think that the type of nasal discharge can be helpful in deciding what the disease process is. If we look at the dog in the centre with this yellow-green type of nasal discharge. One of the things I would be asking myself is, is this purely a nasal condition, or is there a chance that this dog is actually coughing material up into the back of his nose and has a pneumonia condition.

So in some cases, deciding if an animal has cough in conjunction with nasal discharge can be really beneficial. And in this dog in particular, I would do cytology of the nasal discharge, looking for the presence of eosinophils because we know that eosinophilic lung disease can affect the nose, and animals with eosinophilic lung disease can cough material up into the back of their nose that subsequently drains out the front. Now, I will be among the first to admit that nasal cytology is rarely beneficial, but occasionally, you might find something of interest.

So if I do cytology of this nasal discharge and I see rafts of eosinophils, I would be convincing that owner that we need to investigate concurrent lung disease. Now, chances are you'll just see various inflammatory cells, lymphocytes, plasma cells, neutrophils, and nothing will be very specific. I would certainly never culture nasal discharge and I wouldn't rely on cytology to make a diagnosis of fungal or neoplastic disease because unfortunately, Cytology is not a very good predictor of what the disease process is inside the nasal cavity.

Now, looking at this dog on the right-hand side of the screen, we see that he has a little bit of haemorrhage, but what's more interesting is that he has marked depigmentation of the nostril. And this is a finding that is fairly characteristic for aspergillosis. We see it in about 40% of our dogs that have aspergillosis as a cause for nasal discharge.

Now, if the discharge is purely hemorrhagic, I would start thinking about the possibility of hypertension or a coagulopathy. And one important thing to remember for that condition is that pure ripostaxis can be due to either an intranasal disease or a systemic disease. Whether it's unilateral or bilateral does not exclude the possibility of hemorrhagic disease associated with thrombocytopenia.

So that's an interesting phenomenon that we have to keep in mind with these patients. So occasionally nasal discharge will result from lower respiratory tract disease or a systemic disease, but most of the time, we're thinking about a patient having a primary nasal cause of the discharge. And unfortunately, a lot of the times, they have mucopurulent discharge in conjunction with some bits of epistaxis.

Now, for my practise, the main differentials that I'm gonna consider for that presenting complaint is aspergillosis, a neoplastic process, or lymphoplasma cytic rhinitis. Now, if the discharge is purely unilateral, it could be either of these disease processes in the early stages, or it could also be a two-root abscess or a foreign body. But those are actually not as common as those top three differentials in my practise.

So we're gonna spend the rest of the hour talking primarily about these disorders. Now, if the presenting complaint is fairly similar in these. Animals, we have to ask ourselves, is there any other piece of information that will help us discriminate among these three diseases?

Obviously, and an animal has a neoplastic process, that's gonna be a great concern to the owners. And Aspergillus is an equally expensive disease to diagnose and treat. So if we can give the owner some clues.

To the presence of one of these disease processes, I think it can be helpful. Unfortunately, a lot of the features do overlap. We've already mentioned that the nasal discharge is typically unilateral initially, then becomes bilateral in aspergillus and neoplasia.

And lymphoplasma cytic rhinitis can be either unilateral or bilateral. Certainly, we would anticipate a neoplastic process to be in a middle aged to older patient, whereas asper is in young to middle aged dogs. But in fact, all of these disease process can occur in any age of animal, and they tend to occur in dogs with long noses.

So breed associations don't help us. I do think that a really important thing to consider in these animals is the physical exam. Because if we have a neoplastic process, a mass lesion will typically cause a loss of nasal air flow.

Now, occasionally, we might see loss of nasal air flow with a foreign body, but certainly in a dog with relevant clinical signs, decreased nasal air flow is a key finding that would make me discuss serious complications with the owner. Neoplastic processes also can lead to a mass effect that travels up the optic. Channel and can lead to a loss of ocular retropulsion.

