Podcast: Vaccinations in Atypical Veterinary Patients with Dr. McArdle

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In this episode, host Alyssa Watson, DVM, is joined by Tamara McArdle, DVM, DABVP (Canine & Feline Practice), to discuss her recent Clinician’s Brief article, “Vaccinations in Atypical Veterinary Patients.” Dr. McArdle shares key considerations for assessing vaccination efficacy and risks, including patient health, immune response, and the impact of various medications and anesthesia. She also covers how to manage both common and uncommon vaccine reactions, as well as strategies for addressing client concerns about vaccination safety.

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Episode Transcript

This podcast recording represents the opinions of Dr. Watson and Dr. McArdle. Content, including the transcript, is presented for discussion purposes and should not be taken as medical advice. No guarantee is given regarding the accuracy of any statements or opinions made on the podcast. The transcript—which was prepared with the assistance of artificial intelligence—is provided as a service to our audience.

Dr. Watson [00:00:10] Hey, everyone. Thanks for joining us for another episode of Clinician's Brief: The Podcast, where we get to explore the conversations behind our clinical content. I'm the host of this program, Dr. Alyssa Watson, and my guest today is Dr. Tamara McArdle. She's an associate veterinarian at Albuquerque Cat Clinic, and also she's a relief veterinarian in general practice in Albuquerque, New Mexico. And so we have that in common. I also do some relief shifts several times a month at some clinics here around Las Vegas. Today, we're going to be talking about a common challenge in general practice, and that is assessing vaccination risk, especially in some of these kind of atypical cases. And so we're going to be talking about a lot here today. These cases are going to be things like young dogs and cats with acute injuries or infections that present and are due for their vaccinations, all the way to things like older pets with chronic but stable conditions or even potentially animals that have had life threatening history of vaccination reactions or autoimmune diseases. So we really want to stress that we can't create a one size fits all protocol for these scenarios. But what we want to cover today is kind of these key considerations for making a plan when we're vaccinating pets when they have other health concerns. So thank you so much for joining us today, Doc. I am sure this is going to be such a great conversation, and we're just thrilled to have you here.

Dr. McArdle [00:01:40] Thank you so much for having me.

Dr. Watson [00:01:42] Yeah. Before we jump into this really important conversation, I would love it if you would just give our audience just a quick little bio, you know, a little bit about your background.

Dr. McArdle [00:01:53] Yeah, I am a 2007 veterinary school graduate. I graduated from the University of Illinois. I practiced for several years in the Midwest. I spent most of a decade in upstate New York. And now I've been living in the Southwest for the last six years. My husband jokes that we haven't made it to the Pacific Northwest yet. But I feel like I've had a lot of opportunities in my career to work in different regions and with different people. I worked in a lot of different settings, including primary care and emergency and shelter medicine, in spay neuter and all of these areas where honestly, vaccine decisions come across almost every area of practice. I think it's not something that we can avoid at all. But I also feel like sometimes it's something that we aren't totally prepared for. And especially thinking about how many patients we have come in, who are coming in and the appointment says exam vaccines, and then they come in and they say, but what about this and this and this and this and this and this? And then we're stuck making all of those decisions at once, sometimes very quickly.

Dr. Watson [00:03:04] Yeah, absolutely. That's a great point. So let's talk just a little bit about kind of these two main considerations. You put up these two key points when we're talking about an animal's ability to even like respond to vaccines and mount an immune system, or mount an immune response, and then as well as the potential for an adverse reaction. So those are kind of like the two key things that we want to talk about first when we're developing a vaccine protocol for a specific patient. So could you just kind of like briefly explain both of those to our audience?

Dr. McArdle [00:03:42] Yeah. So in the article, I talk about these two big questions that we have to address. And I think in reality, we all know there's actually three big questions we have to address. The third question is, does this patient actually need this vaccine, or how much do they need this vaccine? Our decision is going to be really different, for example, in a three month old puppy who has never had a parvo vaccine before, compared to in a 12 year old dog who has been really diligently vaccinated on schedule every three years through life, and probably does still have some residual immunity from that. And that consideration I feel like is a little broader. I feel like we could talk about that for a whole hour as well. But we do want that in the back of our head too when we're thinking about these situations. So the first question we need to ask if we have an unhealthy patient who comes in is, is this patient actually capable of mounting an immune response to this vaccine at all, right? A patient who is severely malnourished or otherwise has a compromised immune system, even if the vaccine is safe for them, it might not work. And so we do have to think about all of the things that might be going on in their body that affect their immune system. And to some extent, I think you can think about how well can that patient respond to infections, right? If you're looking at this patient and you're saying, I'm concerned that in the situation they're in, their immune system is not going to be able to mount an appropriate response to normal infections that they're exposed to, then odds are that that patient's immune response is not going to mount an appropriate response to a vaccine either. The second, the third question here, is this patient at increased risk for adverse reactions? That is such a multifactorial issue. In particular, we're thinking about the patient's individual history of health conditions, if they've had previous unwanted reactions to vaccines before, in what situation did those things happen, what is the breed of the patient, what is the size? And there's a lot of information actually out there as far as patients are at highest risk for adverse reactions.

