EMERGING TRENDS IN VACCINATION PROTOCOLS
Moderator
Hugh Lewis, BVMS, MRCVS, DACVP Senior Vice President, Practice Development Banfield, The Pet Hospital Portland, Ore.
Participants
John Ellis, DVM, PhD, DACVP, DACVM Department of Veterinary Microbiology Western College of Veterinary Medicine University of Saskatchewan Saskatoon, Canada
Kathy Engler, DVM, DABVP Medical Advisor Banfield, The Pet Hospital Portland, Ore.
James Evermann, MS, PhD Department of Veterinary Clinical Sciences College of Veterinary Medicine Washington State University Pullman, Wash.
Karen Faunt, DVM, MS, DACVIM Medical Advisor Banfield, The Pet Hospital Portland, Ore.
Larry Glickman, VMD, DrPH Department of Veterinary Pathobiology School of Veterinary Medicine Purdue University West Lafayette, Ind.
Steven Levy, VMD Durham Veterinary Hospital Durham, Conn.
Will Novak, DVM, MBA, DABVP
Senior Vice President Chief Medical Officer Banfield, The Pet Hospital Portland, Ore.

A roundtable discussion sponsored
by an unrestricted educational grant
from Fort Dodge Animal Health 2004

LEADING EXPERTS EXAMINE THE PURPOSE OF VACCINATION, ITS BENEFITS, AND CURRENT PRACTICES. THEY ALSO DISCUSS EMERGING TRENDS IN VACCINATION PROTOCOLS, INCLUDING THE SAFETY AND EFFICACY OF A NEW CANINE VACCINE WITH THREE-YEAR DURATION OF IMMUNITY CHALLENGE DATA.

Dr. Hugh Lewis: When I was reading the April 1, 2004, issue of JAVMA last night, it seemed prescient that the first letter to the editor is titled "Calls for Vaccine Challenge Studies." It's written by Gary Norsworthy, DVM, DABVP, who makes a plea for challenge studies before adopting any new vaccination strategy. Today we'll talk about that very subject. Let's start by examining some preventive care and vaccination basics.
I think it's important to understand pet owners' perspectives of what they want for their pets. The answer is always the same; they want their pets to be happy, healthy, and long-lived. To deliver this, veterinarians must emphasize preventive care, and vaccination is a central component.
Purposes of vaccination
Lewis: Let's discuss the purpose of vaccination. We'd all agree it's an effective means of disease prevention. It's cost-effective, and it's far better to protect a pet from disease than to wait and treat the disease itself. Pets benefit greatly from vaccination, but widespread vaccination also decreases the prevalence and risk of disease in the pet population as a whole. The development of drug resistance by pathogenic organisms is avoided by preventing disease as well. Vaccination can also prevent pets from becoming a zoonotic threat to family members, especially immunocompromised individuals—the elderly, patients on chemotherapy or radiation therapy, and so on—a growing group and a health issue that needs attention. So those are the purposes behind vaccination from my perspective.
Dr. Will Novak: Vaccines have been so successful in preventing disease that many veterinarians think these diseases don't exist anymore. Every new generation bolsters this belief, and, eventually, vaccination becomes an optional procedure. A key point is that vaccines have been successful partly because they have been widely used.
Dr. John Ellis: I would echo the importance of herd immunity. I am concerned about the tendency to extrapolate between a few prospective studies and herd immunity as a whole.1-While these studies are a step forward and suggest that duration of immunity, for at least some vaccines, is more than one year, I do not think these studies constitute a basis for change, because they can't address the multiple factors affecting herd immunity and duration of immunity at the population level. I am concerned about changing protocols that have worked so well historically, and until everyone changes to a new protocol, it will be difficult to assess the efficacy of that protocol.
Dr. Steven Levy: I agree that group immunity is important. In my practice, the herd is a smaller herd of dogs; when it comes to Lyme disease, we're aggressive about vaccination, and we have eliminated it.
Before I would change my protocols, I'd want to see challenge study data to determine whether there is a reason to change. There is the big herd and the small herd—my own patients. I'm worried about the large herd and the protective barrier that keeps disease from spreading.
Dr. Larry Glickman: One aspect of herd immunity is that an infected animal that has been vaccinated is not only protected against clinical disease but sheds less virus and, therefore, is less likely to infect other animals. Traditional challenge studies look at the efficacy of the vaccine in terms of its ability to protect the individual animal, but it's also important to show that vaccinated animals don't shed the agent when challenged. Historically, that has been the problem with, for example, some of the older leptospiro-sis vaccines. They may block or prevent clinical signs, but many vaccinated and challenged animals are still infected and shed the bacteria in their urine. There are two distinct aspects of immunity—clinical protection and prevention of shedding.
Dr. Karen Faunt: In our practice, we still see parvovirus infection and distemper. It might be in isolated areas, but it's important for new graduates to remember that they don't have to go very far to find these diseases—only a few miles away in most cases.
Levy: When I travel and talk to veterinarians, I realize I am fortunate to be in a practice in which pets are well-vaccinated and clients are compliant. For example, when I visit an area and hear that 50% of a practice's pet population isn't vaccinated, I realize why veterinarians there are seeing parvovirus infection and distemper.
Glickman: We just completed a serologic study of mature Great Danes. We studied three categories: those that weren't vaccinated because the owners believed in holistic care, a group that was vaccinated as puppies and never vaccinated again, and the more traditional group that was immunized as puppies and then vaccinated yearly. To confirm those vaccine histories, we measured rabies titers. Sure enough, the dogs that were never immunized had no rabies titer, so we felt confident in their vaccine history. Then we looked at the parvovirus titers of these dogs. You might hypothesize that, if they were not immunized, they would not have titers. In fact we found no difference in the parvovirus titers between the dogs that had never been immunized, those that were partially immunized, and those that were fully immunized. This confirms that parvovirus is prevalent in the environment, and dogs are likely to be infected. Interestingly, none of those unvaccinated dogs that had parvovirus titers had a history of any parvoviral-like illness. Subclinical infection exists, but you wouldn't know about it unless you did a study like this. It is also a warning to be careful when interpreting titers in animals and trying to relate the titers to their immunization history.
Levy: I'd like to make two points. First, some dogs may have been infected with parvovirus and died, so they weren't in your groups. Also, antibody titers don't always indicate protection. With Lyme disease, for example, if the antibody titer results from natural exposure rather than vaccination, it is too late, because the animal is infected and at risk for the disease. If the titer results from a vaccine, which produces a protective antibody response, then the animal is protected. I question whether titers can routinely be correlated with protection.
Benefits of vaccination
Lewis: I think we are on the same page when it comes to the purpose behind vaccination. It leads to the next question: when should we vaccinate? We've already said we vaccinate to prevent or protect against infectious diseases that are associated with substantial morbidity and mortality. Recent graduates have possibly never seen distemper, hepatitis, or even parvovirus infection and may be forgiven if they occasionally ask why we vaccinate against these diseases. Is there sufficient risk to warrant vaccination? So why do we vaccinate?
