Vaccinating Dogs Against Lyme Disease: Two Points of View

Vaccinating Dogs Against Lyme Disease: Two Points of View

The decision on whether to vaccinate dogs against Lyme disease remains an ongoing debate. Two veterinarians present differing viewpoints.

Meryl P. Littman, VMD, Diplomate ACVIM, University of Pennsylvania, & Richard E. Goldstein, DVM, Diplomate ACVIM & ECVIM (Companion Animal), The Animal Medical Center, New York City

Despite availability of a consensus statement and up-to-date canine vaccination guidelines (see Lyme Disease Vaccination Guidelines), the decision whether or not to vaccinate dogs against Lyme disease remains an ongoing debate among many veterinary professionals.

Today’s Veterinary Practice has gathered 3 experts to discuss this topic—Dr. Meryl Littman and Dr. Richard Goldstein evaluate the benefits and risks of vaccination, while Dr. Richard Ford outlines the current vaccination recommendations.

FIRST, DO NO HARM: LYME DISEASE VACCINATION MAY PRESENT MORE RISKS THAN BENEFITS

Meryl P. Littman, VMD, Diplomate ACVIM

When veterinary clinicians decide whether to recommend a particular vaccine for a particular patient, risks and benefits are weighed. The “vaccinometer” tool, developed by Larry Glickman, was designed to help practitioners determine whether or not to recommend a vaccine. 1

As we investigate Lyme disease vaccination, the questions posed by the vaccinometer help highlight many unanswered questions and potential risks related to this vaccine. With these concerns in mind, I choose “first do no harm.” In other words, if we use proper tick control, vaccination is unnecessary.

Question: What is the prevalence and risk of exposure/infection in your area (eg, infectiousness)?

Answer: Risk of Lyme disease exposure/infection is high in my area, but proper tick control lowers the risk greatly.

The CDC website 2 shows that 95% of human Lyme disease is found in 12 endemic states in the Northeast, Mid-Atlantic, and Upper Midwest U.S. In some endemic areas, seroprevalence in healthy dogs is as high as 70% to 90%. 3 In high-risk areas, risk of exposure can be lowered dramatically with adequate tick control, which also decreases the risk for other tick-borne diseases, such as anaplasmosis, babesiosis, bartonellosis, ehrlichiosis, and Rocky Mountain spotted fever.

Question: How great is the risk of severe disease once the dog is infected (eg, pathogenicity and virulence)?

Answer: Risk of Lyme disease becoming severe is low, but possibly somewhat higher in retriever dogs.

Less than 5% of seropositive (and seronegative) dogs had signs attributed to Lyme arthritis, 3 which generally responds rapidly to antimicrobial therapy. Perhaps 10% to 15% of treated dogs remain non-clinical carriers. 3 One study showed that 40% of dogs diagnosed with Lyme disease were misdiagnosed and had another condition instead. 4 Adult beagles experimentally infected with Lyme disease via tick exposure became seropositive but remained nonclinical, and exposed puppies showed only self-limiting signs of arthritis, anorexia, and fever, which did not require treatment. 3

Perhaps less than 2% of exposed dogs develop the more serious Lyme nephritis, 5 an immune-mediated glomerulonephritis, with high Lyme disease-specific antigen–antibody circulating immune complexes (CICs) and deposition in glomeruli, causing protein-losing nephropathy (PLN). 6 This entity has not been duplicated in any experimental model, and is seen mostly in Labrador and golden retrievers.

However, even in seropositive retrievers, Lyme nephritis is uncommon, 7 and we do not understand why some dogs develop it while many do not, despite their high titers and high CICs. It appears that a genetic predisposition exists, and that inflammation from Lyme antigens, and possibly inflammation from other infectious and inflammatory conditions, may be an environmental trigger. A genetic podocytopathy identified in soft-coated wheaten terriers 8 may predispose them to further glomerular damage; a similar condition may exist in affected retrievers.

In general, coinfections appear to result in more serious illness (eg, anaplasmosis/Lyme disease), which emphasizes the importance of tick control. 9

Question: How effective is the vaccine?

Answer: Not as effective as other vaccines we use.

Lyme vaccines appear to prevent seroconversion or illness in most (60%–86%) 3 vaccinates, but not consistently in all dogs, and not for a very long duration of immunity, thus annual (or even every 6 months 10 ) boostering has been recommended.

Question: How safe is the vaccine?

Answer: These vaccines are not as safe as other vaccines we use.

In the Banfield study of 1.2 million vaccinated dogs, the Lyme disease vaccine (monovalent bacterin), when used alone, produced more postvaccinal adverse events within 3 days than any other canine vaccine. 11 Adverse events associated with Lyme disease vaccine were described as “moderate” by an AVMA council in 2002. 12

All canine Lyme disease vaccines contain outer surface protein A (OspA), which attaches the spirochete to the tick’s midgut and is expressed on Borrelia burgdorferi while in the tick, and induces anti-OspA antibodies.