Dr. Watson [00:06:07] That's a wonderful way to think about the mounting immune response. If they're already having trouble or they can't deal with an infection, putting a vaccine on top of that might not be the best idea. I was wondering how important is the type of vaccine in that particular situation, if an animal is immunocompromised or something like that, are we going to think about the different types of vaccines like killed versus live versus recombinant differently because of how they stimulate the immune system?

Dr. McArdle [00:06:42] It is important to think about that as far as in particular modified live vaccines. I'm going to preface this and say that I think a lot of this is a little bit academic because our modern vaccines are very safe, right? When we read about issues with modified live vaccines causing disease, the majority of those issues are with older vaccines and historical vaccines. It can happen with our modern vaccines. The concern is that if we're taking a live virus, right, live parvovirus, for example, or a panleukopenia virus, we're then attenuating that virus, we're modifying it and altering it so that it's not as virulent as it used to be, but it's still live virus. And so there is a worry that if we put that live attenuated virus into a patient whose immune system is not properly capable of responding, then could that virus actually cause disease? Could we cause the disease we're trying to prevent? It physically can only happen with modified attenuated live vaccines. This physically cannot happen with killed vaccines or recombinant vaccines. And so there's not very many vaccines where we actually get that choice. I think the one where we have the most choice is with our feline RCP vaccines. There is a killed commercially available RCP vaccine available for cats. There also is some controversy as far as which type of vaccine is more effective, and I'm going to leave that for a different hour.

Dr. Watson [00:08:33] Yeah, I understand. So let's talk a little bit about, like, looking back, medical history of the patient, you kind of touched on this, you know, what parameters or aspects of medical history are really important when we are figuring out, like you said, at that time of the appointment, are we going to vaccinate this patient today?

Dr. McArdle [00:08:56] Yeah, I'm going to answer that question from a technician perspective, actually, because I feel like for us as doctors, when we're doing our annual physicals, we're doing a very full assessment. Most of the time we've at least read or skimmed through the vast majority of this patient's history. We've done a really full physical exam. We have a really clear idea of everything going on with that patient. The real challenge with this sort of screening comes for our vaccine clinic visits, where we're potentially doing a very brief exam. And also for our technician visits. We are asking our technicians to make these decisions constantly, right? And they're not doing a full physical exam, and they probably have only a brief opportunity to read through that medical history. At a minimum, I do think we need to have a skim through of previous diagnoses. Does this patient have a history of adverse vaccine reactions or unwanted reactions? Does this patient have a history of autoimmune illness? And if they do, then that technician should certainly be asking a veterinarian for more specific input. As we're approaching that animal and that owner, if it's an intact female, do not forget to ask, is there any chance that she could be pregnant, right? So many of our patients are spayed and neutered. We forget about it, but don't forget to ask that. And beyond that, I teach technicians to do what I call a five -second pre -vaccine exam, right? And what we're doing there is you're approaching this animal, you're in a vaccine clinic, you're wherever, there's pandemonium, right? But this patient is approaching you, say this dog is walking up to you. You're looking at them, you're assessing, are they bright? Do they have an appropriate energy level? Do they have discharge coming from their eyes or their nose that might point to them having an infectious illness? As they're approaching you, if they are friendly enough that you can safely do this, I want to lift their lip. I want to verify that their mucous membranes are pink and moist and their capillary refill time is less than two, right? I'm going to run my hands across their mandibular lymph nodes. I'm going to run my hands down their shoulders and feel their pre -scapular lymph nodes, right? Basically, I am doing a five -second screen for evidence of overall health compromise. For infectious disease and for autoimmune diseases, right? And obviously, you're not going to pick up on every possible thing in five seconds, but you're going to pick up on a lot of it. And you can do that very briefly.

Dr. Watson [00:11:52] Yeah, I agree. I, you know, I have actually diagnosed more than one lymphoma patient that has come in for like Bordetella vaccine, just by doing what you said, just by, you know, running my hands down the animal's neck. And so that's very important.

Dr. McArdle [00:12:09] And that's something that our technicians can do. Our technicians, they're not supposed, they're not allowed to diagnose and prognose and prescribe, but they can absolutely assess and they should assess.

Dr. Watson [00:12:21] Yes. And they should assess. And then if they find something abnormal, bring that to the attention of the veterinarian. Yeah, no, that's great. Well, let's talk a little bit about, just like you said, you're kind of screening for infectious disease. So, if we've got snot pouring out of our nose or eyes or something like that. But this, I mean, this happens a lot, right? Like an animal comes in and it's got a mild illness, you know, like, like otitis. I mean, technically that's an illness. Very mild. I've also had, I've had puppies, you know, present for, you know, the owner brings back them in for vaccines, but they're just, like you said, they're lethargic. They, and then they mentioned, they've had diarrhea for three days and they end up actually being parvo -positive. So, you know, are there, do you have like very specific red lines about when you'll vaccinate or, you know, how should we be thinking about that huge spectrum that we see?