Dr. James Evermann: There are two benefits to vaccination. The first is protection of the individual dog from developing a serious, life-threatening disease. The second is to decrease shedding of the infectious agent to cohort susceptible animals, such as pregnant dogs, puppies up to 4 to 6 months of age, and certain breeds with various levels of genetic predisposition to immunologic dysfunction. That is why it's vitally important to determine the risk category that the dog is in when preparing the vaccination program. Each dog is different; its vaccination programs and healthcare should be individualized. By vaccinating on a routine basis with canine distemper virus, parvovirus, and adenovirus, we are achieving protective levels of herd immunity. We are not eliminating the virus or low-level immune carriers, but we are maximizing the protection of dogs.
I'd argue that measuring serum antibody titers can be beneficial, but one must interpret the results with caution. Immune assessment profiling has been done for several years at Washington State University. Monitoring serum IgG titers to canine distemper and canine parvovirus is a good way of tracking the immune response and determining whether a booster is required at that time. We use a protective threshold of 1:100 or greater for both canine distemper virus and canine parvovirus. However, serum profiling doesn't correlate with protection for short-lived, localized infections, such as canine parainfluenza virus and canine coronavirus.
Novak: Vaccination is the only practical way we can protect pets from these lethal infections. And there are additional pathogens that cause morbidity but not mortality that we can protect pets from by vaccinating. As an example, you may be able to treat diarrheal disease, but wouldn't it be better to prevent it in the first place?
Dr. Kathy Engler: We talk about herd immunity, but we also have to think about the individual pet and the reality of the pet-family bond. A pet getting sick and dying from a preventable disease is unacceptable to the owners. If we don't protect pets against a disease that will shorten their lives, we have failed the pet and its family.
Lewis: Is that another reason to vaccinate—to protect the bond or to reflect the presence of the bond and the value of the pet?
Engler: Absolutely.
Levy: Ideal owners value their pets as family members, so they don't deny them care. It's a reason to give them maximum protection. It's an injustice to not offer something as effective and inexpensive as a vaccination—especially if it's not offered because of a misconception about either incidence of disease or duration of immunity. As Dr. Glickman said, those Great Danes were exposed to parvovirus, and, eventually, it hits the animal that is not just susceptible to infection, but is also likely to develop the disease. I don't want to see another case of parvovirus in my lifetime. The low incidence of disease or the impression that there is no disease is proof the vaccines are working.
Lewis: We have done a survey of distemper cases seen over the past two years in Banfield hospitals. We found 3,136 cases of suspected distemper (out of a population of 2.1 million dogs), which were supported by appropriate clinical signs, laboratory test results, or both. The disease distribution isn't uniform throughout the country, but we have identified the disease wherever we have hospitals.
Hepatitis and parvovirus infection
Lewis: Next, let's talk about hepatitis and parvovirus infection. Are we still seeing those diseases?
Novak: As Dr. Glickman mentioned, parvovirus infection is a persistent
problem. If we didn't vaccinate for it, the number of cases would likely increase dramatically.
Lewis: The incidence clearly varies from one area to another, but our data show plenty of dogs infected with parvovirus; 0.036% of all dogs seen at Banfield during 2003 were diagnosed with parvovirus disease.
Ellis: The profession has a poor hand on the prevalence and incidence of infectious disease, so this is valuable information.
Lewis: As an evidence-based practice, we need to be able to produce the dat to support what we are doing. For diseases like distemper, hepatitis, and pai vovirus infection, there is strong reasc to vaccinate. The diseases are still a substantial risk. As mentioned, there i also a reason to prevent chronic diseases that interfere with the quality of life and to prevent diseases that have zoonotic potential. What about coron avirus infection? Should we be vaccinating for that disease?
Coronavirus infection
Evermann: I'm an advocate of using canine coronavirus vaccine in high-ri: puppies and their dams. The concept core implies important, and noncore means not important. This is misleading, since canine coronavirus is an int gral part of the canine enteritis complex and can cause mortality in puppi that aren't infected with canine parvovirus. Canine coronavirus infection is also being reported more often in Australia, Japan, and various Europea countries. A major reason for the resu gence of these reports about canine coronavirus-related morbidity and mo tality is the fact that improved diagnc tics have enabled us to identify the virus more often. Previously, we relied on viral culture and electron microscopy, both relatively insensitive metl ods. Now we are using polymerase chain reaction (PCR) detection of canine coronavirus nucleic acid and
immunohistochemistry, looking for canine coronavirus antigens in tissue sections of gut from diseased dogs.
Ellis: In their recent Executive Summary and 2003 Canine Vaccine Guidelines and Recommendations, the AAHA task force suggested in the case of diseases that are of little clinical significance or respond readily to treatment, vaccines for those diseases may be identified as not generally recommended. Both of these criteria seem illogical to me. The idea that treatment is preferable to prevention seems inconsistent with increasing concern about the overuse of antibiotics and antibiotic resistance. And clinical significance is a relative term. Certainly we should be concerned about preventing severe or fatal diseases, but also about reducing morbidity and improving the quality of life. If we can do that through vaccination, as opposed to treatment, I think vaccination is preferable.
Faunt: 1 agree. Just because you can treat a condition doesn't mean you should not prevent it. Which one of us wouldn't prefer to prevent the common cold each winter rather than suffer through three to five days of misery? I think our pets would agree, even if it's a fairly mild condition, like mild diarrhea from coronavirus. Just because the condition isn't lethal isn't a reason to not prevent it if you can.
Novak: Cornell researchers studied coronavirus infection in dogs, occurring by itself.3 The mortality rate was zero. But when dogs were coinfected with parvovirus, the mortality rate increased significantly to 89%. This shows that combination infections are of great concern. Certainly, being able to prevent one or all of these diseases will improve the quality of life and decrease mortality and morbidity in patients. We can't look at each one of these conditions in isolation. With Giardia, coronavirus, and parvovirus infections, you can have dual or triple infections. There may be a number of parvovirus patients that we should also be treating for Giardia and coronavirus infections. Once veterinarians make the first diagnosis, they begin treatment and, usually, no other diagnosis is pursued.
Levy: The idea that we shouldn't bother to prevent a treatable condition is a terrible one, and it's common with human Lyme disease. Some veterinarians think it is easy to treat Lyme disease in dogs. But it is not easy to treat, especially Lyme-associated renal disease, which is almost invariably fatal. And an infected dog is infected for life. This brings me to the notion of core vs. noncore vaccines. That is a bad notion because it eliminates epidemiology. A core vaccine in Arizona is not necessarily a core vaccine in Connecticut or Wisconsin. Maybe the wotd should be "optional" or "appropriate to the epidemiologic situation." We can't ignore vaccines just because a disease seems to have an isolated range. Those ranges tend to expand over time.
