MERIAL VACCINES LYME MANAGEMENT TECHNICAL UPDATE

MERIAL VACCINES LYME MANAGEMENT TECHNICAL UPDATE

MERIAL VACCINES LYME MANAGEMENT TECHNICAL UPDATE Approaching the Topic of Canine Lyme Disease with Veterinary Clients A Discussion for Veterinarians and Veterinary Technicians Andrew K. Eschner, DVM For humans, mosquitoes are the number one arthropod vector of disease, but ticks trail immediately behind. 1 The reverse is true in veterinary medicine, both internationally and in the United States, where ticks transmit numerous bacterial (and viral) pathogens that can lead to serious illness in livestock and companion pets. 2 Ixodes scapularis (adult female) Image courtesy www.cdc.gov. In the U.S.A., the tick-borne disease known as canine Lyme disease (more aptly described as canine Lyme borreliosis) is front-and-center in the realm of companion animal health. Canine Lyme borreliosis (CLB) has gained a lot of attention because of the influx of infected ticks into previously naïve geographies and the fact that dog-owners have grown keenly aware of the consequences of infection. Lyme disease in both humans and dogs is a relatively new disease entity in the U.S.A., documented in humans in the late 1970s. Even so, it has been the focus of years of research and has received great attention in the media. There are several national advocacy groups for Lyme disease and numerous local Lyme disease support groups for humans. The facts and emotions centering around CLB can be confusing so there is need for dog owners and veterinary staff alike to better understand what is at play when the term Lyme disease is mentioned. CLB is a relative newcomer of the tick-borne diseases documented to infect dogs. In the U.S.A., CLB was first described in the literature by Lissman and others in 1984. 3 In comparison, other potentially devastating tick-borne diseases of dogs were described earlier in the USA, namely: Rocky Mountain spotted fever (1933), ehrlichiosis (late 1960s), granulocytic ehrlichia complex (now anaplasmosis, (1982).) 4,5,6 Compared to other diseases, CLB discussions often dominate a routine office visit in endemic areas. A disproportionate amount of time can be consumed discussing the prevention and management of CLB sometimes crowding out much-needed discussions pertaining to other important health management topics (e.g., dentistry, nutrition, heartworm compliance, etc.). One reason this occurs is because of the nature of the infection and the disease. The organism s insidious capacity to infect a dog after the bite of an unseen tick can be disheartening. The organism s unique ability to persist in the dog following infection despite antibiotic treatment poses emotional and intellectual challenges that demand time for explanation. Managing the infection and its corresponding disease requires knowledge of the facts married with clinical judgment. The goal of this article is to provide an overview of the ecology of the tick vector and bacterial organism that causes CLB so that the reader is better able to discuss the management and prevention of the disease with clients. Mrs. Jones Your Dog Is Lyme Positive. This is a common phrase echoed through exam rooms in veterinary hospitals located in many areas of the country. The seemingly complex maze of discussion surrounding CLB often begins with announcement to the owner of a blue-dot positive result on a popular in-clinic blood test (SNAP 4Dx Plus, IDEXX Laboratories, Inc.). The Lyme specific blue-dot portion of this four-way test detects the presence of a unique C6 antibody made by the dog in response to infection with the bacterium, Borrelia burgdorferi (Bb). 7 The detection of this unique antibody (made visible by the formation of a blue-dot) signifies that infection with Bb occurred as little as 3-4 weeks previously. Lingering antibodies can trigger a positive test for at least 12 months after infection, even in the absence of clinical signs. 7a Therefore with the Blue-dot positive result, the complex task of deciphering what it means (and what to do) has only just begun. Image of the SNAP 4Dx Plus Test. Approved for the testing of Borrelia burgdorferi, Dirofilaria immitis, Anaplasma phagocytophilum, Anaplasma platys, Ehrlichia canis and Ehrlichia ewingii. Courtesy of IDEXX Laboratories. Copyright 2015, IDEXX Laboratories, Inc. All rights reserved. Used with permission. 1

Decisions to either treat with antibiotics, watch-and-wait, Another important variable in the geographical variation of where conduct more tests, vaccinate and improve tick-control Lyme disease exists is the lack of suitable reservoir hosts (white-foot techniques come into play simultaneously. Once a dog becomes mice) and/or an abundance of lizards in the southern and even infected, the proverbial horse is out of the barn and can be western USA. Lizard serum will lyse many Borrelia species and for difficult to wrangle. Therefore, the ultimate goal should be to this reason they do not harbor Bb to any appreciable degree.9 focus all efforts on reducing or eliminating the opportunities for Subsequently, the infection rate of black-legged ticks in these areas is infection to occur in the first place. Understanding a little more lower. Ixodes pacificus, the western black-legged tick, transmits Lyme about the two organisms involved the tick and the bacterium in the western U.S.A., mainly along the more humid Pacific Coast. 