And may also lead to ipsilateral lymphadenomegaly. All of those things would make me think about a possible neoplasm. Now, in contrast, Aspergillus usually as normal to increased nasal air flow.

Both of these conditions can lead to marked pain on palpation over the top of the nose and over the frontal sinus. Aspergillosis can actually lead to lymphadenopathy as well. And in whenever this is detected on physical exam, it's a good indication to do a lymph node aspirt as part of the diagnostic workup.

A neoplastic process can be found in that local lymph node, whereas with Aspergillus, we would tend to find simply reactive lymphadenopathy. The lymphoplasmaytic or inflammatory rhinitis tends to have features of both disease, so it can abnormal to decreased nasal air flow. In my experience, it's very unusual for there to be total loss of nasal airflow as there might be with a neoplastic process.

So I use the physical exam features when I'm discussing the likelihood of these differential diagnoses with owners. Before we go to do a diagnostic workup because unfortunately, the workup of a patient with a nasal disorder. Always follows the same general path or it most often follows the same general path of blood tests to assess the animal's risk for anaesthesia, CT or skull radiographs to investigate the extent of disease followed by rhinoscopy.

So we'll go through a few cases that illustrate some of the features of this disease. This first case we've already seen, we looked at the nostril of this dog and said, oh my goodness me, this looks like a dog that probably has aspergillosis. The interesting thing about this dog was that she or he had only epistaxis, no nasal discharge, just marked nasal bleeding.

He also had such severe pain on his, his nasal plenum that he was blephrospatic and he would shy away when the owner tried to pet his head. Now, the right nostril was swollen and depigmented as we saw. This is a case that did have mandibular lymphadenomegaly.

With all the others being within normal limits. So this is a dog that is definitely gonna get a lymph node as as part of his diagnostic workup. The lympha No, no lymph node aspirin did show a reactive cytology.

His blood work was normal. I, I should comment that because this dog had pure epitaxis, we did a PT and a PTT as well as a platelet count, and we also did a buckle mucosal bleeding time before anaesthetizing this patient. And what we see in the CT is quite characteristic of a fungal rhinitis.

On the left side of this dog's nose, we see nice normal turbinates. The scrolls of bone are intact. And we have air spaces in between.

Whereas on the right side, we see a wide open space with collapse of the turbinates. As we go further back, the left side is still relatively normal. Right side is still a wide open space and we see that the turbinates have collapsed upon.

Each other and there's also mucus or debris filling the rostral nasal cavity. As we go further back in the nasal cavity, we start seeing some soft tissue densities that appear to be adhering to certain structures within the nose, and that becomes more pronounced as we go back into the frontal sinus. Again, this is the right side of the dog's head and we can see that there's an amorphous mass effect.

Filling this frontal sinus. Now, sometimes neoplastic processes will lead to a pacification of the frontal sinus, as will an inflammatory rhinitis. If we have an obstruction of the naso frontal duct, we'll see that there's soft tissue density in here.

Usually, It is either completely filled, or there will be a meniscus, which indicates that there is a fluid line in that frontal sinus. Instead, in this particular case, we get the impression of a mass effect, and this is the classic appearance of a fungal granuloma. Now, perhaps some of you are saying, well, why do I care what the CT looks like?

The only thing I have is skull radiographs. And if we go back to this first image of the CT, I think you can imagine that if you did an open mouth view of this nasal cavity. You would see an absence of turbinates on the right side and normal turbinate structures on the left side.

And looking further back in this nasal cavity and getting to the region of the frontal sinuses, if we did a frog eye view of the dog's skull, we would See that there was a mass effect filling that frontal sinus partially but not completely. Now this This type of appearance on CT radiographs really is almost pathognomonic for aspergillosis. And this is a situation where we're gonna look very closely at the curbiform plate.

So what we've done here is gone in a cross section across the curbiform plate and we're doing a coronal view where we can look Directly at that curbiform for any breaks in the, in the region. And what we see here is that the curbiform plate is fully intact. And that tells us that that topical treatment with an antifungal drug is Likely going to be safe in this patient.