Novak: According to the U.S. Census Bureau's report on geographical mobility for 2002-2003, 14% of all Americans move every year, and 40% take their pets on vacation, too, according to the National Pet Owners Survey. So this idea of regional diseases or regional exposure is suspect. We live in a global community, and even if you don't take your pet on vacation or relocate, the family next door, or at the park, or across the street does. By adhering to this regional notion, we are basically saying to clients, "Why don't you figure out where you will travel, and we can tell you how to vaccinate." Clients expect us to protect their pets. Unless you can do an extensive risk assessment on every patient, it becomes an inexact science.
Levy: My goal is to protect every pet under my care maximally. Vaccination certainly hasn't failed me, and I do not see it causing problems. To change the protocols that I've used successfully for 27 years is a big step and will require convincing scientific data.
Engler: Dr. Levy brings up a good point about protecting the pet against chronic disease sequelae, such as Lyme disease-associated nephritis, leptospirosis-associated renal failure, and bordetel-losis-associated coughing. Chronic diseases can weaken the pet-family bond and diminish the pet's quality of life.
Lewis: Dr. Glickman, I'm not sure you agree with this.
Glickman: I have a problem with a comprehensive policy of vaccinating all pets for every disease we can. We live in an age where we can expect—and we already see—more and more vaccines being marketed. If you argue that we should try to protect each animal to the fullest, it would obviate the concept of core and optional vaccines. Your argument seems to be that if we fail to vaccinate a pet for everything, then we haven't provided maximum protection. In that case, it is not a risk assessment. It is saying that every animal will be vaccinated for everything. If that's the policy, then there is no decision to make. You administer every vaccine on the market and make some argument for it, whether it is based on protection of that animal, protection of general health through herd immunity, or protection of an immunocompromised person living at home with the pet. Is that what you are saying?
Levy: It may have sounded like I vaccinate every dog and cat for everything, but I do, in fact, do risk assessment. For example, I don't administer
feline leukemia vaccine to cats that don't go outside and don't have contact with outdoor cats. I stress to those owners that they shouldn't bring a new kitten into the house until they isolate it and talk to me. For me, Lyme disease is a core vaccination. Yet there are some vaccines I do not use and probably will never use based on what is happening in my practice until I see data indicating other' wise. In some cases we are a little shy on risk assessment data, such as morbidity and mortality from some pathogens, and that is one of the problems.
Ellis: I certainly don't advocate vaccinating every animal with every antigen. What Dr. Levy alluded to is that the profession has done a good job of risk assessment without much direction and in the absence of data. It goes back to his 27 years of experience. What we have been doing has worked. So that is still my concern: changing from a protocol that works to a protocol that we're not sure will work, such as extended intervals between vaccination.
Lewis: One issue that bothers me is how we, as a profession, sometimes make sweeping judgments and changes in the absence of adequate evidence. I was at a hospital opening recently talking to a truck driver. He told me that half of the truck drivers on the road take their pets with them. They are crossing the country and exposing their pets to all sorts of environments, no
doubt picking up or depositing a variety of pathogens, parasites, and vectors. We tend to be naive, believing that we live in isolated and protected regions of the country and can make firm risk judgments on this basis. Our practice data suggest that, if a disease is endemic in one part of the country, then we see it almost everywhere, though the incidence may differ. We have heard so many clinicians say "it doesn't happen here," and suggest that even testing for the disease is inappropriate. We must stop thinking this way; if a disease is endemic to any area of the country, then it potentially occurs everywhere. This complicates risk assessment for individual pets, but perhaps it makes more sense to think of risk assessment for particular populations of pets rather than individual pets (e.g., rural, mobile, nonmobile). Then a practice could estimate the risk for pets in their locale and develop a general vaccination protocol that would apply across the board, with relatively few exceptions.
Ellis: That's an excellent point. The human population is moving all over the place. Take the severe acute respiratory syndrome (SARS) experience. How did SARS get from Hong Kong to Toronto? Most clinicians do not think about the population's fluidity.
Novak: One question is whether we can assess risk and change vaccine schedules based on the pet being indoors or outdoors. We interviewed 763 clients and asked that very question. The majority (70%) said their cats were indoor cats. Then we asked that 70% whether their cats had escaped during the past year or whether they had taken their cats on vacation—30% of this group said "yes."
I'm not saying you can't do risk assessment. It comes down to how extensively you would need to question a client to determine the individual patient's risk. How feasible is this in the exam room? Next, we need to consider what clients expect. They expect the pet to be protected from preventable disease. For
example, we have surveyed many thousands of clients and have learned that they have a very low tolerance for failure (i.e., pets developing diseases from which they could have been protected).
Engler: I think leptospirosis is a good example. A lot of veterinarians have stopped vaccinating because they don't think they see it in their region. Yet if you look at the literature over the last four or five years, veterinarians are finding more and more leptospirosis. Dr. Glickman noted that when he lectures about leptospirosis and veterinarians start looking for it, they find it.
Levy: That's a perfect example of if you don't look for a disease, you will never find it. If we are doing anything, we should be doing more surveillance, especially in areas where it appears there is no disease. As more rapid assays become available and as more diagnostic panels can be sent to laboratories or run in the office, then individual practitioners can do it. Since there is no Centers for Disease Control and Prevention (CDC) for veterinary medicine, a group as large and as widespread as Banfield could start collecting that information. You have the ability to look at tens of thousands of animals at a time.
Leptospirosis and Lyme disease
Lewis: In terms of risk assessment, one of the important elements has to be the risk posed by the vaccine. Some vaccines, especially those for bacterial diseases, have a reputation for producing a higher incidence of adverse reactions, and many veterinarians avoid using them. In fact, many dog breeders do not vaccinate against leptospirosis. Should we be vaccinating against leptospirosis and Lyme disease ? Are adverse effects a big issue?
Levy: There is no major safety issue proved to be associated with the original Lyme disease vaccine. Our 1993 JAVMA article is a safety and efficacy study involving Lyme disease vaccine in a naturally exposed canine population.4 We
found only minor adverse reactions in 38 of the 1,969 dogs that received 4,033 doses of the original Lyme disease vaccine in this multi-year study. Yet major adverse reactions are a common concern fueled by such sources as Internet sites and breeder newsletters. Supporting data for adverse events have not been collected, validated, peer-reviewed, and reported. What we are left with are anecdotal reports and opinions.
Lewis: Dr. Glickman, you've had experience with leptospirosis—would you talk about the adverse effects?
Glickman: Yes, we have to be cautious about dismissing reports of adverse reactions—whether it is from breeders or veterinarians—because, unlike the human medical profession, we don't have a well-developed, formal postmar-keting surveillance system for adverse reactions in animals. In fact, at the 2003 annual AVMA meeting, I met a veterinarian who works for the human vaccine adverse event reporting system in the CDC. She said there were more than 600 people involved in tracking adverse vaccine events in the federal government. They have the resources in place to identify a problem related to vaccine safety very quickly. We have no similar system in veterinary medicine. We rely on veterinarians and owners to passively report problems to the U.S. Department of Agriculture (USDA) or to the companies directly, which is uncommon. That is, only a small portion of all vaccine-associated events that actually occur are likely to be reported to the USDA or to the vaccine company. The bottom line is we don't have sound scientific data about the frequency or pattern of adverse reactions. I think practices like Banfield or Veterinary Centers of America have the infrastructure and resources, if they are interested, to collect such vaccine-associated adverse event information. Good scientific data are unlikely to be produced in the near future without the corporate practices making it a high priority.