8 is a component of reaching this goal. The Tick Vector Fortunately in North America, only one tick genus has been found to effectively provide safe-harbor for and efficiently transmit the bacterial agent of CLB, namely the black-legged tick (Ixodes scapularis) and the Western black-legged tick (Ixodes pacificus). As with other ticks of importance to small animal Schematic showing the relative size proportions of the various life stages of Ixodes scapularis. Courtesy www.cdc.gov veterinary medicine in the USA, Ixodes scapularis is a three-host tick which successively feeds on a different mammal during While the majority of human disease can be correlated with the peak each of its three growth phases from larva to nymph to adult. activity of nymphal ticks (mid-may to mid-july), the seasonality of These ticks are mainly forest dwellers spending most of their life transmission in dogs may be different.8,10 It is the adult either in the leaf litter where moisture is high and the risk of drying black-legged tick that prefers to feed on dogs. Adult Ixodes scapularis out is low or on leafy green vegetation measuring less than ticks feed from October through April which is a larger window of knee-high in height.8 I. scapularis is mainly found in the eastern time (almost 5 months longer) than humans experience for infection half of the USA. However, dryer and hotter microclimates within risk.10 Because nymphs can (but don t necessarily prefer to) feed on this general zone may fail to harbor as many ticks. Because the dogs, this author believes the risk of seeing an infected dog is more nymphal stage of this tick is the key stage for transmission of apt to be year-round. Disease-causing bacteria within ticks need to the Lyme bacterium to humans, the feeding behavior of this go through a reactivation phase in order to become infective to the stage of tick is believed to be one important factor in host. They need to modify themselves after having lived in the determining where human Lyme disease is prevalent. The biting mid-gut of a tick for many months (if not years) at ambient outside (and questing) habit of nymphal black-legged deer ticks tends to temperatures. To turn on the necessary genes in order to move into favor humans in the mid-atlantic states through Maine and the the dog (100 F +), most research points to a required tick feeding upper Midwest.8 In many parts of the Southeast, nymphal ticks time of at least 48 hours to maximize the potential for infection.8 are more difficult to collect (by flagging ) and are generally less Simply stated, in the case of Lyme disease or CLB, there is plenty of a nuisance to humans.8 of time to remove a tick if you know it s there. The problem is that rarely are these poppy-seed size (nymphs) or sesame-seed size (unfed adult) ticks seen in the hair coats of dogs. Schematic of the abundance of Ixodes scapularis and I. pacificus ticks in the US. Courtesy American Lyme Disease Foundation (http://www.aldf.com/usmap.shtml) Data Source: Diuk-Wasser, M.A., Gatewood, A.G., et al.,2006. Schematic of the seasonal activity of the various life stages of Ixodes scapularis. Image courtesy of TickEncounter Resource Center, URI. www.tickencounter.org 2

The white-tailed deer is believed to play an important role in the increasing abundance of black-legged ticks throughout the eastern U.S.A. 8 In a personal conversation with Sam Telford III, Department of Biomedical Sciences & Infectious Diseases at the Tufts Cumming School of Veterinary Medicine, it was described how white-tailed deer essentially serve as large feeding stations, feeding greater than 93% of all black-legged ticks in the local environment in a given season (Wilson 1990). Although almost decimated at the turn of the 20th century due to widespread deforestation and hunting, the population of white-tailed deer after WWII has increased exponentially due to many variables including re-forestation, reduced hunting, and the existence of fewer predators. The simultaneous slow migration of people from urban to forested suburban areas has placed humans in direct contact with deer and the ecosystems which support increased disease transmission. During a personal conversation with Dr. Thomas Mather at the University of Rhode Island s Tick Encounter Resource Center, it was estimated that each autumn, a single white-tailed deer will feed enough adult Ixodes scapularis ticks that will drop off to lay as many as 450,000 eggs. the flesh, digesting host proteins along the way and evading the defense system of the animal. 12 Borrelia burgdorferi at 1000X. Image courtesy of Dr. Reinhard Straubinger, U. of Munich, School of Veterinary Medicine. Lameness and arthritis are the classic manifestations of clinical CLB and have been shown to occur mainly in the region of the body that experienced the tick bite. 13 For this reason, Bb is not believed to disseminate through the blood in dogs. This is affirmed by the recently introduced veterinary laboratory PCR test panels that do not assay for Bb in blood samples. Research has shown that Bb evades host defense mechanisms by actually regulating key host proteins and by constantly changing its appearance (surface antigen expression). 