Now, if we saw minor breaches in the curbiform, I would tend to warn the owner about the possibility that the drug could leak across that region and lead to neurologic sequelae. Although we actually worry about that less these days than we used to. There have been several recent studies that show that the topical treatment is safe even when there are some breaches in the curbiform plate.

So here again is a picture of a dog that has that classic depigmentation. They're usually young to middle-aged dogs that are large breed dolichocephalics, so collies, German shepherds, Rottweilers. In some cases, there might be a previous history of trauma or a foreign body, but oftentimes we're seeing animals that don't have that in their history.

Instead, they've probably aspirated a large amount of fungus and it's set a hold in the nasal cavity and has started to erode away at the nasal turbinates and grow back. Back up into the frontal sinuses. Now, if I were seeing a dog with this clinical presentation in practise, one of the things that I would be tempted to do is an auger gel immunodiffusion test to help gauge the likelihood that this animal has aspir.

Because we do know that if an animal has a positive AGID. It's highly likely that they have Aspergillus. Now, unfortunately, a negative antibody titer does not rule out aspergillosis, but if it's positive, it's highly suspicious for the disease, and we know that the animal would benefit from CT, rhinoscopy, debridement, and pretty intensive therapy.

In some instances, when we do rhinoscopy, we would do a culture of what we would visualise. So you might ask yourself, is there any value in doing a culture of nasal discharge? Well, if we look at this dog's Image, we see something that appears to be a white plaque-like lesion in the nose.

And if I saw that in clinical practise, I would be tempted to take a sample for culture. Unfortunately, if you took this red mucoid bit or if you used a blind swab to collect the sample, it's much less likely, less than 10% chance that you would find Aspergillus on culture. However, if you do culture a plaque lesion and find Aspergillus, that would be a highly specific test for the diagnosis.

I already mentioned that the imaging findings are pathognomonic for aspergillosis and certainly on rhinoscopy, we see plaque lesions that we take as indicative of the diagnosis and I'll show you some images of those. Now, we did have a few cases that came in several years ago now, where we did rhinoscopy on the animals and did not find any plaques that were suspicious for Aspergillus. So in those animals, we actually tree find the frontal sinus and we're able to identify plaques in 8 of 10 dogs.

So if you are doing rhinoscopy in your practise with something like an otoscope cone, or just a rigid rhinoscope, I'm sorry to say that this diagnosis can elude you. And there are instances where we need to do either trephination of the frontal sinus or we need to use a flexible endoscope in the nasal cavity. And sinus trephination is something that is, is not tremendously difficult to do.

It does require a knowledge of the anatomy of the skull and certainly I always feel better if I've got a CAT scan available so I can calculate the depth of the frontal sinus, but I'm just gonna review this with you in case you have cases where a trephination procedure is needed, or whether you need to explain to an owner what might happen when the animal is referred for treatment. The borders that we use for trephination are the midline of the skull and then the bone above the eye, and we're gonna go about 1 centimetre off midline and 1 centimetre above that area. We're gonna take a Jacob's Chuck and then Intramedullary bone pin to do the trephination, little stab incision, and then use a bone marrow drilling type method to do the sinus trephination.

So this video shows what we're gonna use a big I am pen and a Jacob's Chuck. We've done a surgical prep of this area. We do this in a clean room, not in an OR.

We have a stab incision and we usually let that heal by second intention, so we don't want it to be too big. Now, this is something that's important to highlight. We've put the IM pin into the chuck and we've left out only about 1 millimetre of the IM pin so that when we drill into the frontal sinus, We will not penetrate the calvarium.

So we've calculated or measured a depth where we know that a millimetre insertion of that IM pen is not going to approach the brain case. So here we place the iron pen firmly in the incision, use that bone marrow drilling motion. Sometimes it's very easy to penetrate the skull.

Other times it's hyperstatic. And then what we do in our practise is we take a, a rigid telescope and look in the frontal sinus. And this is that classic fungal plaque that we would see.

