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Clinician's Forum: Expert Views from a Roundtable on Lyme Disease

Clinician's Forum: Expert Views from a Roundtable on Lyme Disease

Infectious Disease


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Clinician's Forum: Expert Views from a Roundtable on Lyme Disease
Brought to you by Elanco


  • Brian Herrin, DVM, PhD, DACVM (Parasitology), Assistant Professor, Parasitology Kansas State University
  • George Moore, DVM, MS, PhD, DACVIM (SAIM), ACVPM (Epi), Director of Clinical Trials and Professor of Epidemiology Purdue University
  • Radford Davis, DVM, MPH, DACVPM, Associate Professor, Veterinary Microbiology & Preventive Medicine Iowa State University
  • Jessica Pritchard, VMD, MS, DACVIM (SAIM), Clinical Assistant Professor University of Wisconsin–Madison


  • Casey Locklear, DVM, Elanco


  • Lyme disease and leptospirosis are on the rise and are both considered to be nationally notifiable diseases.
  • Everyday activities could be putting dogs at risk for both diseases.
  • Lyme disease is best prevented through daily tick checks, avoiding tick habitats, using year-round acaricides with a label claim against Ixodes spp, and vaccination, which CAPC supports.
  • Doxycycline is an effective treatment for both diseases; however, Lyme can “hide” in joints, making protection against Lyme disease particularly important.
  • Leptospirosis vaccination should be considered core in many areas.
  • Where Lyme is endemic or emerging, dogs should be screened for exposure to B burgdorferi, Lyme vaccination should be considered core, and year-round tick control should be recommended.

Lyme Disease: Who’s at Risk, Best Preventive Measures, & Future Spread of Disease

With a thorough understanding of Lyme disease, where it is in the United States today, why it is spreading, and our best measures available in protection against disease, veterinary professionals can not only empower themselves and their teams to educate more owners on this dangerous disease and which pets are at risk but also help protect more patients.

Dr. Locklear: Why is Lyme disease spreading, and where is it in the United States today?

Dr. Herrin: Like a lot of things, the spread is challenging to pin down to 1 thing because we have Ixodes on the east coast, but this is a much narrower geographic area for Lyme disease. What’s interesting to me is the difference in behavior, feeding, and activity of the more northern and southern populations of Ixodes where they could potentially be a risk. They can all carry Borrelia but don’t seem to maintain that cycle normally and don’t seem to quest in a similar way. So, the expansion that we are seeing—at least in the US—southward isn’t because of southern ticks picking up the bacteria for the first time; it’s really a movement of the northern populations south and across the Ohio, Indiana, and Illinois area. A lot of it is because of reforestation efforts and because white-tailed deer populations are still massive, then, if you add in climate change making everything warmer so the ticks are heading north to Canada, that’s a cause as well. But this also likely creates these weird microclimates in which ticks may be able to survive in certain areas, higher elevations, or something like that where they hadn’t been able to before. We saw that movement down the Appalachian Trail, which was a little bit weird, and now up into northern North Carolina. It seems the 2 populations got bottlenecked, separated at 1 point, and now are reconnecting. So, there is the potential that the northern clade could continue to move south. That’s the tick side.

Dr. Davis: There is a big grab-bag of things that I think are influencing the spread of ticks, the spread of the disease, as well as the prevalence of the pathogen within the tick. I think part of it is climate change, so as things have warmed up, it’s definitely spread. You’ve got the forest fragmentation and climate change, and different studies have shown different things regarding forest fragmentation. On a big scale, that seems to correlate, but on a smaller scale, maybe not so much. Different things come in to play, including the microclimates of a forest, the historical aspects of what humans have done to the environment—not only the clearing of forests but also hunting, what predators or competing hosts have been rid of or altered. Then we add in things like human behavior; I’m not sure we can easily say that climate change is wholly responsible for the transmission of Lyme disease or the increased number of cases or the spread of ticks. It’s definitely complicated.

Clinician's Brief

Dr. Herrin: When we are looking at dogs and human cases as our reporting metric, or what we are trying to build our risk maps for, the interaction in an area between the ticks and us or our dogs is what’s important. So, if you have a gigantic forest and you never go into it, that risk is super low, but if you slice it up with a bunch of trails and send everyone on a hike, you increase that risk. So, you have to account for how many times we are interacting with those ticks, whether it be by suburban sprawl or reforestation efforts.

Dr. Moore: The challenge, too, is in broad-scale infectious disease surveillance in many diseases that are zoonotic or have the risk for similar transmission by being vector-borne. Human medicine (often courtesy of the CDC) is often helpful in giving us not so much animal data but human data in a timely fashion that helps us. And certainly, that was getting our attention several years ago; regrettably, my experience with checking with the CDC website on Lyme disease is they are a little bit behind. I think the last one I saw was a 2018 map of human data. So I do want to recognize with both appreciation and accolades to the veterinary parasitology groups, particularly CAPC, that have worked to try to pull together information with canine data using information from some of the commercial laboratories to help us stay a little more in tune and aware of dogs that are showing evidence of exposure, perhaps infection with Lyme disease with Borrelia burgdorferi. The other aspect is that we may not be thinking nationally as much as what’s happening in our locale. And there is still the importance of remembering the life cycle that, quite probably, if we are using a screening test, means a test this spring really is reflecting exposure of quite possibly last year or last fall.