12 During a personal conversation with Dr. Richard Jacobson, Professor Emeritus, Department of Population Medicine and Diagnostic Sciences, Cornell University, College of Veterinary Medicine, he likened the interplay of spirochete and host as a game of cat and mouse. Persistence White-tailed deer. Source: Wikipedia, the free encyclopedia. Not copyrighted. The Bacterium of Canine Lyme Borreliosis Borrelia burgdorferi (Bb) is a corkscrew-shaped spirochete bacterium that causes CLB and all forms of Lyme disease in people and dogs in the U.S.A. This spirochete has been well studied and its entire genome has been sequenced. A fair portion of its genetic information is used to manufacture well over 130 outer surface proteins that allow it to migrate (disseminate) and live (persist) in both a tick and a warm-blooded mammal at various points in its life. 11 Upon injection by a tick that has fed for almost two days on a host, the spirochete corkscrews its way through Few infectious bacterial agents have been documented to persist as long in dogs after infection as Borrelia burgdorferi. This is an important reason to aggressively strive to prevent infection from the outset. The spirochete s unique ability to regulate and evade the host s immune system and set up shop in the body results from its unique ability to bind to collagen fibers, proteoglycans, and chondroitin universal components of most mammalian tissues. 14 Research in dogs has shown that after transmission by the bite of infected ticks, Borrelia burgdorferi multiply slowly and their numbers peak at 60 days reaching numbers up to 1.5 million bacteria in a single small punch-biopsy skin sample. 15 Infected dogs are literally teaming with Borrelia spirochetes. It is truly amazing that more clinical illness is not recognized. 3

With bacteria numbers high and deep within tissues, even aggressive 30-day treatments of antibiotics from a variety of drug classes can fail to clear dogs of infection. It has been shown that some dogs can remain persistently PCR-positive for Borrelia burgdorferi up to 500 days after antibiotic treatment. 15 The story is not all bad, however. In this same study, a good many dogs were eventually cleared of their infection and the number of bacteria in the dogs that were not cleared fell precipitously by a factor of 1,000-fold. 15 The bad in all this is that we have evidence that CLB can persist in dogs for perhaps years despite our best efforts. The effects of infection in any given dog can range from no effect (no clinical signs) to devastating consequences. Once the infected dog has recognized key proteins on the Borrelia and responded with antibodies, the ability to detect the footprint of infection begins. Diagnosing Canine Lyme Borreliosis It is important to distinguish between infection and the clinical condition of disease. Infection, disease or both? This is an aspect of diagnosing CLB that can be confusing to both the veterinary health care provider and dog owner. Not all infected dogs show signs of disease; anywhere between 5-65% of dogs have been reported to exhibit observable clinical signs of illness after infection with Borrelia burgdorferi. 16,17 Direct methods (culture and PCR) of finding B. burgdorferi in tissues are the Gold Standard of detection, but are conducted rarely in the practice setting due to cost, time, equipment and the invasive nature of sampling (biopsy). These methods are not without their drawbacks (sampling errors, contamination) but are very good when conducted in quality laboratories where attention to the detail is well monitored and processes and machinery are validated through rigorous testing methods. Indirect methods (of antibody detection) come in two general forms: (1) send-out services to diagnostic laboratories contained within companies or universities (western blot, quantitative C6, Lyme Multiplex, AccuPlex and (2) patient-side, point-of-care test kits (i.e., SNAP ) that many veterinary hospitals utilize on a daily basis. These methods are somewhat easier, less costly and less invasive requiring only a serum or blood sample. While very accurate for infection under most circumstances, point-ofcare test kits do not provide information about vaccine antibody or chronicity of infection whereas send-out confirmatory tests (above) may. Consult the package insert for additional information on any test you choose to use. Rely on Lyme antibody tests from quality manufacturers or universities who have validated their results against known positive and negative samples determined by culture and/or PCR. When detecting antibodies to Borrelia burgdorferi, the geographic region in which the dog lives should be considered. A positive Lyme-antibody test from a dog living in a region where black-legged ticks are rarely observed (or have low rates of infection) should raise some initial suspicion. The predictive value of a positive test in a low prevalence area may not reflect the sensitivity/specificity rating on the package insert of the test. A confirmatory test should be conducted on that sample. Confirmatory tests may include your choice of a western blot, Lyme Quant C6 (IDEXX Laboratories) or Lyme Mulitplex assay at Cornell. In 2012, 95% of the reported human infections occurred in 13 states: PA, NJ, NY, MA, CT, WI, MD, MN, NH, DE, ME, VA, VT. 18 Clinical Signs of CLB Clinical signs of Lyme borreliosis in dogs living in the U.S.A. include joint/limb swelling due to inflamed synovial membranes, lameness due to arthritis, myalgia, anorexia and fever. Facial palsy and cardiac symptoms, although documented frequently in humans, are not hallmarks of CLB. A rapidly fatal nephropathy syndrome, putatively associated with Lyme-specific immune-complex deposition into the kidneys, is recognized and is not uncommon in regions endemic for Lyme disease. 