Dr. McArdle [00:13:22] Hmm. I think, it really does come down to the question of how robust is that patient's immune system in that moment, right? If you're looking at them and you are really concerned that whatever's going on has them at risk for secondary infections, then that probably isn't the best time to be doing a vaccine. The other consideration is, do we know and can we predict the course of this patient's clinical signs, right? If they have a broken nail, you can predict in most cases roughly how that's going to progress. So, or otitis or periodontal disease. So should you give a vaccine to those patients, it's not really going to muddy the waters, right? If that patient has an adverse vaccine reaction, you're going to be very clear on what's going on. On the other hand, if you aren't sure where those symptoms are going to be going, you're not clear on how that patient is going to progress, then I think that would be a situation where I'm more likely to postpone vaccines because I don't know how the vaccine is, I don't know how they're going to feel tomorrow and I don't know how the vaccine is going to impact how they're going to feel tomorrow. And maybe tomorrow I'll need to be back doing more. When I used my first job as a new graduate, I was in rural Illinois, which is the land of fungal disease, systemic mycoses, and I had a very patient first employer. If she listens to this, she remembers how patient she was with me. And I had a dog come in with a nail bed infection and it was pretty localized. And I remember saying to her, I feel like it's okay to vaccinate this dog because it's just a nail bed infection, right? And she said, I just think you should wait. And I did. And darned if that dog didn't come back in two days later with full -blown blastomycosis.

Dr. Watson [00:15:31] Oh my gosh.

Dr. McArdle [00:15:32] so I was very grateful in that situation that I waited. But in other regions of the country where we don't have that particular disease, I would be less concerned about vaccinating that dog.

Dr. Watson [00:15:46] You have in the article, we're going to move on from infectious disease a little bit and talk just briefly. Unfortunately, a lot of these conversations are going to be really brief because we have so much to pack into this episode today, but we're going to talk just a little bit about autoimmune diseases, their severity, as well as any known links to vaccinations, which I just found so incredibly interesting. So there's a table in the article that summarizes this information. And really it does appear that the only immune mediated disease that we have a very clear connection to vaccination is immune-mediated polyradiculoneuritis. So, you know, that causes the flaccid paralysis. It's similar to like Guillain-Barre in people, right?

Dr. McArdle [00:16:34] Yeah. I don't know that it's the only one, but it's the one that I included in that table.

Dr. Watson [00:16:39] The one you included in the table. So, but even though there's no clear, you know, connection that we're aware of, there definitely are consensus statements recommending against vaccines in animals with other, you know, really immune diseases that we see a little, fairly frequently, things like IMHA, ITP. So just, I was curious, just your thoughts on, you know, where these, you know, how should we be looking at these consensus statements?

Dr. McArdle [00:17:13] Yeah. The challenge with autoimmune disease is that we want to lump them all together. And the truth is that every one of these diseases is really distinct. And so we have to think about the disease individually, and we have to think about the patient individually. The other challenge is that in veterinary medicine, our data sizes tend to be very small. And so it is really hard to pin down a link, right? To be able to say, we are confident that this disease was triggered by this vaccine is really hard. So if we think about IMHA, for example, right? Let's say that I see 12 cases of IMHA in a year, and let's say that my average patient is vaccinated once a year, right? Just by coincidence, one in 12 cases that I see is going to have been vaccinated within the last month. And I mean, goodness, if that was my dog, right? I would want to be more cautious about that situation. But when we want to draw our big population level conclusions, it's a lot harder. And so with IMHA, and this is in the consensus statements, with IMHA, there is a suspected link in some cases with vaccines, our actual data trying to prove it statistically is mixed. With ITP, we really don't have any significant data at all to connect, officially connect ITP to vaccines in animals. However, ITP, thrombocytopenia, is tightly linked with vaccines in humans. We know this. We know that people will rarely get immune-mediated platelet loss following certain vaccines. And so I think we have to take it more seriously. The flip side of that for ITP specifically is that people, humans love to get thrombocytopenia associated with all sorts of viral infections. And viral triggered thrombocytopenia is not something that we see nearly as typically in animals. So I don't know how perfectly we can species relate that. But it comes down to the fact that we have reason to suspect, right? We have data in other species, we have a theoretical mechanism by which these things could be connected. And these are tremendously life-threatening diseases. And so it's different than a dog who has a very localized, or cat who has some other localized sort of immune-mediated issue. If we're talking about something life-threatening, I think we have to be extra cautious.

Dr. Watson [00:20:12] Right. Exactly.

Dr. McArdle [00:20:13] But that doesn't mean never vaccinate. It just means be more cautious about it and really think about how to moderate that plan.

Dr. Watson [00:20:24] Let's talk about cats. I know you have a passion for cats.

Dr. McArdle [00:20:28] I love cats!

Dr. Watson [00:20:29] I know, i know. So, cats with FIV and FELV and FIP, which I understand, I mean, right now talking about cats with FIP is a little bit difficult because, you know, certainly with the advent of medications like remdesivir and GS11..., I hope we find something else to call that medication soon, because I can't remember all the numbers. So we actually have cats, you know, recovering from FIP, which is a first in certainly in my career. And I know there's going to be questions about what do we do with these cats in the future and vaccinate them. There are, you know, these ones, it doesn't seem like there really are very, very many consensus statements, if any. And so just like in broad terms, what are the potential benefits as well as you know, those theoretical risks like you talked about, when we're looking at, you know, cats with some of these potentially life-threatening diseases?