Regarding leptospirosis, we certainly have heard over the years that leptospirosis bacterins (killed vaccines) are more likely to cause adverse reactions than other commonly used modified live canine vaccines. Considering the way most killed vaccines are made, there is a good reason for more adverse reactions. That is, they are often whole-cell products with many contaminants as well as adjuvants. I'm very positive about Fort Dodge's new leptospirosis bacterin, not only because it contains the right serovars based on prevalence and incidence, but because the company changed the technology to reduce the level of contaminants in the vaccine and, thereby, reduce the incidence of adverse reactions.
Lewis: You recently published a study in JAVMA on what appears to be a resurgence of leptospirosis.5 Does this reflect lack of vaccination or lack of vaccination against emerging pathogenic serovars?
Glickman: The resurgence we've seen in the incidence of leptospirosis among dogs since 1991 or 1992, particularly with Leptaspira serovars pomona and grippotyphosa, is not likely due to low vaccination rates in dogs, because these two serovars were not present in leptospirosis vaccines until only a few years ago. There has been a true reemergence of canine leptospirosis associated with new serovars, possibly due to changes in wildlife ecology. That is, serovars pomona. and grippotyphosa infect many species of wild animals, including raccoons, deer, and skunks. These wildlife species may have more opportunity today for contact with people and dogs, as more and more homes are built in previously wooded areas and more people attract wildlife to their yards by offering them food. This is why I think leptospirosis vaccines containing new serovars are so important now in controlling or reducing the rate of Leptaspira infection of dogs.
Lewis: So the cases we're seeing reflect infection with different serovars, not Leptaspira canicola or Leptospira ictero-haernarrhagiae?
Glickman: Absolutely.
Novak: Dr. Glickman, didn't you recently look at the incidence of leptospirosis in Philadelphia?
Glickman: We have data now from at least a dozen states, all showing the same epidemiologic pattern. That is, if a veterinarian knows
what to look for in dogs in terms of the clinical presentation, and then decides to test for leptospirosis by serology (microscopic agglutination test), 25% to 30% of those tests will be positive, whether they come from a suburban, urban, or rural area. Wherever we convince veterinarians to test for leptospirosis, they later say, "Guess what, we now have a
leptospirosis epidemic in our area." A lot of it is knowing when and how to test. We recommend veterinarians consider leptospirosis testing for any dog with signs of fever, vomiting, depression, and anorexia, as well as laboratory findings of renal or hepatic dysfunction or a coagulopathy associated with thrombocytopenia. Laboratory testing for leptospirosis is widely available and generally costs less than $50. Also, in addition to leptospirosis serology, a veterinarian can now ask for a PCR test to be conducted on a urine sample. The PCR test is probably more sensitive than the microscopic agglutination test during the acute disease.
Evermann: There seems to be an increase in the number of canine leptospirosis cases in the Northwest. This may be due to increased clinical recog-
nition, increased awareness of public health risks, changing ecology and epidemiology of Leptospira serovars, or a combination of these factors. In addition to the regular serovars, Leptospira bratislava had been the predominant serovar reacting in clinically affected dogs. However, since starting Leptospira autumnatis serovar testing in summer 2003, it has been our primary reacting serovar. More in-depth epidemiologic studies need to be conducted to validate these observations.
Lewis: So leptospirosis is a big problem. Since pets and people share the same home environment and leptospirosis is a zoonotic disease, it's important to vaccinate pets with effective vaccines.
Engler: In just the past year, Banfield has used more than 2.7 million doses of canine vaccines. Our reaction rate with the distemper combination vaccine that includes the four Leptospira serovars is 0.024%. Reactions range from mild fever and injection site swelling to anaphylaxis. For anaphylac-tic reactions alone, the incidence is 2.1 per 10,000 doses. I think Fort Dodge's Leptospira subunit technology is exceedingly safe. While many veterinarians don't report reactions to the USDA, Banfield has a standard reporting process for any type of reaction. In the
future, we should be able to generate some solid information regarding vaccine-related adverse events.
Novak: Do data exist that compare the reaction rate using the distemper combination vaccine with and without Leptospira antigens?
Engler: Not in our database. But Fort Dodge's reported incidence indicates that there is no significant difference in the reaction rate of the distemper combination with and without Leptospira antigens.
Glickman: There are practitioners who, particularly with the new vaccines, will see one or two reactions and not use the vaccine anymore.
Lewis: That's right. Clients or veterinarians sometimes have a negative attitude toward vaccination, either because they have seen a reaction or they have been told it is potentially dangerous. Whereas in our own experience, we have seen reactions, but they are relatively uncommon. We know how to deal with them, and it isn't a significant issue for us as a practice.
Levy: It factors into the entire risk-benefit issue. If the risk is the reaction, anything from injection-site swelling to anaphylaxis, and the benefit is not getting the disease, which may be fatal, it has to balance one way or the other. I think the risk of being exposed to the diseases for which we're vaccinating far outweighs the risk of vaccination. Most of the reactions are self-limiting or easily treated.
Glickman: We know that all vaccines may cause adverse reactions, both mild and severe, in a very small percentage of vaccinated animals. The rate of expected adverse reactions should always be factored into a risk assessment for vaccination for individual pets. Despite this, the generally accepted guideline is that all dogs should receive certain core vaccinations, such
as those for rabies, distemper, and par-vovirus infection. I think it's the right thing to do as a veterinary community. We have the obligation to say that every animal should receive vaccinations for rabies, distemper, parvovirus infection, and whatever else we believe is core for dogs based on the good of the general dog population, just as all children should receive mumps, rubella, diphtheria, and tetanus vaccinations. That is, we do a global risk assessment for the entire population, and usually do not make individual (animal by animal or person by person) decisions whether to vaccinate for these "core" diseases.
Novak: That's a good point. I don't think the veterinary profession has evaluated national risk assessment with all the factors that need to be included—it has been too narrow in scope.
Glickman: I've tried to create a generalized risk assessment that can be used for all canine and feline vaccinations. But if the process is too detailed, it becomes impossible to do on a case-by-case basis and veterinarians won't do it. On the other hand, if you design a simple process that provides a realistic risk assessment, some people criticize it, saying it's not detailed enough. So you're always trying to balance the two. We need to do risk assessment. Veterinarians are, in a sense, resistant to it unless they have a system they can use. I think it's too much to expect practitioners to create their own system for risk assessment.