19,20 Unlike a viral infection (parvovirus, distemper) that can take just 5-7 days to manifest into profound clinical features of disease, the incubation period from infection with B. burgdorferi to clinical disease in dogs ranges from 50 to 169 days. 15 It is truly a stealth pathogen that can take many weeks to months to develop into a problem following the bite of an infected tick(s). Signs of CLB tend to occur within the same time frame of two important occurrences in the body when total spirochete numbers (up to 1.5 million as discussed above) peak in tissues and when antibody levels are at their highest. 4

CLB in the U.S.A. Dogs positive for Borrelia burgdorferi have shown up in virtually every state in the U.S.A. based on serological testing results assembled by researchers.26 While perhaps true, the incidence of clinical CLB in these states is far from clear or well reported. In humans, the Centers for Disease Control in Atlanta, GA, publishes a map of the USA showing where human Lyme disease has been reported.27 Superimposing the CDC map onto the map showing Fibrinopurulent synovial fluid filled with neutrophlis. Images used with permission of Reinhard Straubinger (U. Munich). where Ixodes scapularis (black-legged ticks) are found reveals the correlation as to where Lyme disease exists with any frequency. An animal health technician once dramatically compared these spirochetes to being like maggots in an open wound and this allowed her to better appreciate (on a macro level) the immense load of bacteria with which infected dogs contend. Why don t all dogs exhibit profound clinical disease? Research in human Lyme disease has revealed that a person s genetic make-up and possibly the unique virulence of Bb in a particular geography may influence who becomes ill and who does not.21 This may apply to dogs as well. Do Labrador, Golden Retrievers and Bernese Mountain dogs have a peculiar genetic make-up that may predispose them to a fatal form of Lyme nephropathy? Some believe so and advanced genomic studies in the next few decades may shed more light on the immunopathology of Lyme disease. Dogs experiencing the classic signs of synovitis/ arthritis due to CLB respond well to doxycycline (10 mg/kg SID) or amoxicillin (20 mg/kg BID).22 The time period of treatment Reported Cases of Lyme Disease United States, 2012. One dot is placed randomly within the county of residence for each confirmed case. Though Lyme disease cases have been reported in nearly every state, cases are reported based on the county of residence, not necessarily the county of infection. http://www.cdc.gov/lyme/resources/reportedcasesoflymedisease_2012.pdf. has traditionally been 30 days, but whether 30 days provides significantly better therapeutic efficacy than a 14- or 21-day course has not been studied. Doxycycline has been in short supply in A very similar map utilizing data collected on 982,336 dogs the U.S.A. since 2012 and costs have skyrocketed. Minocycline tested for B. burgdorferi antibodies from 2,573 animal hospitals has been proposed as a viable alternative for dogs at an oral dose across the U.S.A. was published in 2009 by Bowman, Little of 10 mg/kg twice daily. This author is unaware of any veterinary and others in the journal Veterinary Parasitology. 28 As with the research to confirm the efficacy of minocycline in CLB, but Borrelia CDC map, the veterinary map localized the prevalence of Lyme burgdorferi has been found to be susceptible to minocycline, antibodies to be in states where black-legged ticks are in in general. greatest abundance. In the Bowman et al paper, almost 12% 23 of the canine blood samples from the Northeast U.S.A. were Cefovecin (Convenia, Zoetis Animal Health), a novel, extended- positive for B. burgdorferi antibodies. In contrast, only 1.0% spectrum semisynthetic cephalosporin, has been reported to be of the samples collected from the Southeast were positive efficacious against Bb in dogs at the dose of 8 mg/kg at two, (mainly Virginia). There were focal areas that appeared hyper- 14-day dosing intervals. In humans, a single dose of 200 mg of endemic; the most notable areas occurring in the coastal doxycycline has been shown to be effective in preventing Lyme Northeast and upper Midwest. Putnam County, NY, recorded disease if given within 72 hours of a tick bite, but this regimen positive results as high as 44.1%, 43.0% in has not been studied in dogs. Washburn County, WI, and 60.9% in Todd County, MN.28 24 25 5