Dr. McArdle [00:21:34] Yeah. So first of all, we do have guideline statements for Feline Leukemia virus and for FIV, which is the AFP retroviral guidelines. And they do give pretty clear recommendations on this for those cats. There is some speculation out there that for cats with FIV, potentially the immunostimulation of vaccines might hasten the progression of disease. There's also concern that FIV might interfere with the cat's ability to respond to the vaccines and the data on that one is kind of mixed. But for the moment, our best evidence-based guideline is that if a cat tests positive for Feline Leukemia or FIV, but is otherwise healthy, they should be vaccinated based on our general vaccine guidelines for healthy cats, as well as individual risk assessment. For cats who have progressive disease, for cats who have other evidence of immunocompromise, then we need to treat them differently. For FIP, I wish we could be having this conversation in another three to five years. We don't have the data. We don't have the data. We don't know. None of these cats have been alive after treatment long enough. Very, very few of these cats have been alive after treatment long enough to see any sort of long term progression. The concern with those cats is that the stress of vaccination could trigger relapse of FIP. I don't know. Ask me again in a few years. Anecdotally, it has happened. There are people who say I have had this happen. There are also people who say I didn't vaccinate this cat and then it died of panleukopenia, which is absolutely heartbreaking. And so I don't think that we can broadly say that we shouldn't vaccinate them. Some veterinarians out there are choosing to vaccinate while they're on treatment. Some are waiting three months after they're done. Some are waiting 12 months after they're done. I really think it comes down to that individual risk assessment as far as what sort of vaccines have they had before. We can do titers for panleukopenia. That's an option. But I'm not at the point of saying don't vaccinate them at all because I would have a really hard time having that conversation with a client after they cured their cat of FIP. And then to have panleukopenia happen, I would be pretty heartbroken by that.

Dr. Watson [00:24:15] Looking at medications, okay, so we use a lot of medications in our patients that modulate the immune system. Okay, so steroids, oclacitinib, cyclosporine, some chemotherapeutic drugs. If we have a patient that's on these medications, how can that affect the body's ability to respond to vaccines? And when should we, just like you kind of said, consider maybe delaying or just adjusting our vaccine schedule when we're on these medications?

Dr. McArdle [00:24:47] If you're giving a drug that alters the function of the immune system, and if you have the option to get vaccines done before that drug or after that drug, please do that, right? I think that's always going to be best practice. If you don't have that option, then it really varies by the drug, the specific drug. For oclacitinib, for example, the manufacturer of Apoquel has done research on this, and there is pretty good manufacturer data indicating that it's okay to vaccinate while using that medication at labeled dosages. For Atopica, on the other hand, the Atopica bottle label actually says to avoid modified live vaccines during treatment with that medication. Again, risk benefit, but I think if it's possible to follow the label, that's preferable. Chemotherapy is really variable in its impact on the immune system, and you do really have to take that case by case and day by day. If that patient has a neutrophil count of 300, that is probably not the ideal time to be administering vaccines. I think we have bigger priorities in that moment, but there are other periods of time during chemotherapy where their immune system may be more robust. And in humans, they don't straight up avoid all vaccines during chemo either. It's very situation specific. For steroid medications, prednisone, etc., it really depends on the dose and the length of the treatment. Short courses are fine. Physiologic doses are fine. Those are not going to interfere with vaccines. Immunosuppressive courses are immunosuppressive, and so obviously it's going to suppress the immune system and how it interacts with vaccines. The anti-inflammatory courses are the challenging ones. The data on that is a little bit mixed. I think in most of those cases, the immune system is going to respond appropriately, but we should be aware that there is a small chance that it won't.

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Dr. Watson [00:27:25] So I want to talk about a little bit about timing of vaccines, because this is one that I see, you know, I practice in a couple different clinics and this is one that I see different protocols in different places and people have a lot of different opinions about whether or not it's okay to give vaccines at the same time as something like anesthesia or giving vaccines when you have to give antibiotics. And now too, especially with several of these, you know, monoclonal antibody medications, is it okay to give vaccines at the same time as them? So specifically with antibiotics, the one that I always see questions about is how might antibiotics affect the efficacy of something like a intranasal or an intraoral Bordetella vaccine?

Dr. McArdle [00:28:13] Totally affects the efficacy of your intranasal and Bordetella vaccine. For most of our vaccines, antibiotics are not a concern, but our mucosal Bordetella vaccines are live Bordetella bacteria. And so if we are administering antibiotics together with a live bacteria, then we are going to kill that live bacteria. This is not so much a concern. This is not a concern with our killed parenteral Bordetella vaccines, but specifically for the mucosal. I think the biggest place that I see this come up, having worked in the Northeast in Lymeland, is there's a lot of different approaches to blue dots, right? But there is a school of thought out there where certain blue dots that come up during routine visits are prescribed a course of doxycycline. And I will leave the debate on that protocol to other people. But doxycycline is a really good antibiotic to kill Bordetella. So be aware of that if you have a patient coming in for a routine visit. And also I think dogs with skin infections, that comes up a lot where we feel like we need to be using antibiotics for this pyoderma, but they're also due for a vaccine. And the pyoderma might not contraindicate the vaccine, but the antibiotics might interfere with it.