And this, I think also helps us understand how why we see that plaque-like lesion on a CT scan as we interrogate the frontal sinuses. This is just another view of, of how we treat fine. Here you can see there's a stab incision with a hole under the frontal sinus, and we've taken an image through the scope down into the frontal sinus and you see that amorphous mass effect.

And what we will then do is take a cure and scrape away at this tissue. It can take a lot of time to debride that material from the frontal sinus and we'll use aspiration and suction to retrieve that material. We might send it in for histopathology or culture just to confirm the diagnosis.

Very rarely, we will find a penicillium case, not Aspergillus. Very rarely will we do culture and sensitivity on a fungal isolate, but it's always good to collect the sample just in case. Now, this is an image of how we sometimes debride it.

We can put some biopsy forceps from Carl stores or Sotech through the hole and chip away at that material. But I wanna show you another video where we've actually taken a flexible endoscope up through the rostral nasal cavity. And we'll see lots of turbinate destruction in this nose and then we'll pop into the frontal sinus where we see a fungal plaque.

So if you have a flexible endoscope in your practise, the one we use is 4.9 millimetres. And if you gently manoeuvre your way through this tissue destruction, Notice that the turbinates are mainly gone in this animal.

And you can go up to the region of the frontal sinus and see a plaque lesion. And in this instance, we can use flexible forceps through the endoscope to debride that material and then suction that out. So that avoids the need for trephination.

Now this technique does require that there's pretty more turbinate destruction so that the scope will go up into the frontal sinus. But I think this is a nice illustration of what the mat of fungus looks like on CT compared to what it looks like on rhinoscopy. Now there've been 20 years of research and Into treatment for nasal aspergillosis and we haven't made a lot of progress.

We still do primarily topical clotrimazole treatment. One of the early studies showed that there, that this was effective in treating and controlling disease with success in 85% of the dogs. But what's important to note is that multiple infusions are typically required in dogs to control disease.

We've gone away from surgical placement of catheters to endoscopic methods of placing catheters, and what I use are right angle forceps to put the Foley catheter up behind the palate and then we'll use drug infusion catheters rotally in the nose and then plug the nose with another Foley catheter and infuse the drug under pressure. Now, because the infusion is under pressure, the drug tends to leak out. So we use a lot of Q-tips to contain the material in the nose.

We did a study here several years ago looking at this method for controlling disease in our patients and we again found that we could cure a lot of animals. But they do require multiple treatments. So about 50% of our dogs were cured after one treatment.

But several required 2 and 3 treatments and overall, the success rate was about 2/3 of our animals had resolution of disease. The other thing that we found in this study, it was unfortunately, the presence or absence of clinical signs do not predict whether the fungus is present or absent. So even when animals seem to be free of clinical signs, we can still find plaques in the nose and vice versa.

It's also of no value to repeat. Serology testing in animals to determine if the disease process has been controlled. Now, colleagues at the University of Lia recently reported a simplified procedure for infusing the, the drug and the, the medication that we tend to use is 1% clotrimazole.

We get the drug delivered in a powder and then dilute it in polyethylene glycol. The, the nice thing about this modified protocol is that we put the Foley catheter in the back of the nose to seal off the nasopharynx, rotate the dog's head into a 90 degree position, and then simply fill the frontal sinus and nose with 1% clotrimazole. And this protocol was equivalent in success to the more invasive treatment and perhaps what's more important from this study is that they did confirm the importance of debridement in managing this disease.

Now, the reason this disease process is just so incredibly challenging is because it's so extensive by the time we start to treat this, these animals. You can see that this animal has a fungal plaque right at the entrance to the frontal sinus. So whether you'd be able to see this with an otoscope cone, I think is debatable and the bulk of the fungus is up in the frontal sinus.

And this, I think also highlights the importance for debriding because the topical medication is never gonna penetrate that that degree of disease. Then we'll talk about another case with a similar presenting complaint, although this dog had only a two-week history of epistaxis and was an older dog. On physical exam, unfortunately, this dog had more facial asymmetry with exothalamus and strabismus on the left side.