Vigilance Preventing CLB in Dogs What if you do not live in a state that is known to be endemic for CLB? The key word is vigilance. At least along the eastern U.S. corridor, dogs and their owners routinely travel in and out of areas thick with Ixodes scapularis ticks containing Borrelia burgdorferi. Awareness and knowledge of testing, treatment and prevention procedures are still important for veterinary staff members, regardless of where you live. In recent years, ticks have begun to ignore the geographic boundaries that humans have ascribed to them. This author grew up in central New York State and practiced and lived in eastern NY until 27 years of age without seeing a single tick on a dog or a person. It is now commonplace to see ticks and tick-borne diseases every day in these areas. The same is true about other geographies heading southward into the mid-atlantic states, Virginia and the Carolinas. As deer continue to expand in numbers so too do the ticks that ride and feed on them, namely Ixodes scapularis (heading southward) and the Lonestar tick, Amyblyomma americanum (heading northward). The useful acronym for remembering the need for a comprehensive approach to preventing CLB is V.E.T., for Vaccinate Educate Tick Control. 31 The only tick-borne disease of dogs in the U.S.A. that has a vaccine available for prevention is CLB. Vaccination, in combination with reputable educational resources on how to manage, avoid and remove ticks, both on the pet and in the yard, is important. Likewise, compliant, year-round use of quality tick control products administered (or applied) to dogs will go far in helping to reduce infection with Borrelia burgdorferi from feeding ticks. Three canine Lyme disease vaccines. Recombinant OspA (left). Photo courtesy of Merial archives. While they have nothing to do with CLB, Gulf coast ticks are an example of another tick species that is expanding its geography in the USA. The expansion of Black-legged, Lonestar and Gulf Coast ticks into previously uncharted territories will likely expand the spectrum of various tick-borne diseases of dogs and cats. Copyright photo courtesy of Dr. James Freeman, (Merial). Different counties within states may experience dramatically different microclimates and support ecologic conditions appropriate for some ticks, but not others. Birds have been documented to transport ticks into various locations and song birds have been documented to be competent reservoirs for Borrelia burgdorferi. 29,30 The darkening tide of expanding tick geographies is sure to alter the disease prevalence maps you see today. Again, the key word is vigilance. Lyme disease vaccines, regardless of type, play an essential role in helping to prevent Bb transmission from tick to dog. Vaccines take advantage of a vulnerable outer surface protein (OspA) that the bacteria manufactures during its residence within the tick and prior to being transmitted. Antibodies generated against OspA via vaccination work by immobilizing and inactivating Bb within the tick prior to it hiding (down-regulating) its OspA protein. Two types of CLB (Lyme disease) vaccines exist for dogs: first generation whole cell bacterin preparations containing multiple Borrelia antigens (including OspA) with adjuvant and a second generation recombinant subunit formulation containing purified OspA without adjuvant. Both vaccine types protect based on their ability to generate antibodies to OspA in the vaccine recipient. There is currently no evidence that naturally infected dogs benefit in terms of Borrelia clearance when re-vaccinated with either of the two vaccine types. However, because natural infection antibodies do not confer protection against subsequent (future) infection when bitten by additional infected ticks, there is some justification to consider revaccination of asymptomatic, infected dogs with a Lyme disease vaccine. The hallmark of the recombinant OspA vaccine is that it allows for strategic delivery of the key protective antigen (OspA) against CLB to both uninfected dogs and asymptomatic positive dogs. The benefits of strategic delivery of OspA antigen are threefold: focused immunity, less 6

interference/confusion with the interpretation of serological tests which rely on infection markers like OspC, and avoidance of the creation of antigen-antibody complexes to nonessential spirochetal surface antigens. Although OspC and other spirochetal outer-membrane proteins found within whole-cell bacterins have been aggressively marketed as providing enhanced protection from infection with Borrelia burgdorferi, the actual benefit of their inclusion has not been clearly shown in peer-reviewed publications. 32,33 To the contrary, the utility of OspC as a vaccine candidate has heretofore been limited by its tremendous structural variability and the wide range of distinct OspC serotypes found in North America. 34,35,36 The inclusion of multiple, pro-inflammatory Borrelia proteins within whole-cell bacterins has been considered to contribute to overall vaccine reactivity. 37,38,39 Due to this potential, whole-cell bacterins against Lyme disease have rarely been considered serious candidates for development in humans. To the contrary, a novel multi-ospa vaccine is under development in Europe for human use and extraneous antigens, including OspC, are not components. 