Dr. Watson [00:29:37] And then how do you feel about giving vaccines on the same day as an anesthetic procedure?

Dr. McArdle [00:29:41] It's fine. There is data, particularly looking at feral cats. With TNR cats, there is no opportunity to do it on a separate day. And the data in TNR cats has showed that vaccines given at the same time are very effective. If at all possible, we want vaccines to be administered at least two weeks before patients are coming into the clinic environment, because we want to protect them from things like disease caught from other animals in the clinic. If it's not possible to do that, my second choice is once that patient is in recovery. And I time this in my mind when we're ready to take out the IV catheter. If they're awake enough that you feel like you feel safe having the IV out, then they're awake enough to give that vaccine. And the reason for that is that I want to be able to distinguish between, forbid that that patient had an allergic reaction to the vaccine, I want to distinguish that from an anesthetic reaction. My technicians with cats don't love it when I ask them to do that, because often my cats in recovery are still a little dysphoric when they're getting their IV out. And safety is a factor there too. And so sometimes it just is what it is. If it's not practical to do it that way, for whatever reason, do it at induction, do it at recovery, do it when you need to do it.

Dr. Watson [00:31:12] Well, let's talk a little bit about those vaccine reactions. Just like everything I feel like we've talked about all morning today, this is a huge range, right? You have vaccine reactions that are like a little soreness or develop a localized bumper reaction all the way up to, you know, just like you said, God forbid those anaphylactic reactions, you know, respiratory arrest. And so first off, if we have one that's had a mild reaction in the past, so I'm talking, you know, some facial swelling, no real respiratory, you know, issues, just just swelling and uncomfortable. What are the latest recommendations regarding premedication for those pets when they have vaccines in the future, specifically with antihistamines and glucocorticoids? Because I've seen some newer information that I found interesting.

Dr. McArdle [00:32:03] Yeah, the first thing I want you to do if you have a patient with a history of a vaccine reaction, is I want you to think in your mind, well, first, I want you to find out what the reaction actually was, right? If your pop up on your computer says vaccine reaction and nothing else, that's not enough information. And we need to delve into that. We need to know what happened? When did it happen? Which vaccine did it happen with? But the first question I want you to ask yourself as you're reviewing this is, was this a physiologic reaction? Or was this a pathologic reaction? Right? Some of our vaccine reactions are the body's immune system doing normal immune system things, right? If I get a flu shot, my arm hurts all day, and I get a big red swollen area. And my pharmacist tells me that's normal, right? And I'm not as prepared to tolerate those things in animals. I think that we have a dedication to their quality of life. We have a commitment that we've made, and I think we should stand up to that. And so if they do get a sore leg or a little fever or they're feeling tired for more than 24 hours, you know, I think that we do need to address those things and pre-empt it in the future if it's a recurrent issue. Those patients, I am going to be thinking about premedicating either with an NSAID, if they were a patient who just got really sore in the past, or an anti-inflammatory dose of a steroid, if it seemed more like an inflammatory sort of malaise. On the other hand, some of our other reactions, facial edema, you mentioned, hives, even vomiting, those are signs of a type one hypersensitivity, histamine-mediated reaction. And so for patients who have had a history of histamine mediated reactions, those are the ones who want antihistamines. And don't forget, if this is a patient who's had GI histamine signs, don't forget about famotidine or H2-receptor blockers. And so those patients really do want an antihistamine. The role of steroids in those patients is a little muddy right now. I don't know that we know for sure. I don't know of any data that's saying if we premed with an antihistamine plus or minus a steroid, will that affect the risk of a vaccine reaction happening? There is some data in patients who are being treated for anaphylaxis showing that the steroid medication doesn't actually make as much of a difference as we used to think it did. I still tend to give steroids to those patients, I confess. I'm still there, but I'm not saying I'm going to be there forever. I think there's some questions to be answered. And if the patient really has a contraindication for a steroid, if they're taking an NSAID consistently, then just do an antihistamine.

Dr. Watson [00:35:12] That makes total sense. What types of vaccines, so we talked about those, you know, pain, swelling, a little bit of edema or hives or even some GI signs, some mild GI signs, but what types of vaccine reactions really warrant stepping back and probably exempting animals from vaccines in the future? And does it matter if you switch vaccines? Like if it's a different vaccine, so they had a reaction with their rabies, but are we going to give any other vaccine in the future?