And most concerning to me is that this dog has bilateral loss of nasal air flow. So this is a dog where I'm immediately going to be concerned about the possibility of a neoplastic process. And when I talk to these owners, I want them to understand that Neoplasia is my top differential, and we're going to be making a radiation mask because we know that radiation therapy is the most Likely process that will prolong survival and prolong progression-free interval.

And I, I want them to understand my concerns about their animal before we go through a lot of diagnostic testing. Now, because of the epistaxis, we again did PT, PTT, blood pressure, and a BMBT. And when we look at this dog CT as we go through this video, notice that there's a mass effect on one side and that the frontal sinuses are filled with material.

And when we get to the frontal sinuses in this dog, we see that there is marked filling of both frontal sinuses and even some bone loss in this animal. So here are some still images showing this marked mass effect rotally in the nasal cavity. Notice that we're in the region of the canines and it appears that there's a huge mass in this region, more normal on the right side.

As we go further back, we start to see that this mass has actually crossed the septum. And it's causing distortion of that region. And this shows that there's a mass lesion in the nasopharynx.

That's what's probably blocking nasal air flow and that we have some bony destruction up into the frontal sinus. And again, both of these frontal sinuses are fluid-filled and the bony destruction could be due either to an obstructive sinusitis or on this left side. It could be related to tumour effects on the bone.

Certainly, this animal has a guarded prognosis because of the facial distortion and the involvement of the bones around the skull. And here's a rhinoscopic view. If we contrast this with what we saw in the dog with Aspergillus, we see, in fact, a mass lesion that is filling the nasal cavity.

And what I wanted to highlight here is, well, we're taking a biopsy of that abnormal region specifically with our instruments. You can imagine if you took a biopsy from the inner aspect of the nose that was not not targeting the mass, you would come up with a diagnosis perhaps of normal tissue or perhaps of inflammatory rhinitis. So one of the really important things with a neoplastic process or actually any process in the nose is that we visualise the lesion and then take a biopsy.

One of the things that I always remind myself when I take a biopsy from the nose is to make an impression smear so that I can get an early idea of what the disease process might be. And this shows some very aggressive carcinomatous cell from the nose. This is an animal that had lymphoma in the nasal cavity and so, getting a visualisation of cytology can be helpful.

I will oftentimes wait for the biopsy result to come back before I tell the owners that, that it is definitively a neoplasm, but It is nice to have an early idea of what the process might be in case there's some untoward effects with anaesthetic recovery. It's rare for me to have animals that bleed excessively after a biopsy, and even when I biopsied a neoplastic process and had a dramatic drop in hematocrit, the animals still generally recover quite well. So in fact, I would say I've had more serious bleeding episodes in animals with Aspergillus as compared to a mass effect.

I mentioned that radiation therapy is the treatment of choice in these animals, and we expect median survival times of 9 to 12 months. And the main thing I tell owners is that this is a median survival time. So your dog could live 2 years and be relatively free of signs or could live only 3 months and be relatively free of signs.

These images are from an old radiation unit where we see a lot of moist dermatitis and gingivitis from the radiation beam. We don't see nearly that severe of a side effect now. In animals where we're doing stereotactic radiation therapy.

But I do wanna make sure that owners understand this is generally a, a control process. It's not a cure. And for owners who can't afford to do radiation therapy or when owners aren't willing to go through with diagnostics when there's a concern about neoplasia.

There is some palliative therapy that can help. And I've had dogs with nasal tumours who have lived quite happily for 5 to 7 months on paroxicam and and bowel. Paroxicam is a non-steroidal anti-inflammatory agent.

It generally has to be compounded for use in dogs because it comes in 10 milligramme tablets. But it's quite well tolerated. It can cause GI erosions and renal side effects, but I've had most of my dogs do quite well on this therapy.