Dr. Pritchard: I think that is one of the interesting things about the blue dots, those maps that we used to get. Similar to Dr. Moore, I miss 2018. We haven’t had any of those beautiful maps since then; they were great to watch the spread and see where those dots were showing up and how dense they were in the areas where we live and practice. And there has been the interesting change in the reporting to the CDC, too; physicians can now report suspected or confirmed cases of Lyme in humans. I suspect, provided that we ever get those blue dot maps back, we might see a change in the distribution and density of those dots. So having the CAPC data and other published data of where the disease is in dogs, knowing that dogs serve as sentinels for human disease, will be super helpful for us as veterinarians and from a public health aspect.

Dr. Moore: And even though the maps are specific for Borrelia burgdorferi, I think from an infectious disease point of view about what might happen clinically, not only from the fact that these ticks can carry copathogens (so is there something other than Borrelia that I’m worried about?) but also due to new and evolving information of other Borrelia species. Some of them are potentially causing relapsing fever-type issues in people, and we’re not sure the degree to which those will occur in dogs. Sometimes it is simpler to fixate on Borrelia burgdorferi, but when we talk about tick control and other aspects, we really have a whole lot to consider under this tick-borne disease umbrella.

Dr. Davis: The other thing is, when most people are diagnosed, they are counted as a case by where they live. They should be potentially counted as where they were exposed or where they contracted it, but that can be kind of hard to figure out.

Dr. Herrin: And the CAPC maps also have no ability to account for travel.

Dr. Locklear: As we become more responsible with products applied to crops and suburbanizing areas, some host species become more abundant, but this also allows those animals to encroach upon where we live. Any commentary on that interaction?

Dr. Davis: So this is the issue of planetary health, how humans alter the environment or we insert ourselves into new places of the world and expose ourselves to different animals, animal species, and microbes that probably have been there for quite a long time or may be new. So, as we build cities, as we expand, and especially as people like to live on the periphery of cities to get away from the urbanization but have a little bit of wilderness in their backyard, that certainly puts them at risk for contracting arthropod-borne diseases, be it Lyme disease, be it plague in the southwest. And that’s something that I think that we need to recognize—even the issue of something as simple as outdoor cats. Letting cats go outdoors, that impacts the local biodiversity, the rabbits, the birds. That all kind of has a domino effect. We are altering our environment, so we are exposing ourselves to new things all the time.

Dr. Herrin: I think reforestation and supporting that network in which all organisms benefit from biodiversity have a major role in changing how prevalent diseases are. But really, I think it makes it easier just to step back and say we’re not going to really be able to control ticks on the wildlife scale. There are lots of cool efforts that have been tried, but they are just so cost- and labor-intensive to try to control things in the wildlife. Wildlife is what it is; we can only control what’s in front of us and that potentially is your pet. We can’t broadly spray all of the forest, right? We have to just control things on your animal.

As we expand, we are putting ourselves at risk for arthropod-borne diseases, and we need to recognize that.—Dr. Davis

Dr. Moore: It is interesting how wildlife in its microevolution has adapted to the presence of us, the different things that we do. And then we do certain things that could be viewed as progressive or a little more reflexive as we start bringing in backyard poultry and more and more people want to have something that would be more reminiscent of what our grandparents did and how that also attracts rodents and wildlife. So, I think there are many aspects in which we will be continuing to see these diseases putting pressure on us and, interestingly, as we get more knowledgeable, even more new and evolving diseases.

Dr. Locklear: What dogs are at risk for Lyme disease today?

Dr. Pritchard: I would say, in areas where we know there’s Lyme disease, dogs that go outside are at risk and need to be protected. I think there is a tendency on the part of many owners to say, “Well, I never see ticks or fleas in my yard.” So, in turn, if we called them wildlife- or bird-associated diseases, more owners might say, “Well, I do see birds in my backyard, even in the city,” or, “Yes, occasionally I see raccoons at my trash can.” So, I think really, especially in endemic areas, dogs that spend any amount of time outside should be protected from Lyme and other tick-borne diseases.

Dr. Locklear: From a parasitologist perspective, why do we pervasively hear pet owners say, “I just don’t see ticks” when we know we are doing screening tests and getting positive results? Why is the pet owner not seeing them?

Dr. Herrin: It’s challenging. They’re small; they hide in places. You know, are we checking the dog’s armpits, inguinal area, perianal area? And the answer is no. So, what is a tick check? I know what it is when we describe it in an SOP for ourselves after doing studies, but how would we describe how to do a good tick check to our clients?