Novak: Banfield's medical standards committee compared each vaccine component on the basis of disease incidence vs. safety. We've looked at preventive care on a national basis. This is certainly different than how the profession has approached vaccination in the past.
Lewis: To follow up on that thought, we also work in an environment that is standard for all our hospitals, but very different from most practices. Almost
all our hospitals are within PETsMART stores, and almost half their customers bring their pets with them. The store contains a pet adoption center, a grooming center, and a training center. So, our typical environment is a high-density pet area. And we deal with pets that are viewed as family members and share the home environment. The risk of zoonotic disease is very top-of-mind for us. Thus, our understanding of our practice environment contributes greatly to our vaccination and preventive care strategy. Rather than attempt to promulgate different vaccination strategies for different hospitals and regions, we consider that our patients are basically one population. Other practitioners would presumably develop a vaccination strategy reflective of their own practice environment.
Glickman: Banfield hospitals can do that because they provide veterinary care for approximately 2% of the pet population. The other 98% of pets, however, are seen by thousands of individual practices, and they don't necessarily follow uniform standards. Not every veterinarian will agree on the same outcome of a risk assessment when it comes to vaccination. I think that's OK and particularly true with Giardia and coronavirus vaccinations where there may be no one right decision that fits all dogs. There is no right or wrong. What is important is that veterinarians practice evidence-based medicine and articulate the reasons for their decisions to pet owners and the hospital staff.
Gidrdia infection
Levy: I'm going to speak now as the average small animal practitioner—I know so little about Giardia infection that I'm not sure what to do. I tested 67 dogs from the police canine unit and found that all the dogs acquired from Czechoslovakia were infected with Giardia, as were the dogs housed with them. But I don't know much about the general dog population in my practice area. So where do we go for this information so we can make our risk assessments?
Lewis: Good question. Should we be vaccinating for giardiasis?
Faunt: In our own study, we tested 7,500 pets for Giardia infection and up to 13% tested positive using a Giardia lamblia ELISA. The 15 hospitals tested 500 dogs and cats at each hospital with approximately 80% of the samples from dogs and 20% from cats—the number of positives varied from 3% to 13%, for an average of 7%. This study involved hospitals across the country in both urban and suburban areas. Only one-third of infected pets showed signs of disease. Two-thirds of the infected pets were asymptomatic, shedding into the environment, and possibly infecting other pets. Giardiasis is also potentially zoonotic.
You are right, most practitioners don't know the prevalence of Giardia infection in their regions. Only 16% of the ELISA-positive pets actually tested positive using fecal flotation. So if practitioners do the wrong test, they don't detect infection.
Engler: And the area with the highest infection rate—13%—was actually downtown Kansas City, Mo. So it was a distinctly urban environment.
Lewis: We must remember that Giardia species have zoonotic potential. The species affecting people (Giardia duode-nalis or lamblia) can also affect pets. You can't differentiate the species morphologically on fecal flotation or using the ELISA. Cysts can stick to the pet's hair, which is important considering the intimate contact between pets and people, particularly children. Shouldn't we be vaccinating for this disease?
Levy: I wonder how many cases of giardiasis I treat without knowing it. My standard therapy for a dog with diarrhea includes metronidazole—I know that this drug is an effective gastrointestinal anti-inflammatory. But perhaps
any dog on metronidazole therapy should be tested. I should know if the pet has giardiasis or not.
Faunt: Absolutely. That's important because if you are just treating with metronidazole, you may eliminate the clinical signs but not the infection. Metronidazole therapy alone is only effective in eliminating infection in approximately two-thirds of dogs. Additionally, pets can become reinfect-ed if their environment is contaminated. So these pets are likely still infected.
Novak: I read that one-third of Giardia cases are resistant to metronidazole now.6 Therefore, prevention by vaccination is a better approach than treatment
Levy: I'd like to ask a question about disease prevention: What is the threshold incidence level warranting a prevention program? I know it depends on the tendency of the disease to spread, but when do you implement a prevention program? Do you do it with 3% of your patients positive for Giardia species? Do you do it with 3% positive for Borreiia burgdorferi7. It is an important question for me because when I lecture to veterinarians in areas of emerging Lyme disease, I tell them that, in 1990, 3% of the dogs in south-em, coastal Maine were positive, and they had to live within five to 20 miles of the tidewater. Now Maine is endemic up the coastline to the mid-part of the state and also inland through
Maine and into New Hampshire and Vermont. Obviously 3% Lyme infection is an action level to get ahead of the infection. But when do I start recommending Giardia vaccination, and how do I get relevant epidemiologic data for my practice area?
Lewis: It's an interesting question. When do you prevent something? Do you wait for it to become endemic or do you try to prevent that from happening?
Glickman: You have to look at each disease individually. For a disease like Lyme, we won't decrease transmission by vaccinating dogs, but it is different for parvovirus. By vaccinating against pathogens like parvovirus, we aim to produce herd immunity. So there is nc one answer—each disease is different. You have to understand the dynamics of the disease and what the vaccine is going to do—Giardia infection is one of the most challenging. The prevalence of infection with this parasite is certainly higher in puppies and pet store animals, but it may not be highly transmissible between dogs and people. The most likely source of most human Giardia infections is contaminated water and not pet dogs. This does not mean, however, that a pet dog can't transmit Giardia to a person in the same household. A veterinarian, in conjunction with the pet owner, should decide whether Giardia vaccination is indicated for each pet. I do not believe there is enough evidence to justify this vaccine as core for all dogs.
Lewis: Our Giariiia incidence statistics, which vary from 3% to 13%, are in line with other studies. That would make Giardia one of the most common infectious organisms in the pet population.
Glickman: Of the organisms we test for. The prevalence of most organisms in dogs would probably increase if we systematically tested for them.
Lewis: That's right. A prevalent infectious disease with zoonotic potential deserves preventive attention.
Ellis: That brings up an interesting point about the need for vaccination at different life stages. Coronavirus is a great example. Based on research in livestock species, we know that coro-navirus is primarily a disease of the young. So why not focus on that age group for vaccination? And perhaps breeding bitches?
Evermann: I agree with Dr. Ellis. Canine coronavirus is primarily a disease-causing agent during the first nine weeks of the puppy's life. Maternal protection against canine coronavirus-induced disease is age-related. Colostral antibody wanes at about five to six weeks, which is the best time to vaccinate. The source of the virus is generally the puppy's own dam or a cohort adult dog shedding virus sub-clinically in the feces. The second most important age to vaccinate is the adult female who has puppies close by. Vaccination will decrease shedding periods from 15 to five days and reduce the viral challenge to the pups.
Glickman: You might be surprised that most puppies don't come from puppy mills or pet stores. The vast majority (over 70%) of owners buy their pets through a newspaper ad from a person who has had a litter in his home or from a breeder, or the owners bred a do§ themselves. Only a minority of dogs are purchased from pet stores via puppy
mills or are obtained from shelters. Thus, many of the dogs producing puppies that are purchased by new owners will be dogs that you probably do have an opportunity to see in your practice and for which you can provide preventive medicine to reduce the incidence of infectious disease and parasitism.