And for dogs with neoplasia or aspergillus that have bleeding issues, union bowel or Yanow has been effective in these animals. I have owners go on to the internet and and purchase the pill form of this. Chinese herb and follow the instructions given on the packet and it can reduce bleeding.

And there have been some interesting studies on how this might work that are published in the emergency and critical care journal. Now, a novel technique for controlling nasal neoplasia that we've investigated here at UC Davis is chemo embolization. This is an image under fluoroscopy from Bill Kolp who's our one of our interventionalist surgeons here.

You can see the dog's head and its nose extending towards the right side of the of the slide. And what Bill does is feeds a catheter up to the blood supply of the tumour, injects dye to show where the branches of the artery are, and then he'll inject a drug along with some embolic spheres. So you could cut off the, the blood supply to the tumour with direct chemotherapy to the site.

Another one of our surgeons, Doctor Michelle Steffi, has done cryotherapy of nasal tumours and has controlled disease process that way. So those are some interesting interventional techniques that are, that are proving helpful in, in some animals. Last but not least, I'll talk with you about lymphoplasma cytic rhinitis and I would say that this disease process is the bane of my existence.

I rarely saw this disease process until I moved to California and I do wonder if a lot of the Disease could be related to pollutants in the environment or the air quality. You know, it's a, quite an agrarian environment where we live out here, but this disease process seems to be quite prevalent in this region. It's very frustrating to treat and unfortunately, The signs and the features mimic what we see in neoplastic and fungal rhinitis.

A former student did a nice retrospective study of the cases we've seen out here and just like all nasal diseases, they occur in large breed long-nosed dogs just to increase the amount of nasal discharge that we see around the owner's houses. Interestingly, a few of these dogs presented with pure epistaxis and all of them had been tried on various medications. Most commonly antibiotics, some steroids, either intranasal or oral or antihistamines and had shown no clinical response.

Now, interestingly, the CT findings are kind of a mixture of what we see with neoplasia and fungal rhinitis. This animal has some degree of turbinate lysis and lots of fluid accumulation, patchy flu fluid and almost a mass effect in this dog. And we do see frontal sinus involvement.

Notice that this is more of a fluid line, but You know, you could say maybe we should have find that dog to look for Aspergillus. So, that's what we have found in, in our patients. In our particular group of dogs, after we do CT and after we do rhinoscopy, we always do dental probing to look for dental-related nasal disease, and we found no CT evidence of dental disease in any of these animals.

On rhinoscopy, we see muoid discharge and mild amounts of turbinate destruction, hyperemia, no plaque-like lesions, no mass-like lesions instead just this heavy thick glue-like nasal discharge. Now, I, I mentioned to you that we have no dental disease in our patients. There was a study in the journal of the dentistry that suggested that they found a dental-related cause for inflammatory rhinitis in a, a majority of cases, but I would say that this is not Idiopathic lymphoplasmocytic rhinitis.

This is dental disease affecting the nose and so to me, this is a totally different process, but it does highlight the need to do dental probing as part of the workup of an animal with nasal disease. Now I've heard a lot of stories about what the inflammatory. Environment in the nose means, and some people will say if it's neutrophilic, that means it's bacterial.

If it's lymphoplasmaytic, it means it's immune and some early studies of lymphoplasma cytic rhinitis suggested that steroid use was curative. But remember that neutrophilic just means that there's an acute component in some situations and lymphoplasmaytic means that there's a chronic component. And when I look at biopsies in cats, I very commonly see that there's neutrophilic on top of lymphoplasma cytic.

And in fact, this disorder that we see in cats reminded me a lot of what we were seeing in dogs. And so I started using a similar type of treatment with doxycycline and paroxicam. And it also stimulated me to investigate potential ideologies in these animals.

So, first of all, why would I use doxycycline? We did some studies where we were trying to see if mycoplasma or chlamydia might be involved in this disease, and they are not. In fact, we don't think that bacteria play much of a role at all in in the canine inflammatory rhinitis, whereas in cats, we think that bacteria at least have a secondary role.