Dr. Moore: When you see the large, engorged tick, that obviously gets your attention. I think sometimes it’s helpful to be able to show a chart or information that actually lets the client see the size of larval and nymphal stages and discuss if you can really see these in your red dog, your black dog, and so on.

Dr. Pritchard: I think talking with owners, too, about where to check, going head to toe, and looking at all of those areas is so important. So, in between the toes and those areas that you may not think of because they’re not areas that you pet very often—like the axillary region; none of us are really petting our dogs in their axillae that commonly. Many dogs don’t like their feet touched, but you have to look between their toes. And I think that the discussion of how complicated a really good, thorough tick check can be is an important part of preventing these diseases. And that really brings forth the importance of why we have these other methods of protection, too—why we don’t just rely on a tick check. I have a Labrador with a very thick, dense coat; there are areas of her coat where I can barely get down to her skin with my fingers, especially now coming out of winter and into spring. So, I think physically showing owners what we are looking for and where we are looking can be helpful.

Dr. Davis: And if you’re talking about the spread into new areas where people may not be as aware of Lyme disease or they don’t think it’s a big deal, they are not going to be checking as readily. They’re probably not going to be using flea and tick prevention readily.

Dr. Pritchard: I think a lot of people in endemic regions would say, yes, they’re checking their dog, or even in newly emerging regions, but how many owners are truly checking their dog at the end of every day when they go out in a suburban backyard where there are white-tailed deer, white-footed mice, and things like that? I think a lot of us tick check our dogs after that big, exciting hike out in the wilderness but not necessarily after the day-to-day activities where they could still be at risk for meeting up with some Ixodes.

Dr. Herrin: The “it’s in every county except for my county” is a huge issue. That’s one of the pieces I like about the CAPC maps at the county level; if you are seeing it there, that’s timely and local. You encourage the practice to move that gross tick jar from the back of the clinic to the front and say, “We see ticks on dogs. We have them here.” We just had our first cat die of a fatal tick-borne disease, so get your prevention now—every year. Low risk is not no risk.

Dr. Locklear: Why would tick control alone not be enough to prevent Lyme disease? What are some of the pros and cons of tick control and its practical application?

Dr. Pritchard: I think any veterinarian would agree that compliance is always an issue and is not always 100%. There’s a study that I really love that was a survey of dog owners in Ithaca, New York, at a dog park. It’s not a perfect study, but I think it’s interesting because of what it tells us about what our clients know about why we are doing the things we do for their pets. So, owners at this dog park were surveyed and asked if they use flea and tick control on their dogs, and only 55% said yes. I’d love to know what percent purchase flea and tick control from their veterinarians or told their veterinarians they were using it, where they might believe they’ll be judged if they had said no versus what percent gave an answer in what they perceived to be a judgment-free zone to some random researchers in the dog park on a Saturday afternoon. But only 25% could mean any sort of flea-borne disease, and only 40% in Ithaca could mean 1 tick-borne disease, so that kind of drives home the point that our owners are trying to do a good job, and they are trying to do what we recommend to them, but maybe they don’t always understand the why. So, I think that, although we have excellent products now to prevent tick attachment on our pets, we don’t always have that complete compliance with our owners that we would hope for.

Get your prevention now—every year. Low risk is not no risk.—Dr. Herrin

Dr. Davis: Why do you think that is? Is it because people are unaware that they should be using it, let’s say, year-round? Or because they don’t want to spend the money to use it the entire time? Or they just forget?

Dr. Herrin: Yeah, it has to be a combination of all. Money is always a big one. I think the veterinarians who are most successful in compliance are probably those that are educating and rounding that whole package out of why we are testing for these pathogens, why we are using these preventives, and providing some of that background information on what they should be using. I think the older generations of pet owners are more likely just to do what the veterinarian said because they said it, but the younger generations are really asking for information to drive their decisions. So, providing some baseline can help: what is the risk and what risk are you willing to accept?

Dr. Moore: I think we as veterinarians— and, quite possibly, to some degree, pet owners—recognize the value of preventing tick-borne diseases. So, I do think that there is an understanding of the value of regular screening for these particular diseases. I think a challenge for practitioners is understanding why we’re running these tests because we don’t always know what to do with the result in the sense of vaccinating or not. And I try to remind them that a positive result for Lyme disease— whether a blue dot or some other signal— tells you first and foremost that tick control has failed. But it’s become a measure of compliance; it doesn’t matter what you sold, it doesn’t matter what they said they did. It means the control has failed, so that should evoke conversations, whether that’s by the veterinary nurse, the veterinarian in the exam room, the front desk, or otherwise. But the idea of understanding that these lapses—even well-intended as we may have been— do put our pet at risk, and I’m not saying that’s money wasted that was spent with us, but we didn’t do a good job of preventing in that regard. So, we may not have time to dissect all of the at-home situations, but certainly we can talk about it and say, “Okay, good. How often are you going to give this?”