40,41 Although several whole-cell bacterins against CLB have been marketed in the U.S.A. since 1992, none have shown the proposed benefit of multiple antigen inclusion in side-to-side, controlled, blinded and randomized challenge or field studies. To claim that the addition of a new vaccine component (variable) improves efficacy, three test groups are required within a trial: one containing dogs receiving only the new or additional antigen(s), one group receiving both the new variable and OspA, and finally one group receiving simply OspA alone. This has not been completed. When vaccinating, it is recommended by this author that pups in endemic areas be immunized at the earliest age listed on the package insert and then annually. To date, there is no evidence that maternal antibodies to OspA interfere with the ability of a pup to begin responding to vaccination when administered at the minimum age indicated on package inserts. Evidence does exist that maternal-derived OspA antibody in the serum of pups wanes prior to 3 weeks of age. 42 In endemic areas, a delay in immunization may increase the likelihood for infection especially when a new puppy owner is still getting used to purchasing and applying tick-control products. Regardless of vaccine type used, some Lyme disease experts recommend the addition of a single booster vaccine administered 4-6 months after the initial series of two followed by the annual vaccine given 6 months later. 43,44 Tick-control (acaracide) products in the U.S.A. include those made from members of the phenylpryazole, synthetic pyrethroid, macrocylic lactone, foramidines and isoxazoline families of compounds, none of which are labeled to prevent tick-transmitted pathogens in dogs. The Companion Animal Parasite Council (www.capcvet.org) recommends that tick products be used throughout the year as many tick species are active throughout the year or can become active when temperatures rise briefly during the winter months. 45 How Should I Approach CLB in My Practice? This brings us full circle as to why so much time is spent discussing CLB. There is no single correct way to view and manage the infection. One thing is clear: make sure that everyone in the practice is on the same page when it comes to the hospital approach to the diagnosis and management of CLB. If there is wide disagreement in the management, testing and treatment philosophy, your clients will surely become confused by the inconsistency. First, build a foundation of what you believe to be true about CLB based on the best available evidence and discussion. The following questions may assist your hospital team in assessing what tactics you take to prevent CLB in your practice. Do you have the tick vector (Ixodes scapularis) in your area? Do people acquire Lyme disease in the counties that your animal hospital serves? Do you believe or know (through testing) that dogs get infected with the agent of CLB, namely Borrelia burgdorferi? Do you believe/agree that dogs can become ill after infection with Borrelia burgdorferi? Even when vaccinated according to schedule, the first 16 weeks in a pup s life is a vulnerable time period for B. burgdorferi transmission because vaccine-induced immunity is maximal 3 weeks following the booster vaccine. Schematic created by Dr. Andy Eschner (Merial). Do you believe that the spectrum of clinical illness (arthritis, painful joints, lameness, fever, possible fatal Lyme nephropathy) warrant a comprehensive prevention strategy in your hospital? 7

If you have answered yes to more than a few of the above questions, your hospital should consider incorporating a Lyme surveillance screening test into your yearly heartworm assessment. Additionally, all dogs exhibiting lameness, fever, joint swelling, or muscle soreness should be tested for the presence of antibodies to B. burgdorferi (and Anaplasma phagocytophlia). See previous discussion above on testing. Likewise, implementation of a CLB vaccination protocol should be considered. If you did not answer yes to any of the questions above, CLB is likely not viewed by your hospital veterinary staff as a priority disease to be prevented at this time. Or perhaps it is understood to be a disease worth preventing, but you feel the low risk in your area does not currently warrant the time and client expense. A Note of Caution: CLB should not be the only driver in the determination of whether aggressive tick control measures should be implemented in any geography. The prevalence of other, often more severe, tick-borne diseases of dogs in the U.S.A. (RMSF, Ehrlichia species, Anaplasmosis) warrant comprehensive, year-round tick control measures. Please consult the web-links which follow this article for the presence of other tick-borne diseases in your area. Second, once you determine that preventing CLB is a priority, implement the V.E.T. principle for a multidimensional approach to prevention. 31 No single prevention strategy is complete for all dogs so a simultaneous layering of the methods (Vaccination-Education-Tick control) is important. A dog that departs the veterinary hospital having received a 1-year Lyme disease vaccine but only a few doses of their favorite tick control product is a dog that could have its tick-control (the 'T') coverage improved. Third, decide on your approach to the blue-dot, but attempt to keep it consistent throughout the practice. There are basically three approaches that have been recognized in veterinary hospitals in Lyme endemic geographies. Each approach has its merits and advocates. This author estimates that >90% of veterinarians in CLB endemic areas utilize Approaches 1 & 2. The three general approaches highlighted here support the fact that no single way is necessarily more correct. Treating CLB often involves a trio of important considerations including: (1) the veterinary view point, (2) clinical and laboratory findings, & (3) owner emotion/viewpoint. On occasion, a veterinarian s medical philosophy may be to not treat an asymptomatic Lyme-positive dog owing to a lack of clinical signs. From time to time, however, an owner may insist on medical