But the reason I use doxycycline is because it has these anti-inflammatory effects. It helps inhibit the generation of the extracellular matrix and inhibits the ingress of inflammatory cells and reactive oxygen species and it seems to be relatively well tolerated and some of the animals seem to respond to that. And while I don't want to be accused of using indiscriminant antimicrobials, I think that this drug can have some beneficial anti-inflammatory effects and is worth try in some animals.

The other drug that I've used is azithromycin. This is also a very well tolerated drug and the nice thing about this is that it can be given just 2 to 3 times weekly and it accumulates in respiratory epithelial tissues. So again, worth a trial perhaps on these animals.

And then this is the Feldene that I would tend to use. A 10 milligramme tablet is appropriate for a dog about 30 kg or so. But otherwise, we would need to compound this medication.

And in older animals, I would definitely be concerned about renal side effects, but it does seem to be pretty well tolerated orally. Now, what is the efficacy of this therapy? How often am I successful in this?

Well, It's hard to say. There are additional things I will try and add with these animals. One that I've used with some success is an acetylcysteine.

This is a drug that can be effective in reducing mucus. It definitely makes the mucus thinner and so the animals seem to be able to sneeze it out better. So I, I actually warn owners that they may see more nasal discharge after starting this medication because it's easier to evacuate the mucus.

So it reduces the viscosity of the mucus and it also has some antioxidant effects. The dose is not really well known. For a cat, I would generally use 150 milligrammes, whereas in, A Doberman or a Rottweiler, I might give a full 600 milligrammes 2 or 3 times daily.

And if you get your NSL cysteine from Australia, this is how it is supplied. So it appears to be some muscle creating thing for bodybuilders, so don't be taken aback by that. But it can be somewhat effective in animals.

Now, I've talked to you a bit about increasing the Evacuation of mucus. And for that reason, I do not use antihistamines because they will dry out secretions and tend to impact mucus in the nose more. Some people have suggested using intranasal steroids.

I think that it, it's worth a try, but this dispensing unit is not really very dog friendly, and the aerodog spacing chamber is designed to take drug down into the lower airways, so whether that would treat a nasal condition or not is kind of debatable. The other thing to consider is that if the nasal cavity is filled with mucus, these drugs are not gonna penetrate very well. Lastly, I'll just finish with some studies that we did in in dogs that had lymphoplasma cytic rhinitis.

We were, we're trying to look for specific microbes like mycoplasma, chlamydia, different viruses. And what we did was we looked at bacterial load in dogs that were healthy, LPR neoplasia, and Aspergillus. We found that any dog with nasal disease has a lot of bacteria in the nose.

And then we looked at fungal disease, found again, more fungus in dogs that had nasal disease and healthy dogs. But when we looked amongst those groups, we found interestingly that Dogs with aspirin had the most fungus. Dogs with lymphoplasmacytic rhinitis had a lot of fungus, and dogs with neoplasia had the least amount of fungus.

So it did raise the question. First of all, is it possible we missed a case of Aspergillus or a different fungus or these animals? Or is it possible that these animals have a hypersensitivity to fungus that is present in what they're inhaling?

And this study was done looking at the immune response in the nasal cavity of animals with lymphoplasma cytic rhinitis in yellow compared to Aspergillus in, in blue. And what we see is that there's a partial TH. H2 or an allergic type response, hypersensitivity response in dogs with LPR compared to the anti-microbe or TH1 response in nasal aspergillosis.

So, it does raise more questions about the aetiology of this disease process. Whether it's related to a hypersensitivity response. Is there a way for us to diagnose that?

Is there a different way for us to treat that? You know, some people have tried itraconazole for management of this disease process with, with some degree of success. But it is a condition that is very, very frustrating to manage, just like the condition in cats.

So that's what I had to chat with you about regarding canine nasal disease. I hope that some of these points have been interesting to you and I really hope that We're all able to get back to New Zealand and travel again soon. Thank you very much.