Dr. Herrin: I think, specifically for Lyme and Ixodes, the other challenge is that ticks are out at what I think people don’t think is “tick time.”

Dr. Davis: That goes back to our earlier discussion about why Lyme is spreading. Why is Ixodes spreading? I think it comes back to human behavior, which also influences whether we are using tick preventives correctly for as long as necessary.

Dr. Locklear: What dogs should be vaccinated for Lyme disease?

Dr. Pritchard: I would say it’s the same dogs that we identified earlier that are at risk for exposure because, even though tick control and prevention is the first line of defense and a great line of defense, it’s not 100% for various owner compliance reasons. This is that extra layer of protection that we can give to these pets that isn’t dependent on owner compliance that we can assure happens when they’re in the room with us for their exam.

Dr. Locklear: Specifically, what lifestyles do those dogs typically have, or where are those dogs residing that should be targeted for vaccination?

Dr. Pritchard: Dogs that go outside in areas where we know Ixodes ticks and Lyme disease are present— because it’s not just dogs that are out in the country or that go hunting; it’s dogs that go outside where there are mice, rabbits, and white-tailed deer that are at risk for bumping into an Ixodes tick, and that’s often in our backyards in addition to the other places, fun places, that we take our dogs to, like parks and hiking, camping, and hunting. And we know it can be at our own homes as well.

Dr. Moore: I think there is also tension in balancing between quantifying expressing disease risk to an individual versus balancing with an acceptability of vaccination as the preventive measure. If we can quantify the risk and the owner is agreeable to a vaccine, tertiary will be the question of how do I fit that into my protocols. There is discernable risk to dogs, as cited in controlled studies in which the industry or universities took dogs that were not vaccinated and were known to be infected and followed them, up to necropsy and histologic examination of joints. In all studies, untreated infected dogs showed histologic evidence of increased inflammatory cells around joints, so the degree to which we quantify and attribute that to Lyme disease is challenging. Another recent study also documented that dogs that were positive for either Borrelia or Ehrlichia showed an increased risk for later developing chronic kidney disease. The pure magnitude of that was not explicitly quantified, but there was an increase in odds ratios and nearly a 50% increase in risk. So, the potential for a longer-term sequela that would require further medication—maybe even long-term or nonstop medication such as NSAIDs—prompted a number of us to consider that vaccination should be considered in all dogs in these endemic areas and become part of standard protocol. You should be discussing it, particularly, as we said, when we are showing evidence that compliance with tick control is not satisfactory. We’ve got to quantify risk, and I think the other part with communication will be the concern from owners.

Dr. Locklear: Where are we with Lyme disease vaccination strategies, safety, and how would you tie that into your typical protocol?

Dr. Moore: So, the information and concerns expressed by clients sometimes is helpful. In an interesting article, a physician at the Mayo Clinic was looking into behavioral aspects of people and why people refuse vaccines, particularly new vaccines. And it went everywhere from perceived risk of disease to associated historical things about vaccines to people who just don’t want to be the first in line. So, trying to understand the basis for their concerns or fears might be worth just a minute or 2 in conversation in case they’ve had a bad experience with another vaccine in a pet or if this is something they read on social media. We can certainly tell them that we have been able to follow documentation on vaccine safety and so on and that has, in the last several decades, allowed us to produce better and better vaccines. We want this to be a good experience. Protection is much more important than trying to treat reactions. Some work we presented at the ACVIM forum showed that, where we were doing proteomics to evaluate different protein signatures, our Lyme vaccines had some of the minimalist protein signatures across the board, with just a very few number of excipient proteins being recognized. Even lepto is only slightly above that, so it is showing the ability and concern by the industry to produce high-quality products.

Dr. Locklear: Regarding some of the shared risk factors between Lyme disease and leptospirosis, what are some prevention methods we can take to help increase awareness for both of those in our dogs that are at risk because of those commonalities?

Dr. Pritchard: In terms of the commonalities of the wildlife vectors of these diseases, we have to look for lepto in areas where we maybe previously didn’t think dogs were at risk, like in cities. There are plenty of rats in cities and places where dogs could be exposed. Similar to Lyme, lepto also is a noncore vaccine, although the ACVIM consensus statement does note that there are regions of the country where it should be considered core. There are animals that live in our backyards or in the courtyard of our high-rise apartment complex that we know spread these diseases, like rats or raccoons; dogs that go outside in these endemic areas need to be protected from both spirochetes. I think, in terms of how you convey that to owners, it might be as simple as having photos of the animals—you know, a raccoon, a rat, a mouse, a white-tailed deer, a songbird. “These are the animals that help spread the vectors or diseases in our area. Do you see these in your day-to-day life? If you do, then your pet could potentially be at risk for these diseases, and we have great ways to protect them.” In the summer, people think about icky bugs and things flying around, but no one wants to think that their pet is going to be at risk for what those things can expose them to. So, it’s getting them on board with understanding what the risks are for their pet and how common they may be.