management for emotional or other reasons with the threat to go elsewhere if benign neglect is practiced. Again, it seems the dog-owner s viewpoint comes into play when managing CLB more often than it does for other disease conditions. Advocates for the screening of all dogs might say, among other things, that one might detect infection with B. burgdorferi prior to the onset of a very serious disease or that the hospital can gain important sero-prevalence data for their area. Regardless of any disease state, a positive test also serves as testimony to the fact that dogs are getting bitten by ticks! Opponents of the screening of healthy dogs argue that routine testing tends to over-diagnose disease leading to unnecessary treatments and the corresponding over-use of antibiotics in dogs that may have never become ill. In 2006, the ACVIM Small Animal Consensus Statement on Lyme Disease in Dogs: Diagnosis, Treatment, and Prevention was published. 46 The guidelines acknowledged the current controversies in the various areas of Lyme management, but were clear on the following points: Treating an asymptomatic Lyme-positive dog is not preferred, but should be made on a case-by-case basis. Doxycyline is the antibiotic of choice for treatment of Bb infection. Monitor all Lyme POS dogs for proteinuria. Dogs with proteinuria in endemic areas should be screened for exposure to Bb with antibody tests and worked-up if proteinuric. Approach #1 (Aggressive) Screen every dog (regardless of health) for Lyme (Bb) antibodies usually coupled with annual heartworm test.treat every blue-dot POS Lyme, regardless if asymptomatic at least once (initially). May or may not utilize Quantitative C6 testing to gauge response to antibiotic therapy. Approach #2 (Moderately Aggressive) Screen every dog (as above). Send out serum for Quantitative C6 test and treat per algorithm (<30 No treatment; >30 treat). Retest with Quant C6 periodic to measure C6 levels. Approach #3 (Conservative) Screen dogs for Lyme (Bb) antibodies ONLY if dog is symptomatic and exhibiting clinical signs consistent with CLB. Treat symptomatic dogs only. May or may not conduct Quantitative C6 testing. Top reasons why some veterinarians treat ALL asymptomatic Blue-dot positive dogs: 1) Dog is infected, why would you not? 2) Reduce spirochete-load in tissues. 3) Attempt to thwart infection during early tissue migration. 4) Owner demands it. 5) Would opt for treatment on own dog or own family member if knew infection status. 6) Cover Your Backside in the hope of preventing Lyme nephropathy. 7) Antibiotics are relatively cheap (used to be) and safe. 8) Have seen asymptomatic dogs feel better when empirically treated. 8

Top reasons why some veterinarians DO NOT treat asymptomatic Blue-dot positive dogs: 1) Treat a disease, not an antibody test result! 2) Signs and symptoms are readily treatable (if) they emerge at all. 3) Do not want to over-use antibiotics. 4) It is not done in human medicine. 5) Doxycycline and other antibiotics are not without their own safety issues. Should a Dog That Is Lyme Positive Be Vaccinated? The first question is Why should it even be considered? While we would expect a prior infection with a virus or bacteria to protect from future exposures (the booster phenomenon), infection with Borrelia burgdoferi does not fit the rule. As discussed earlier in this article, Bb has an incredible capacity to alter its appearance by changing the proteins on its outer surface which allows it to successfully elude the host s immune system. Unlike with other diseases (parvovirus, distemper, etc.) where antibodies from an infected dog will lead to the destruction of the virus, research has shown that serum taken from a dog infected with Bb does not contain the correct array of antibodies to kill Borrelia burgdorferi to any appreciable degree. 47 However if serum contains antibodies to one of Bb s most vulnerable outer surface proteins (OspA), Bb spirochetes are inactivated prior to leaving the tick. This is because OspA serves as an adhesive protein used by Bb to bind to a receptor within the tick mid-gut. 48 Prior to transmission, OspA disappears and this is why naturally infected dogs do not make antibodies against it. 47 However, a dog vaccinated with a Lyme disease vaccine containing OspA makes antibodies that attach to Bb while it is still in the tick rendering Bb unable to be transmitted. Since natural infection does little to build immunity, it is believed that Lyme-positive dogs (and people) are at risk for subsequent exposure to new Bb that are acquired by additional tick infestations. 