Dr. McArdle [00:35:44] Yeah. If you have the option of switching vaccines for any patient with a history of vaccine reactions, you should always do it, right? Pick a different brand. You know, if they reacted to one, pick a different brand next time. As far as vaccine exemptions, obviously there are legal and jurisdictional issues that you have to be aware of in your region. Rabiesaware.org is a fantastic website that gives state-by-state information as far as current guidelines on rabies vaccines, including rules regarding exemptions. My answer to your question of when will I give an exemption is if the reaction was anything life -threatening, right? If you did CPR after his last rabies vaccine, right? He literally died last time. I mean, let's be realistic. We're doing vaccines to try to prevent illness in the future. And if he died the last time you did it, then that's worse than anything that we might be trying to prevent. But beyond that, to any of our patients who have had systemic signs of anaphylaxis, if they have had collapse, shock, respiratory distress, remembering cats, shock can present as respiratory signs. I'm going to really avoid vaccines in those patients. For whatever reason, most of our cases of these localized hypersensitivity reactions, facial edema, et cetera, they can progress to systemic signs, but they typically don't. They typically don't. They typically are never going to have a worse reaction in the future. But if you look back to the time when that reaction was happening, if there was any point in your mind where you thought, is he going to live or not? Even like a little bit of a thought. I want you to really consider not doing that again.

Dr. Watson [00:37:43] Mm -hmm. Yeah. No, that's a very good point. So.

Dr. McArdle [00:37:47] And reiterating, these problems are extraordinarily rare. Right. Extraordinarily rare. I have been in practice for 17 years. I don't think I have ever done CPR on a patient after a vaccine. I worked with one technician who had it happen to her own pet when I wasn't there. And he did great after surviving death.

Dr. Watson [00:38:11] It's a very good point. I've been in practice 21 years, and I can remember one. I can remember one that we had to intubate because he stopped breathing. But that's it in 21 years. And it is something that I stress to clients as well is that these things are very, very, very rare, but I just want them to know what to look for and when they need to turn around and come right back to me.

Dr. McArdle [00:38:37] Right. We prepare for these things because in our lifetime, most of us as veterinarians, we'll have to make certain decisions related to this, not because the problems are common.

Dr. Watson [00:38:49] Right. Exactly. Splitting vaccines, another thing that is certainly a lot of clinicians do. I've seen recommendations, especially for smaller dogs. So splitting the vaccines may reduce the risk of reactions. This is something like the when you split them up, how long do you wait between giving vaccines? Because this is another thing that I thought I knew the answer to. And I have seen some information recently that maybe we don't need to wait quite as long between vaccines as I had thought. I always wait a minimum of two weeks between vaccines, even if it's a different vaccine.

Dr. McArdle [00:39:30] Yeah. So I'm going to go with you and say 14 days. That's our current running guideline. However, that the mechanism between that vaccine interference is pretty subtle. And immunologists will argue about this. And it does somewhat depend on which vaccine came first, which vaccine came second. What's the mechanism by which the first and the second vaccine work? You know, is this one going to interfere temporarily cause diminishments in certain elements of the cellular immune system response that maybe is needed for the next vaccine? It's actually a very complicated combination of things. And so the short answer is 14 days. The longer answer is that it's complicated, but if you have a reason you really need to give that vaccine closer together, give the vaccine closer together. Right? I mean, I don't think we should make it a routine. Routinely we should shoot for 14 days, but if there's something really pressing, just give the vaccine.

Dr. Watson [00:40:39] You already touched earlier on pregnant animals, making sure if you have that intact female come in and this happened to me, this literal situation happened to me a month ago and I just froze. I went into vaccinate had the vaccines in my hand, you know, and I went in and the, the, the client was like, Oh, by the way, she was at the boarding facility last week. And they called me and said that they, she was out in the play yard and she tied with another dog. And I was like, oh yeah. And I, so I excused myself from the room because I, I couldn't remember. I'm like, what do I do? You know, it doesn't, does it matter if it was, if it was just, you know, recently if it's in, you know, the first couple of weeks of pregnancy is if later in pregnancy. So if we have an animal, like you said, that, that was potentially pregnant or known to be pregnant, which vaccines do we need to avoid?

Dr. McArdle [00:41:45] So first off, I want to comment on something you said there, which is that you excused yourself from the room. And I know when I was a new graduate and I'm certain that there are new graduates listening to this, this was something I was terrified to do. Right. And it is fine. If you have these questions, if a weird situation comes up, just excuse yourself from the room because this is something that guidelines change on and you want to look up and verify that you're giving them the current best advice. And that's totally okay to do. I think at any of our state, any stage of our career, right. If we are vaccinating during pregnancy, the first thing we need to be aware of is that it is probably always going to be off label, right? Our vaccine manufacturers are not keen on us administering vaccines during pregnancy. Because there are risks that go with that. In particular, the risks come with our modified live vaccines and the concern that that attenuated altered live virus could have a negative impact on that developing fetus. In theory, our killed vaccine should not be a concern. If at all possible, I want our dogs to be vaccinated before they get pregnant because we need them to develop those strong maternal antibodies because we need them to pass those on to their babies. Vitally important, but if you are stuck in a situation where you really have to give the vaccine, sometimes you just have to really give them, just have to give the vaccine. Yes, there are risks. In cats, we have a risk of cerebellar hypoplasia associated with our modified live RCP vaccines. If it's possible to do a killed vaccine instead of a modified live for those pregnant cats, that would be preferable. I think practically we see that more frequently as a concern in cats versus dogs where we do have concerns of things like endocarditis or myocarditis rather and, and other problems in puppies who have received vaccines during pregnancy. But the, the guideline in shelters right now is that if a pregnant dog comes into the shelter, we are coming into a super high risk environment and the chances of something going wrong with vaccine in the puppies are, is relatively low versus the chance of mama getting parvo is relatively high, and you just give the vaccine.