We hear a lot about puppy mills, shelters, and pet shops, but they account for only a small portion of new animals introduced into homes. These are the dogs most likely to be infected with parasites, such as Giardia and roundworms. But Giardia vaccine does not seem to be the answer to this problem.
Bordetella infection
Lewis: What about Bordetella infection? Should we be vaccinating for kennel cough? It is an irritating disease to the dog and certainly can decrease the quality of life. It is always a requirement at boarding kennels. I understand that Bordetella species can affect immunocompromised people. That combined with the discovery of Bordetella species that are resistant to certain antimicrobials is a cause for real concern.7
Evermann: Bordetella. and parainfluenza virus are both short-lived immunogens. They rely on IgA mucosal immunity for maximum protection and should be given twice a year in high-risk situations, such as boarding.
Novak: Dr. Glickman, you did a study on Bordetella infection, right?
Glickman: Yes. There are only two published field studies that I know of on the efficacy of the intranasal vaccine to prevent kennel cough. We published one of the studies in 19818 and the other one more recently.9 I deal with kennel situations where risk of transmission of organisms that cause kennel cough is most intense. Without vaccination in these environments, you can expect a 10% to 50% incidence of kennel cough. That incidence also applies to shelters and pet shops.
Bordetellosis is hard to control. Based on our studies, the intranasal vaccine is the most effective vaccine for the shelter or kennel environment. It will not prevent all kennel cough because the disease is caused by a variety of bacterial and viral agents. Most kennel cough vaccines only contain two or three of these agents, yet there are others that are important. I think you do need a good intranasal Bordetella vaccination program whenever you have a high density of dogs. However, it is also important to vaccinate pet dogs because they may contract kennel cough through contact with dogs in boarding kennels, in veterinary practices, and on the street. It is more important in some environments than in others, but all dogs should receive the intranasal vaccine at least yearly to prevent kennel cough.
Three-year duration of immunity challenge data
Lewis: We've had a good general discussion about vaccination, so let's move to the next topic, which is Duramune Adult, Fort Dodge's new vaccine offering a three-year duration of immunity for distemper, hepatitis, and parvovirus infection. Dr. Novak will review the results of the challenge study. Then we will talk in depth.
Novak: I'll give an overview of the challenge study, which was done to license the vaccine. The three components of the vaccine are distemper virus, adenovirus, and parvovirus antigens. For the distemper virus segment of the study, five dogs were given intramuscular vaccine, five dogs were given subcutaneous vaccine, and three dogs were controls. For the adenovirus segment, three dogs were given intramuscular vaccine, nine dogs were given subcutaneous vaccine, and two dogs were controls. For parvovirus, five dogs were given intramuscular vaccine, five dogs were given subcutaneous vaccine, and three dogs were controls. The study was performed over a three-year period. At the end of the study, the vaccinated
groups were challenged with the virus for which they were vaccinated. The controls in the group were challenged with the same virus.
In the distemper virus group, the vaccinated dogs either remained healthy or showed mild or transient signs of disease. The unvaccinated controls experienced severe illness, and two of the three died. In the adenovirus group, the results were similar. In the parvovirus group, all the vaccinated dogs once again exhibited good protection. Two of the dogs experienced mild vomiting at the peak challenge period. Unvaccinated controls showed moderate to severe signs of disease. The study appears to demonstrate protection for distemper virus, adenovirus, and parvovirus when vaccinated dogs are challenged after three years. The controls appeared to have been severely affected by the challenge, demonstrating that the challenge process was adequate.
Engler: And the researchers did measure liters as well to ensure that the controls had not been exposed to the infectious agent before the challenge.
Levy: Did the researchers measure titers on the vaccinants before they were challenged?
Engler: They did.
Levy: And did the vaccinants have circulating antibodies?
Lewis: Yes. It was on the basis of this challenge study that the USDA approved this vaccine.
Evermann: I'm pleased to see the generation of long-lived immunogens into the adult vaccination program. I have advocated this for a number of years. It will allow low-risk adult dogs to be vaccinated every three years without compromising their protection. High-risk dogs, such as show and breeding dogs with puppies, should be vaccinated more frequently. This is where practitioners will be doing risk assessments with their
clients to determine the frequency.
Glickman: To be licensed, a vaccine must show purity, potency, efficacy, and safety. The efficacy of the new Fort Dodge vaccine is apparent to me from the data we reviewed, but we can't determine safety based on this study. Usually new vaccines must also be tested for safety by practicing veterinarians using pet dogs. The usual tests would involve 400 to 600 dogs that are vaccinated according to label instructions and then followed
in the office and at home for possible reactions after vaccination.
Novak: The hypothesis is that the safety profile would be similar to that of the current distemper combination vaccine.
Lewis: The antigens in this vaccine have been used in marketed vaccines for many years. I understand that the concentration of antigens in this new vaccine is greater than in the previous distemper combination vaccines, but qualitatively they are identical.
Glickman: It may be the same antigen, but there may be other important issues. When the antigen concentration increases in a vaccine, so might the concentration of foreign proteins in the vaccine. You don't know the effect of such changes without a proper vaccine safety study that involves many more dogs than were included in the efficacy study. Also, efficacy studies are typically conducted in laboratory dogs, while safety studies involve pet animals.
Ellis: I don't think a 13-dog study is proof of efficacy in the larger pop-
ulation. The only thing that will constitute proof for me is if everyone uses the three-year vaccine, and we evaluate the results.
Lewis: I think the study shows efficacy, but it is not the same thing as efficacy in the field.
Ellis: I certainly agree that this study demonstrates efficacy in relevant challenge models, but the problem is making this, or similar studies, the basis for major changes in protocols that have worked in the field at the population level. That is because such experimental infections can't encompass all of the variation that determines vaccine efficacy in the field.
Levy: The reality is that even though I've heard people saying that only 5% of our colleagues are switching to three-year vaccine protocols, they are doing so with whatever vaccine they happen to be using. So if you want to switch to the three-year protocol, at least there is one vaccine that distinguishes itself because it has been challenged at three years.
Evermann: If practitioners want to assess immunity, they can monitor the immune response by checking serum antibody titers for canine distemper
virus and parvovirus. As mentioned earlier, I regard serum IgG levels of 1:100 or greater as reflections of protection for canine distemper virus and parvovirus.
Faunt: At some point, we have to move to the three-year protocol because we won't have evidence on population immunity until we do. We won't find out anything about herd immunity until the herd immunity changes.
Novak: But we do have a challenge study—a key piece of information many people have been waiting for. There is a licensed vaccine now that Fort Dodge will guarantee. I believe we have enough information to start using the vaccine in a broader trial.
Lewis: So is there general agreement that, as a challenge study, it certainly shows efficacy against these three antigens for a three-year duration?