49,50,51 For this reason, the decision to vaccinate a Lyme-positive dog has clinical merit in terms of attempting to thwart re-infection. To be clear, research has not been conducted to determine the forward-facing efficacy of any vaccine given to a dog with a current Bb-infection. Likewise, no controlled data exists to support the vaccination of Bbinfected dogs for the sole purpose of clearing dogs of their 46, 52 infection. The goal of vaccinating a Lyme-positive dog is to try to prevent future infection nothing else. Some argue that it may be unsafe to vaccinate a dog that is positive for Bb-antibodies based on concern about possibly precipitating Lyme nephropathy. Scant evidence in dogs exists to support this concern. Prior to the invention and routine use of patient-side antibody testing for Lyme antibodies, millions of doses of Lyme disease vaccines were administered to dogs (without knowledge of their Lyme status) without creation of untoward post-vaccinal kidney events. Based on the fact that one Lyme disease vaccine for dogs contains a single protein the OspA protein and no other Bb antigens, this vaccine may be more suitable to administer to a CLB dog if concern exists about adding additional Borrelia proteins to an already-infected dog. Summary Although canine Lyme borreliosis may vary in its prevalence throughout the U.S.A., it like many ticks and their diseases is venturing into new geographies each year. Canine Lyme borreliosis (CLB) can be emotional, confusing and time-consuming to veterinarian and dog-owner alike. Understanding the science, ecology and management tools associated with the successful prevention of CLB is important and will allow you to make more informed decisions for both your hospital and clients. Key Reminders: Lyme disease, more accurately termed CLB (Canine Lyme Borreliosis), is a tick-borne disease of dogs worthy of prevention. Although the prevalence of CLB varies by geography, ticks of all species are slowly moving into different areas of the U.S.A. Dogs regularly travel in and out of Lyme endemic areas and CLB should be on the list for any lame, feverish dog with a history of tick exposure. Year-round tick control is highly recommended regardless of whether CLB is in your area because other tick-borne diseases can have grave consequences on quality of life. Use quality educational resources to round-out the educational component of your CLB and tick-borne disease prevention strategy. CLB is the only tick-borne disease of dogs in the U.S.A. that has a vaccine to help prevent its occurrence. 9

RECOMMENDED RESOURCES: http://www.cdc.gov/lyme http://www.capcvet.org http://www.tickencounter.org http://www.petsandparasites.org/ www.dogsandticks.com References: 1 In, Physician s Guide to Arthropods of Medical Importance, 3rd ed. Boca Raton, FL: CRC Press; 2000: 311. 2 Bramn R. Tick-borne livestock diseases and their vectors: The global problem, In, Ticks and tick-borne diseases: selected articles from the World Animal Review, FAO Animal Production and Health paper #36, Food and Agriculture Organization of the United Nations, Rome, FAO 1983 (http://www.fao.org/docrep/004/x6538e/x6538e03.htm) (accessed on-line 9/7/11). 3 Lissman BA, Bosler EM, Camay H, et al. Spirochete-associated arthritis (Lyme disease) in a dog. JAVMA. 1984;185:219 220. 4 Gasser AM. Canine Rocky Mountain spotted fever: A retrospective study of 30 cases. JAAHA. 2001;37(1):41-48. 5 McQuiston JH, McCall CL, Nicholson WL. Ehrlichiosis and related infections. 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Effect of passive immunoglobulin transfer on results of diagnostic tests for antibodies against Borrelia burgdorferi in pups born to a seropositive dam. Vet Thera. 2008;9(3):184-191. 43 Krupka I, Straubinger RK. Lyme borreliosis in dogs and cats: Background, diagnosis, treatment and prevention of infections with Borrelia burgdorferi sensu stricto. Vet Clin Small Anim. 2010;40:1103 1119. 44 Töpfer K, Straubinger RK. Characterization of the humoral immune response in dogs after vaccination against the Lyme borreliosis agent: A study with five commercial vaccines using two different vaccination schedules. Vaccine. 2007;25:314 326. 45 Ticks can be Active in Winter Months. Companion Animal Parasite Council website. http://www.capcvet.org/recommendations/ticks.html. Accessed October 14, 2011. 46 Littman MP, Goldstein RE, Labato MA, Lappin MR, Moore GE. ACVIM small animal consensus statement on Lyme disease in dogs: Diagnosis, treatment, and prevention. J Vet Intern Med. 2006;20:422-434. 47 Straubinger RK, Chang Y-F, Jacobson RH, et al. Sera from OspA-vaccinated dogs, but not those from tick-infected dogs, inhibit in vitro growth of Borrelia burgdorferi. J Clin Microbiol. 1995; 33:2745-2751. 48 PAL U, desilva AM, et al. Attachment of Borrelia burgdorferi within Ixodes scapularis mediated by outer surface protein A. J Clin Invest. 2000;106:561-569. 49 Piesman J, Dolan MC, Happ CM, et al. Duration of immunity to reinfection with tick-transmitted Borrelia burgdorferi in naturally infected mice. Infect Immun. 1997;65(10):4043-4047. 50 Hovius KE, et al. A serological study of cohorts of young dogs, naturally exposed to Ixodes ricinus ticks, indicates seasonal reinfection by Borrelia burgdorferi sensu lato. Vet Q. 1999;21(1):16-20. 51 Nadelman RB, Wormser GP. Reinfection in patients with Lyme disease. Clin Infect Dis. 2007;45:1032 1038. 52 Appel MJG. A Model of Subunit Vaccines (Lyme Disesae). In: Proceedings of the Pre-Congress Symposium: The Future in Vaccinology. 1998, Buenos Aires, Argentina. 23 Johnson SE, Klein GC, Schmid GP, Feeley JC. Susceptibility of the Lyme disease spirochete to seven antimicrobial agents. Yale J of Bio Med. 1984;57(4):549-553. 24 Johnson J, Meeus P, et al. Abstract 109b: ANTIMICROBIAL ACTIVITY OF CEFOVECIN (CONVENIA ) AGAINST BORRELIA BURGDORFERI AND ITS IMPACT ON EARLY LYME BORRELIOSIS IN DOGS, Presentation was given at the ACVIM forum in New Orleans, June 1, 2012. SNAP, 3Dx, 4Dx and Lyme Quant C6 are registered trademarks of IDEXX. All rights reserved. AccuPlex is a registered trademark of ANTECH Diagnostics. All rights reserved. 10

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