Veterinarians can be a voice for sound science—the historical success of vaccines, their continued success, and why they are important in animal health and in public health.—Dr. Davis

Dr. Davis: This also speaks to the greater issue of vaccines as well. Veterinarians can be a voice for sound science—the historical success of vaccines, the continued success of vaccines, why vaccines are important in animal health and in public health. I think we play a role in explaining that it’s a benefit to their health and trying to alleviate any of the fears that you can identify in conversations with them.

Dr. Moore: With leptospirosis, our main action is dependent on vaccination. In contrast, with Lyme disease, we can discuss the 2-pronged approach of the value of tick control. So, vaccines are still important with Lyme disease as a backup to our other ectoparasite control, so vaccines become important for both the prevention of the potentially fatal and/or chronic conditions that could ensue from either infection. But sadly, how the owner and dog usually live becomes the dynamic in the owner’s mind—like if they’re usually in the apartment or indoors, they don’t need to be vaccinated. But if they go outside at all, they’re really at risk for leptospirosis as well as these other diseases that we’ve mentioned. And I was talking with Dr. Leah Cohn at Missouri about how we have these lepto cases in the ICU, and they are not big-breed dogs; they are little ones. So, the challenge is that small-breed dogs, terrier breeds in particular, may be at greater risk than other types of dogs. We already know and have ascertained it is rare to diagnose lepto in our clinic in a properly vaccinated dog, but we’re seeing a transition in the dogs and vaccination. There wasn’t awareness of increased environmental risk with leptospirosis. The numbers of the large-breed hunting type, sporting-type dogs that were going out in the woods were being vaccinated, but that left our backyard dogs, our smaller dogs, unprotected by our practitioners.

Dr. Locklear: Why do we still need tick control in a dog that is vaccinated?

Dr. Moore: We want vaccinations for protection against Borrelia burgdorferi but also to expand that spectrum to catch the small amount not protected against Lyme disease, in which case we do want to rely on a tick control product.

Dr. Pritchard: And each dog is an individual, too. We say the duration of immunity is X amount of months, knowing in some animals it is slightly longer or slightly shorter, but having that 12 months’ worth of tick control helps cover the difference in variation amongst those individuals too, in terms of how long their individual duration of immunity lasts.

Dr. Herrin: For me, I often get asked about overuse of doxycycline or just treating when I see a blue dot on the test and whether I do it. But one of the first things I say is, “The best way to be a good antibiotic steward is to prevent on the front end,” so you’re seeing so few ticks due to good tick control and vaccines where appropriate that you’re not seeing a blue dot at all, so you don’t have so many dilemmas. So, maybe when you see that one a year and you wonder whether to do more diagnostics or just give doxycycline, you’re already decreasing your kind of antibiotic footprint there in leaning very heavy in the preventive side of that equation.

The best way to be a good antibiotic steward is to prevent on the front end.—Dr. Herrin

Dr. Locklear: What are some ideal characteristics in a Lyme vaccine?

Dr. Moore: There is a little bit of a challenge scientifically to know what the most appropriate way is to prevent Lyme disease or infection. The originally designed vaccines, and even now those under consideration for people, are focused on an OspA molecule. These are grounded on a scientific basis that, within the tick, there has not been any conversion of OspA to OspC. That turns out to be not so guaranteed, either perhaps later in warmer summertime or if the tick for other reasons has had some changes molecularly with all of this going on. And then there is also a concern expressed in the consensus statement as to whether an OspAonly product has as long a documented duration of immunity, so products that focused on both OspA and OspC were generally viewed more favorably by the consensus group. At this time, the main considerations probably among the vaccines are whether they deal only with OspA or whether they have an OspA and OspC component.

Dr. Pritchard: I would agree with Dr. Moore in terms of wanting that dual protection with OspC and OspA, knowing that OspA will be your primary driver working in the tick and then having that OspC protection for those instances where maybe some of those Borrelia have all of their ducks in a row for whatever reason— external temperature or they were just on another animal and then hopped onto your dog and are already expressing OspC. In terms of looking at the vaccines that we have, looking for that dual protection is what I most commonly recommend.

Dr. Locklear: Should we be testing all dogs every year for Lyme disease? If so, what test should we be using for that screening?

Dr. Pritchard: I think yearly screening provides a nice opportunity to have those conversations about those diseases without necessarily fear-mongering but explaining that we’re screening for these diseases each year for a number of different reasons. It’s essentially a barometer of how well that flea and tick control product was used if that pet is positive but asymptomatic for one of those diseases that we are screening for. I think having those yearly screening tests builds in time to have those conversations.