Novak: Yes. I was really pleased to see a challenge study. We have questioned the correlation between protection and antibody titers, which was the focus of earlier studies. Now we finally have a challenge study that provides good evidence of an extended (three-year) duration of immunity.
Glickman: Do we know if these animals shed any of the challenge organisms? Are they contagious even though they are not clinically ill?
Also, duration of immunity challenge results for rabies vaccines that are licensed for three years are similar to challenge results for rabies vaccines that are licensed for one year. That is, if you vaccinate 1,000 animals for rabies and follow them for one or three years, not all of the vaccinated animals will necessarily be immune. I just don't want practitioners to get the idea that because 100% of a relatively small number of dogs were protected in this challenge study, that 100% of all vaccinated dogs in practice also will be solid ly immune at the end of three years.
That may or may not be the case and should be verified using serologic measures or epidemiologic studies.
Novak: However, it's true that at the time of licensing, most vaccines don't have tens of thousands of test cases in the laboratory or in the field. Once the science supports efficacy and safety, it makes sense to use the vaccine on a large scale, such as in a field trial.
Ban field field trial
Lewis: Banfield has taken the position for quite some time that we need evidence to support a change in our vaccination strategy. The evidence we need is laboratory-based studies with challenge data, plus extensive field trials. That is why we are conducting a clinical field trial involving 1,000 dogs. Between the Fort Dodge study and our study, we feel we can make an informed decision about whether or not to use this vaccine. We'll initiate the 1,000-dog field trial in the next few weeks. We'll monitor the dogs for any immediate adverse effects, acute and subacute, for the first 72 hours. Then we'll monitor for delayed adverse effects and, possibly, for protective antibody levels during the subsequent three years.
In addition to following the dogs given the three-year vaccine, we'll administer the current one-year vaccine to a cohort group matched for breed, age, gender, and hospital location. And we have historical data on adverse effects for comparison purposes. We have identified 25 hospitals that meet our quality performance standards, and each location will vaccinate 40 to 50 dogs with this new vaccine. They will also vaccinate many more with the current vaccine. So we'll have a cohort of matched controls that we'll monitor for three years. Our primary interest is in comparing the new vaccine with our current vaccine. The study will not be blind because we are dealing with client-owned pets, and we already have extensive adverse effect data on the current vaccine. The clients need to be fully informed in order to give their
consent, and we think this should be done by our veterinarians. The study will be done within the hospital setting, where we will have each pet available for at least the first four hours.
We think that this vaccine is an important development in preventive medicine. If the field trial results indicate that short-term effects are similar to our current distemper combination vaccine, we will adopt the vaccine for general use in our practice.
Levy: What other antigens will the dogs in the study be getting that day besides the distemper combination?
Lewis: Only the distemper combination.
Levy: This is not just a safety issue but also an efficacy study, isn't it? That's why you're performing it for three years.
Lewis: That's right. We're not only looking for delayed adverse effects, we'll be looking for disease development.
Levy: I'd like to point out that one of the most severe adverse effects of a vaccine can be failure to provide immunity and the resulting disease in the animal.
Novak: Assuming the safety profile of the new vaccine is the same as the current vaccine, there won't be any medical reason not to use the new vaccine for our preventive-care program. The leptospirosis portion, which has been part of the standard annual combination, will be a separate vaccine given annually.
Glickman: I hope you will be looking at the adverse reaction rates for the dogs that are in the annual vaccination group at years two and three.
Lewis: Absolutely.
Glickman: It may be that when you add up all the adverse reactions, it is three times greater with three doses than it is with one dose, as you would predict.
Lewis: That is exactly what we will be doing, and we'll be reporting annually on them as well.
Novak: That's a good point. When comparing three vaccinations to one vaccination over a three-year period, you have to consider all the potential adverse events associated with the multiple injections over the years. So we'll evaluate the reaction rate with the three-year vaccine, but there could be more reactions to a second or third dose of a one-year vaccine, also.
Evermann: I think the unified approach to assessment of clinical field trials will be very beneficial. If there is a breakdown in the herd immunity (at-large community of dogs), it will be detected early in this kind of active-surveillance approach. Likewise, if the vaccination frequency of every three years for the long-lived immunogens is controlling the street-level diseases, this will be made obvious as well.
Levy: I found it interesting that in the Fort Dodge study, the puppies were vaccinated with the new formulation at six weeks and nine weeks of age and then challenged three years later. Yet practitioners would still be using the existing Duramune Max formulations for puppies, and when the dogs come back in a year, they would use Duramune Adult and start the three-year cycle.
Lewis: The vaccine is positioned as a booster vaccine for adult dogs that have already been vaccinated as puppies. It supports a change in protocol from yearly revaccination to every three years.
Preventive care programs
Faunt: It's an exciting opportunity for us to rethink our preventive-care programs. The every six-month physical exam is very important, along with other preventive care procedures, such as heart-worm prevention, flea and tick prevention, vaccination, and fecal exams and deworming. This is an opportunity to do an even better job of preventive care.
Engler: We can go from being vaccination-driven to examination-driven. It's wellness diagnostics and early prevention. As a profession, we need to consider annual hematology and blood chemistry profiles, as well as routine urinalysis. Let's continue our heart-worm and feline leukemia testing. Emphasizing these services will result in better preventive care.
Novak: Rabies vaccine is administered every three years in many places, so this is just another set of antigens that can be given every three years. We still need to consider vaccinating for other diseases, such as leptospirosis or borde-tellosis on a yearly or twice-yearly basis.
Levy: Some of our concerns about shifting to the three-year protocol include difficulty getting dogs in for visits, decreased income, and shifting
doctor and team time to other purposes. How do you address these concerns and how will you stagger your vaccines?
Lewis: We have a preventive-care program, and vaccination is only one part of it.
Novak: From a client's perspective, the many components of a preventive-care program can be confusing. We need to make it simple, but owners also want their pets to be healthy and protected. Our wellness plans provide all the services necessary for optimum health (e.g., vaccination, health evaluations, dental care, parasite control). A patient may need all vaccinations in the plan or just some of them, but it's not a financial
question anymore. You can drop a particular vaccine from the program if it's not indicated, and there is no financial impact to the doctor or to the practice because it's just part of the package of care that we provide.
Levy: Your model is a wellness-based model with a preventive-care package. How do you address the veterinarian who has based his or her practice on vaccination visits with vaccination paying for the spays and everything else he or she gives away? That will be a hurdle for some practitioners. There has been a lot of discussion from our professional organizations and our veterinary schools about moving away from vaccine income, but there is less information on how to move away from it.
Novak: Look at the dental community. There was a time when cavities were the driver, and now the real driver is regular exams and cleaning. Advocating twice-a-year physical exams; trying to detect disease early; and emphasizing wellness, client education, and the value of the visit are what we need to move to in the veterinary profession. The dental profession has been very successful at that and, as a society, we are better for it, as demonstrated by our smiles and lack of cavities.