Dr. Watson [00:44:23] In your article, you do talk about a few breed specific considerations, which I was unaware of these ones, you know, so one being extra-label use of vaccines in, in hybrid species, which I don't see, you know, very routinely, like I don't think I've seen a Savannah cat or a Wolf dog. But, there was an interesting, I found this, you, you talked about this association between vaccination and hypertrophic osteodystrophy in Weimaraners. And I thought that was really interesting. Could you just, just quickly kind of like go over that link for our audience? If people were unaware of it as I was.

Dr. Watson [00:45:02] Yeah. So the reason I wanted to mention some of these breed concerns is that we have so many clients who come in with questions like this, right? I just got a purebred, labra-shepherd-Frenchie-doo, and I'm sure, you know, doc that labra-shepherd-Frenchie-doos have to have different vaccines than every other breed.

Dr. Watson [00:45:22] Cannot have lepto.

Dr. McArdle [00:45:23] They cannot have lepto. They cannot have, you know, this given on the same day as that, when the, when the sun is aligned with the moon, and many of those concerns are not scientifically founded, but they're not all unfounded. There are a few concerns out there that even if they aren't big worries, and even if we kind of know that those patients will be fine, no matter what we do, which most of those patients will still be fine, no matter what we do. The, our clients are not crazy for asking the questions. So regarding the HOD vaccination link, there is no HOD vaccination link. There is an HOD vaccination theory. And the place where this theory comes from is that we don't understand perfectly the pathophysiology of hypertrophic osteodystrophy in dogs. And in particular in Weimaraners, where it is a more complex disease. We do know that in early studies of HOD, there were cases where distemper virus was isolated from the bones of these dogs. And so one of the early theories was that HOD was caused by infection with distemper, with canine distemper. And that theory evolved into, could it be that this is vaccine virus, modified live vaccine, distemper virus that we're finding causing problems in the bones of these dogs? The, the natural play out of that was a feeling that if we were to select recombinant distemper vaccines, instead of modified live distemper vaccines, that we could prevent puppies from getting HOD. The other factor with this, is that HOD is a disease that affects primarily puppies of a certain age. And so the vast majority of puppies diagnosed with HOD have had a vaccine administered within the last three weeks. But is that correlation or causation? We don't really know. So this question came up and for a while, it was very standard thinking that recombinant distemper vaccines were safer for Weimaraner puppies than modified live vaccines because Weimaraner puppies have risk for breed predisposed HOD. There was a study that came out, actually not recently anymore, it was in 2013, where they collected up a whole bunch of cases of dogs who had been diagnosed with HOD. They found 53 dogs, small studies in the veterinary world, right? But for this disease, that was a lot of dogs. And of those 53 puppies, 21 of the puppies had only received recombinant distemper vaccines. So I don't know if there even is a link, but it is a theory. It's a theory that's still out there. It's something your clients are going to ask you about. And unlike certain other breeds, it is a scientifically founded question. If you wanted to stick with recombinant vaccines, I think that's not crazy. If you wanted to do one of these modified protocols where you're doing titering at points in time to verify that they're protected, I think that's not crazy. But there is no evidence at this time that avoiding vaccines prevents HOD.

Dr. Watson [00:49:01] So kind of a good reminder that yes, lots of times these questions come up. Again, if you don't know the answer, it's okay to say, let me go look at the latest research on that. Let me step out of the room. But actually it kind of comes up to my last question for you, kind of sets it up perfectly. Thank you. Which is if we have clients that are particularly concerned about an adverse event in their pet, I mean, we certainly, we all advocating for giving vaccines, that vaccines are the vast majority of vaccines are safe and beneficial in the vast majority of our patients. So do you have any like resources or talking points for clinicians when we're having these discussions with what seems to be a little bit more vaccine hesitant client population these days?