Dr. Herrin: I think this is really challenging because I obviously do want yearly testing because the surveillance is interesting; it’s helpful for the practice to know what’s in their area, but I can also understand clinics that may not want to, in that they don’t feel it’s a value to their clients. When you get that antibody positive, that’s your chance to have that conversation about tick prevention and whether your strategy is working and potentially work down the diagnostic pathway, but it just becomes difficult to interpret when that’s positive for multiple years and you don’t act differently every year. I do like the antibody test, but the issue with them is you can see so many positives with no clinical disease that you can just start to dissociate the 2 where that blue dot doesn’t mean anything. I love the test and in-clinic assays—trying to help people interpret them, figure out what the workflow should be from that positive, and how to use that information where it is actually of value to the client and not just a service to overall public health.

Dr. Pritchard: Having a workflow is important. Agreeing as a practice and having a consistent approach amongst doctors is so important; when we see that blue dot for Borrelia, we know that owner is going home with 3 prelabeled urine cups to screen for proteinuria, and we’ve got reminders in our system for them to drop off the urine for the rest of the year. Something like that where we take action. Not everything has to be the same for every patient, but in general, this is important to do.

Dr. Herrin: Something I get questioned on is when there are 2 practitioners, and one has seen a really horrible Lyme case and the other never has, so they have very different protocols where the one who has seen the terrible case is going to keep checking urine, following up, and doing these things, and the other who has never seen it says, “Yeah, it’s pretty unlikely your dog is going to get sick. You’re probably okay.” And they want to know which one of us is right in this type of a situation. 

Agreeing as a practice and having a consistent approach amongst doctors is so important.—Dr. Pritchard

Dr. Pritchard: It’s a hard place to be in, to have those differences in opinions and different experiences and how that informs the way we practice and what we recommend to our clients. It’s not an easy decision on what to do with those dogs for sure, and I think the consensus statement reflects that difficulty in decision as well. And there have been at least in the last 5 to 10 years a number of different tests that have become available, which I think has complicated things a little bit in terms of patient-side tests and what we can test for. Certainly some offer looking for different outer surface proteins expressed at different points of infection, so with OspA, they would call that vaccinal, although there are reports that say this dog has never been vaccinated. I know that I’ve had this dog as a client since a puppy and it’s showing up as vaccinated but not positive for outer surface protein C or F, which they would say is acute or chronic infection based on that test. So, it seems like they’re not perfect but still a marker of potential exposure versus other tests looking for other proteins expressed during natural infection. And we don’t know how many of those dogs will go on to develop disease. I think that’s the difficulty with this test as opposed to leptospirosis, where we have the benefit of potential PCR testing or repeat serologic tests and we can say with a little bit more definitiveness that this animal is infected and is acutely ill from this.

Dr. Davis: And I think it’s really important that, no matter what a veterinarian or a human doctor is testing for, they have a plan. If it’s negative or positive, you should have a plan for what you’re going to do with that result. From a public health perspective, when we talk about zoonotic diseases, I talk to students about testing healthy animals versus clinically ill animals for zoonotic diseases, the benefits and the pitfalls, and what doing the testing in a healthy animal means. You need to have client education up front, why you’re testing and what you can expect from the test.

Dr. Pritchard: I bring that up with our residents with another test for Borrelia all the time, the quantitative C6 test that’s available. I think a lot of the time the decision has already been made whether you are going to treat that dog with antibiotics, so does the quantitative C6 really help? And from an academic standpoint, do we have evidence that supports use for that test in this dog longterm? So, I think that’s a really good point to have a plan based on the tests that you are submitting.

Dr. Locklear: I think the question we hear first and foremost is what do we do with a blue dot in an asymptomatic dog? So, let’s start there on the blue-dot positive, asymptomatic dog. What steps does that veterinarian take next?

Dr. Moore: I think individual experience has an effect on that—or if clinicians went to different schools, how they were trained, or the concepts taught by their instructors, but the idea with treating is that you’re trying to make an attempt to eliminate infection. That’s what we would normally be trying to do with an antibiotic treatment. One of the challenges is duration of treatment; some recommend 14 days for Ehrlichia, and others recommend 28. Others are saying we have to have a minimum of 28 for Borrelia, so what is the issue? Is this time-dependent? Is it dose-dependent? Our challenge with Borrelia is compared to when we see in a person the bullseye, the erythema migrans, the idea that maybe the organism has not yet gone deep into fibrous connective tissue around joints. Then again, if the patient is not showing many clinical signs or any clinical signs, then it is very hard to say, “Well, I will use response to treatment as my guideline.” There are consequences to any of our decisions; even no decision has a consequence. And I think trying to discuss consequences with owners is important—so asking if they have a preference.

Dr. Pritchard: I usually at least recommend screening for proteinuria at a bare minimum in terms of something we can do that’s no risk to the dog, costs substantially little. Just starting with a dipstick; if it’s negative, you’re done. If it’s positive, then you move to quantification and probably a full urinalysis. Then Borrelia may or may not be the cause of that dog’s proteinuria, but you’ve still identified something in that dog that could adversely affect its life that you can take action on now. So I would say, at minimum, that I push practitioners to recommend at least screening for proteinuria.

Dr. Davis: If you have a blue-dot positive dog that doesn’t have proteinuria, do you still treat that dog?