Levy: So the dog is brought in for that six-month appointment and receives, for example, its Duramune Adult, leptospirosis and Lyme vaccinations, and
ProHeart injection all at once. Six months later, it's brought in for Pro-Heart and the practitioner might say, "This is a wellness visit and we are going to do a general health profile, electrocardiogram, and a urinalysis." So that visit becomes more than just weigh the dog, give it an injection, and goodbye.
Novak: Valuable services need to be provided every six months, whether the dog is 1 year old, 2 years old, or 6 years old. I like to get baseline chemistry profile data on individual patients—that is the reason to do annual blood work. This provides data on an individual patient's normal CBC and chemistry profile range.
Lewis: For years I lectured on the sensitivity and specificity of clinical pathology tests and how using them blindly as screening tests didn't make any sense. Then I worked in the pharmaceutical industry where we routinely collected clinical pathology baseline data, which enabled us to define real changes reflecting disease, even when the data were well within the normal range. It is a huge advantage to have that data rather than just the normal range. So we have baseline data on many of our pets. And we have the capability, through our computer software, PetWare, to compare later values to them. It is not a matter of performing the evaluations to detect disease earlier, although that occasionally happens. Baseline data are collected so that when change does occur, it can be easily identified and interpreted.
Faunt: Part of my job is to take phone calls from our doctors who have questions about their cases. The most frequent question is about abnormal pre-operative blood work in an apparently healthy patient presented for a dental cleaning. I don't think a week goes by that we don't hear about an important problem detected in an apparently healthy pet through a wellness checkup—this may be from a physical exam, blood work, or an electrocar-
diogram finding. We are detecting disease earlier, and this is better for the pet and the client.
Lewis: Let's discuss the wellness package. What should it contain?
Glickman: We agree that, while there are core vaccines, there may be vaccines some animals don't need. Similarly, we should individualize wellness protocols. This becomes more important as we leam more about breed-specific problems. One example is the Scottish terrier—20% may get bladder cancer. Shouldn't we, therefore, recommend routine urine cytology for Scotties starting at 6 years of age to screen for bladder cancer? I think we already have enough information to tailor wellness evaluations to individual breeds, thus making our program better than a standardized wellness program that fits all dogs.
Lewis: That is exciting—that one can tailor a wellness program to certain breeds and situations. Excitement is also building about gene markers for different diseases. In the future, we'll be testing for those particular genes and tailoring the preventive-care program to that particular breed or family.
Glickman: Consider osteosarcoma in the large dog. We don't have a genetic test for it. We probably don't even have a good blood test yet. But those high-risk giant breed dogs should receive special yearly examinations, even if it's just palpation of the long bones or radiography. I think you need to design wellness programs that are tailor-made for specific breeds and individuals.
Lewis: We are on the cusp of a huge change in veterinary medicine, and that is evidence-based medicine. It will not be easy for individual veterinary practices to address, so we will need to address it collectively. At Banfield, we have a structure in place for evaluating the evidence for a new therapy, a new procedure, or a new diagnostic test, and deciding whether there is sufficient supportive evidence. New information needs to be confirmed and needs to fit with what's already known and understood. We have no collective mechanism in veterinary medicine for doing that. As a practice committed to evidence-based medicine, we have such a mechanism in place and are eager to help develop a library of knowledge that is supported by solid, confirmed data.
Novak: It's interesting that preventive care for pets hasn't been a dominant focus of our profession, particularly in veterinary education. If you look at human medicine and institutions like the Mayo Clinic, they are developing extensive preventive-care programs because it makes medical and financial sense. Early disease identification means there's a better chance for effective treatment.
Lewis: I agree. The same thing is starting to occur in pet practice. In our veterinary schools, we tend to focus on the reactive side of medicine, on the healing of disease problems. In pet practice, we are moving toward preventive medicine, as well as more sophisticated medical and surgical services. It is an exciting time.
What is clear to me is the great need for data. There are many reasons to follow large populations of pets, and there are many questions to address. We are aware that we may have a unique database at Banfield, a database of several million case records plus a high caseload that we can use in a prospective way. So we are conscious of the responsibility that comes with such a capability. We must share our data with our veterinary colleagues.
This hit home a few years back when a state VMA president admonished Banfield for testing for heartworm and prescribing heartworm preventive to 60,000 dogs—because heartworm didn't occur in that state. We had seen it spread to that state. It occurred to me that we really are in a privileged position. We are able to observe the dynamics of a disease and anticipate and follow where it spreads.
In conjunction with several organizations, Banfield is developing syndromic software that will help us identify disease hot spots and dynamics. Purdue University is one of the organizations; Dr. Glickman, perhaps you would like to describe how we are working with you?
Glickman: We made a case to federal agencies that this is an important database because it gives us a view of companion animals around the country. If people are likely to be affected by the release of a chemical, biologic, or radioactive agent, the agent is likely to have similar clinical effects in animals. There is no national human database comparable to the Banfield database for companion animals, so the CDC was impressed with this comparative medical approach to bioterrorism surveillance. It awarded nine grants this year, and one of them was given to Purdue University for the Banfield project. We want to identify how many animals in any given area we would expect to see with a particular problem; for example, acute bloody diarrhea. Eventually we will be able to download Banfield data weekly or daily and see whether we have an increased frequency of a specific clinical problems in a particular area, such as dogs with bloody diarrhea. That would alert Banfield to interact with veterinarians in the area, inform them of the development, and decide collectively what follow-up is needed. Do we need to contact the owners? Do we need to collect certain samples for additional testing? If the condition was occurring in both animals and people in the same area, we would alert the appropriate public health officials.
While the primary goal of our surveillance system is to detect environmental insults in pet animals related to bioterrorism, clearly it could also detect other types of naturally occurring diseases. Our focus is now on acute changes— i.e., conditions with rapid onset. By looking at the syndrome rather than the diagnosis, which may by delayed by two to three weeks, we can identify the problem weeks before veterinarians or anyone else in the community would recognize it. It's an amazing opportunity to demonstrate the value of the veterinarian to public health.
Novak: This is an exciting time in veterinary medicine. Initiation of new vaccine protocols is a small change, but one that can lead to many positive changes in terms of refocusing veterinary medicine on the bigger picture of healthcare.
References
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5. Ward, M.P. et d/.: Prevalence and risk factors for lep-tospirosis among dogs in the United States and Canada: 677 cases (1970-1998). JAVMA 220 (1):53-58; 2002.
6. Saunders Manual of Small Animal Practice, 2nd Ed. (Blood, D.C.; Studdert. V.P., eds.). W.B. Saunders, Philadelphia, Pa. 1988; p. 80.
7. Speakman, A.J. et at.: Characterization of antibiotic resistance plasmids from Bordetetla bronchiseptica. J. Antimicrck. Chemother. 40 (6):811-816; 1997.
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Sponsored by an unrestricted educational grant from Fort Dodge Animal Health.
The views in this publication represent those of the authors and do not necessarily reflect those of the sponsor or the publisher. Copyright © 2004 Fort Dodge Animal Health. All rights reserved.