Dr. McArdle [00:50:01] Yeah, we're having these conversations a lot, aren't we? I think that we are all feeling kind of bombarded with this anti-vax, anti-science movement. And I think that's really stressful for us, but I want to remind all of the practitioners, all of the technicians, all of the receptionists, everyone who's working with clients with these questions, that the vast majority of our pet owning clients who are coming to see us are very pro-science, right? And if they're asking questions, it's not typically because they're anti-vax. It's because they're attempting to be advocates for their patients, their pet's wellbeing, right? We have all learned this in the health system, that it's important to advocate for ourselves, for our loved ones, for our children, for our pets. We have to be advocates and that's what they are doing. And they're asking these questions and they're having these hesitations because of that. And so I think if we can recognize that, it's easier for us to feel that these really are our, I've heard them called A clients, right? These are our A clients who are asking this because they want to be there for their pet and we do too. And so if you have someone who's expressing these concerns, the first thing I want you to do is ask them why, where is this coming from? What have they heard? What have they read? Have they had an experience with this pet or with a different pet where an unwanted reaction occurred? And sometimes they had something really scary happen. Maybe this client who is hesitant today had a cat who died from an injection site or a vaccine-associated sarcoma in the past. Maybe they had a pet who had a puffy face. If something like that happened or whatever they've read or heard, we do need to pause and address those concerns and be patient. Often this pops up right as we're ready to leave the exam room, which is very annoying timing, but breathe it in, shift your body language, lean on the wall, sit back down, whatever you have to do that says, I am here to have this conversation with you and recognize these concerns. And a lot of the times, as long as you don't treat their concerns as silly and you don't treat their concerns as insignificant and you take the time, which might be two minutes or it might be five minutes, it should not be 20 minutes, right? But if you take that two to five minutes and address those concerns, I know that messes up your schedule a little bit when you do it over and over and over, but remind yourself that that builds trust with that client, which will shorten future conversations about other things because they know that you're here in this conversation with them. You know, they take, they know you take their concerns seriously. When you advise them on things in the future, those conversations will be much faster. And so in a workflow standpoint, it will pay off in the long run. I think you'll find a lot more vaccine compliance with that. As far as resources go, AAHA has a document online. It's called the top 10 facts that owners should know about AAHA's canine vaccine guidelines. I think that's a really good document. But for my clients who have really high level concerns, and there are some of them, right? And with cat owners, they all come to cat clinics, I feel like. For clients who have high level concerns, send them an email link to the AAHA vaccine guideline, the AAFP vaccine guidelines, the WSAVA vaccine guidelines. Some people want to read every one of those hundred pages and more power to them.

Dr. Watson [00:53:48] It's okay to send them home with just a little homework.

Dr. McArdle [00:53:51] It is, yes. Especially if they ask for it.

Dr. Watson [00:53:54] Yep, exactly. Oh, goodness. This was a fabulous conversation. And I know we've kept you a little while, but I would like to keep you just a few more minutes if it's okay. This brings us to the end of our episode, which is our rapid fire part of the podcast. This is some of our... Yeah. Oh, I'm glad you're excited. This is my favorite part of the podcast. This is just some would you rather questions that I just rapidly shoot at you and you answer right off the top of your head. Do you want to play?

Dr. McArdle [00:54:25] Yeah.

Dr. Watson [00:54:26] Okay. All right. Would you rather spay an obese, mature dog, or would you rather perform full mouth extractions on a cat?

Dr. McArdle [00:54:35] Oh, I'm going to get in trouble because I'm a cat veterinarian. I'd rather spay the dog.

Dr. Watson [00:54:40] I'd rather spay the dog too. I'm not a dental person. All right. If you had to work a relief shift, a busy relief shift at a crazy hospital, would you rather it be a major holiday or Friday the 13th?

Dr. McArdle [00:54:56] Major holiday.

Dr. Watson [00:54:57] Major holiday. We're staying away from those crazy Friday the 13th days.

Dr. McArdle [00:55:02] Yeah.

Dr. Watson [00:55:03] Okay. Would you rather have your best staff member say, gee, it's really quiet today, or, oh my gosh, that vein is huge?

Dr. McArdle [00:55:15] Oh, I yelled at our new hire technician for this on her first day. We had a new technician and my other technicians were having trouble getting an IV into a patient and they'd already, of course, hit several veins unsuccessfully. Of course, they call me over. As a doctor, the only time you put in an IV catheter is when everything else has fallen apart.

Dr. Watson [00:55:37] They're all blown, everything else.

Dr. McArdle [00:55:39] They're all staring at me in a group and I'm looking down at the patient. I'm looking at the vein and our brand new technician, she's two hours into her first shift. She goes, that vein looks so, and I go, NOOOO. So, now she tells everyone about how I yelled at her on her first day. I don't remember the other option, but I want that.

Dr. Watson [00:56:13] That's what you want. Okay. All right. Would you rather find out that the litter of kittens that you were just snuggling all over had ringworm or have a client that wants to show you their rash?

Dr. McArdle [00:56:30] Ew. Kittens with ringworm. No, I don't want to see their rash and it's always somewhere that I really want to see it. I.

Dr. Watson [00:56:35] Don't want to see anything on a person. Nothing.

Dr. McArdle [00:56:37] Yeah. It's never like a rash on their forehead.

Dr. Watson [00:56:41] Okay. Last question. Last question. If you were dressing a giraffe for a formal occasion, would you put the bow tie at the top of the giraffe's neck or down at the bottom?

Dr. McArdle [00:56:54] Top, because I think it would make him look more dapper.

Dr. Watson [00:56:57] More distinguished. All right. I love it. That was it. Did you have fun?

Dr. McArdle [00:57:01] I did!

Dr. Watson [00:57:04] Excellent. Well, this was fantastic information. I'm sure that our audience is going to love this and play it over and over just to go back and catch all of these, these wonderful pearls. So thank you for joining us. And you know, maybe one day you said you'd have the answer to those FIP questions. So you got to come back on.

Dr. McArdle [00:57:23] Yeah. Let's revisit this in a few more years. This was fantastic. Thank you so much for having me today.

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