Dr. Pritchard: I believe it’s an option in terms of the pros and cons because you could be treating that periarticular inflammation or treating before the dog gets to that point that they’ve developed that cystic or L-form Borrelia within their collagen in their joints, so there’s that potential that we just don’t know if we’re treating that or not or could we potentially be preventing glomerular disease later in the course of that dog’s lifespan? With my own dog, before she was vaccinated, she was positive in Philadelphia, and I treated her, but that was my decision based on being a vet student at the time, what I knew, and what I perceived to be the risks and benefits to her.

Dr. Davis: I would think, as a client, if I took my dog to a vet and they tested the dog and it came out positive but my dog seemed perfectly healthy, and the vet didn’t want to treat, I would say why not? It’s got a disease, right? It’s infected; you should treat. I would think this would put the practicing veterinarian in a very difficult position to explain why they bothered to run the test if they’re not going to treat.

There are consequences to any of our decisions; even no decision has a consequence.—Dr. Moore

Dr. Pritchard: I think that’s a hard spot for practitioners to be in, to essentially sell the benefit of this yearly screening test or looking for evidence of exposure to this disease but then saying now we’re not going to treat your dog for what they’ve had exposure to. I think that’s where we need that extra time to talk about what a serologic test means in terms of exposure and what the other diseases that we’re looking for on that test could mean for their pet. That’s why I think it’s hard to take a hard line of saying, “No, I will not treat any positive asymptomatic dogs,” because we just don’t have the evidence to say that we’re not preventing those other potential sequelae down the line. That being said, we don’t have the evidence to the opposite to say we need to treat all positive asymptomatic dogs. So that’s where I think you need that longer conversation with the client.

Dr. Locklear: In thinking about whether screening tests have merit, does the answer shift when we look to different geographies in the US?

Do we view our approach differently in emerging areas, the fringe areas where we’re experiencing Lyme disease? Do we need to screen more or less in those areas? Do we interpret a blue dot differently in these more emerging disease areas?

Dr. Herrin: I think the starting difference is the conversation of trying to determine if it was picked up locally. If you’re on the fringe area, you’re trying to decide who needs to be vaccinated in a risk-based scenario and all the things that come with it. If it was acquired locally, then that’s where you can put that forward in your clinic and say, “Hey, we have dogs testing positive for Lyme. This is something that we need to talk to our clients about, educate them.” So, in terms of first step, for me, do they think it’s there?

Dr. Davis: And lifestyle and travel history; I think that’s really important.

Dr. Locklear: Looking to Lyme in puppies and prevention protocols, what do you feel are best practices for Lyme disease prevention in puppies, especially when we are talking about puppies coming in for the new puppy exam?

Dr. Herrin: There is evidence that owners who start their pets on preventive programs very early tend to spend more consistently throughout the dog’s life than those that start later. So, we know that setting up those preventive programs early in life, setting the expectation of what a normal visit looks like, and things like that really set the stage for compliance and trust building so that they will take your recommendations seriously.

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Dr. Locklear: There are products available that are labeled for puppies as young as 8 weeks of age. When would we add vaccination to that preventive strategy?

Dr. Moore: There are a couple of the dynamics to consider. You’re leaning heavily on tick control, regarding exposure and preventing transmission of disease, because, in some of our testing, we’re not going to have a positive test indicating that exposure or risk until some months away. Yet, if I’m in an endemic area and this is a vaccination that I want to consider, due to this dog’s location and lifestyle, I would try to include it fairly early on and get it into a regular pattern. Looking at a full protocol, if we are going to complete our rabies initial series, parvovirus, distemper, those viral products that I will then be moving into a 3-year booster, I’d think, okay, now Lyme disease is something that will require annual revaccination, as would leptospirosis and, potentially, some of the respiratory components such as Bordetella. So, we need to communicate that we will have to give these viral ones every 3 years as an adult but are going to see the patient annually for screening for infectious diseases as well as protecting for selected infectious diseases such as leptospirosis, Lyme disease, etc. Then, we want to make sure that we have 2 leptospirosis vaccines that are given appropriately, but these are in the later part of the puppy series. And Lyme can be administered in general at that same time; indeed, there are even products available that can combine those. So I think most of our vaccination protocols become a strategy—of not only protecting the animal but thinking through helping the client to be dependable and easy for them to comply with our schedule that we will work with.

Dr. Pritchard: I think not one protocol necessarily fits all pet parents, and working with them to find something that is suitable for their lifestyle and their dog is important. And so is a lot of that education up front, not only about tick control but also about these diseases we see in our area that we’re going to be talking about. Every year, when I see you with your pet, we will be talking about fleas, ticks, Lyme disease, and leptospirosis, and this will just be a regular part of our conversation. And hopefully it will never be that we’re treating your pet for these diseases because you’re well-protected and we’re starting that early.

Most of our vaccination protocols become a strategy—of not only protecting the animal but helping the client be dependable.—Dr. Moore

Dr. Locklear: Should we vaccinate a dog that has been naturally exposed?

Dr. Moore: I would say, clinically, there is a concern that such an animal might be at increased risk for Lyme nephritis if we don’t know all of the details about the inciting causes for that; that would be the concern. In general, I believe a majority of internists would feel that an appropriate course of antibiotics would help reduce the pathogenic load, the potential immunologic response, allowing that to decline. Some may feel that may be grounds for a type of quantitative test such as quantitative C6 or something else that shows there is a reduction in measured biomarkers, but the assumption is that, if that is reduced, we will have a reduced likelihood of stimulating some nephritis or immune complex disease. So, it’s very challenging because I almost want to have the tick control talk again as much as I want to have the vaccine talk again because, at some point, we are dropping the ball. I think antibiotic therapy may keep the wolf away from the door, but that’s just for Lyme nephritis potentially and any other associated clinical disease. And I think we’re still back to what is the real lifestyle of this animal? How much are they exposed, and what preventive measures are truly in place by the owner?

Dr. Pritchard: I think the other difficulty too is, if I ideally want to recommend treating that dog that has been naturally exposed before I vaccinate it, can I count on that owner to take a month of doxycycline home from this visit, then come back 2 more times for the first vaccine and the booster? And can I compromise and start the doxycycline and give the first vaccine on the same day because I don’t feel confident that this owner is going to come back an additional 2 times when they are already either late or have poor compliance with their tick prevention?

Dr. Locklear: Considering the past decades with Lyme disease, what do you think the future of Lyme disease is in the United States?

Dr. Herrin: More ticks in more places.

Dr. Davis: We definitely see it spreading east and north, both the tick and the disease. And the same trends in Europe as well. I think that, as it spreads and people become more aware, we’re going to see increased testing of dogs and people, increased awareness among physicians, and increased exposures.

Dr. Pritchard: I agree that we will continue to see spread. I hope we’ll also see more awareness of preventive strategies or adoption of prevention measures—like a simple tick check postwalk, better utilization of the many different options that we have for tick prevention, and vaccination becoming more routine in places where the disease is endemic and emerging. I’m also hopeful for more research on other Borrelia species in dogs and humans.

Most of our vaccination protocols become a strategy—of not only protecting the animal but helping the client be dependable.—Dr. Moore

Dr. Davis: And there are probably more organisms out there that we haven’t discovered in ticks. Probably more Rickettsia, more Borrelia. The CDC put out a great report looking at tick-borne diseases, and from 2004 to 2017, the number of tick-borne diseases tripled in that time period.

Dr. Moore: I think most of us, particularly if associated with a university, recognize the impact on our lives and the reduction in meetings, continuing education, professional meetings. And I think that has had a bit of a detriment within the profession in the sense of what we get used to seeing. So, the people in endemic areas are used to seeing Lyme, maybe they get more set in their ways, but to help other people learn, we do use CE conferences to go in and learn about new things or things that may be coming our way. So, I do hope that research, both on the human and veterinary side, will continue to provide insights for this disease and other diseases that are transmitted by ectoparasites.

Dr. Pritchard: Client education and buy-in is key, and this is a disease that I think requires some conversations and monitoring for vector-borne diseases in general, treating for them, and preventing them. Those wildlife-associated diseases require conversations with owners about our preventive strategies and why we’re doing what we’re doing because a lot of it relies on them carrying those forward at home.

The less impact we can have on our planet on the biodiversity and the ecosystems, that’s sort of like a vaccine for the emergence of disease that we can essentially lessen the impact of.—Dr. Davis

Dr. Davis: From a public health perspective, too, I will just reiterate this connection of the human impact on our ecology, our ecosystems, and biodiversity; Lyme is a byproduct of that, so we need to be constantly aware of how we are impacting our environment, our impact on agriculture, deforestation, reforestation, and all that goes along with that. We talk a lot about climate change and how that’s going to impact Lyme disease, and that’s just one component. We are impacting and helping Lyme disease spread by a lot of the other things that we as humans are doing, and I think that needs to be conveyed in the big picture of things. The less impact we can have on our planet on the biodiversity and the ecosystems, that’s sort of like a vaccine for the emergence of disease that we can essentially lessen the impact of. Lyme disease, in my estimation, is probably a naturally occurring disease that has been around for a really long time, and it’s because of our lifestyles, our way of living, and many other things that we are interacting and coming in contact with that.

Dr. Herrin: The description of Lyme as a disease entity happened so late because of the almost complete extirpation of white-tailed deer and the early reports of some kind of Lyme-like disease pre-deforestation efforts when the white-tailed deer number was high, so we may have almost nearly eradicated the disease but, in keeping any deer, we were unable to. So, I think it’s here to stay. For the client, it’s every pet, every month, all year round; there are no real options because low risk is not no risk, so it’s up to our veterinarians to try to understand and describe that risk to those clients.

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