  • OspA without adjuvant is a polyclonal B cell mitogen that induces pro-inflammatory cytokines, 5 causes arthritis in rats, 13 and causes a strong TH1 response in people with HLA-DR4 haplotype, immune-mediated arthritis, and high anti-OspA antibodies after natural infection. 14
  • Lyme bacterin as well as OspA alone causes arthritis in hamsters 15 and sensitization 16 so that more severe arthritis is produced with boosters. 17
  • Lyme bacterins were not developed for humans since various Lyme disease antigens appear to have a role in post Lyme disease immune-mediated diseases. 18
  • In dogs with suspected Lyme nephritis, immunohistochemistry and elution studies have shown positive staining of glomerular immune complexes for a variety of Lyme antigens, including OspA and others, which are also found in Lyme disease vaccines. 5

Remember, inflammation or deposition may be delayed for months after vaccination and not seem temporally related nor recognized as a problem associated with vaccination.

Original reports of Lyme nephritis suspect cases 19 demonstrated that 30% had received Lyme disease vaccine, from 2 weeks to 15 months prior to illness. There is no experimental model for Lyme nephritis, which makes it impossible to study whether Lyme disease vaccine prevents, sensitizes, or aggravates it. However, since the most serious forms of Lyme disease are immune-mediated, I choose not to administer Lyme vaccine antigens that may elevate Lyme disease specific CICs (that increase after vaccination, as they should), which would circulate and need to be cleared (or deposited) for weeks to months after vaccination.

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In addition, should we vaccinate retrievers (some of which are genetically predisposed dogs) that may develop Lyme nephritis or PLN? These patients are most likely the very ones we should NOT vaccinate lest we add more complexes or sensitize them for a more intense immune-mediated reaction when they are boostered or exposed naturally.

Question: What is the potential for zoonotic spread to human contacts, and zoonotic spread to other dogs?

Answer: Potential for zoonotic transmission of Lyme disease is minimal.

B burgdorferi is transmitted via tick bites, and is not contagious from dogs to humans or dogs to dogs via excretions or blood transfusion. The reservoir hosts are wildlife, such as mice, small mammals, and birds. Seropositive dogs are sentinels that their human companions are at risk for exposure—not from dogs, but from ticks in the environment.

IN SUMMARY

The conclusions we can draw from the questions posed are:

  • Tick control is important: it prevents pets from acquiring the numerous tick-borne infectious agents, and prevents ticks from feeding on sentinel dogs, thereby acquiring the agent and transmitting it to their next host.
  • Most dogs exposed to B burgdorferi seroconvert, but are nonclinical and do not need antibiotics. 20 While most dogs do not exhibit illness after vaccination against Lyme disease, neither do dogs that are naturally exposed.
  • Dogs that have Lyme arthritis respond quickly to inexpensive/safe antibiotics.
  • Lyme disease vaccines have lower efficacy, shorter duration of immunity, and cause more post vaccinal adverse events than other vaccines we use.
  • Without an animal model for Lyme nephritis, we do not know if the Lyme disease vaccine prevents, sensitizes, or causes more immune complex deposition in kidneys, especially in genetically predisposed dogs.
  • Accordingly, the subset of dogs that possibly need the most protection (eg, retrievers) from the serious (immune-mediated) forms of Lyme disease may be the very ones predisposed to complications.

WITH TICK CONTROL & VACCINATION IN ENDEMIC AREAS, LYME DISEASE IS PREVENTABLE

Richard E. Goldstein, DVM, Diplomate ACVIM & ECVIM

Lyme disease, its causative tick-borne agent—Borrelia burgdorferi, and Ixodes ticks are all on the rise. In August 2013, the Centers for Disease Control and Prevention (CDC) increased their estimate of the number of new human cases of Lyme disease from 30,000 to 300,000 annually. 1

Tick removal and control is an important part of prevention of Lyme disease, but so is Lyme disease vaccination. No vaccine is completely without risk, but when weighing the risks versus the benefits, I believe the evidence strongly supports the following:

  1. In endemic regions, Lyme disease negative dogs should be vaccinated. As part of a Lyme disease prevention protocol, dogs must be vaccinated in addition to tick removal and control. One infected tick that escapes those first 2 barriers can easily cause infection. There is no evidence of any deleterious effects due to vaccinating Lyme disease negative dogs.
  2. In endemic regions, Lyme disease positive dogs with no clinical signs of disease should be vaccinated when risk of reinfection is high. There is no natural immunity due to previous infection, which likely results due to bacteria “hiding” themselves from the immune system, mainly in tissue, such as synovial membranes, and down-regulating immunogenic surface proteins. 2 In a recent paper on infections in humans with recurrent signs, it appeared that humans can be re-infected over and over again, almost annually, causing severe clinical disease. 3
  3. In endemic regions, Lyme disease positive dogs with clinical signs should be vaccinated when risk of reinfection is high, and should receive antibiotic therapy, prior to or immediately following vaccination.
  4. Lyme disease vaccination should be performed annually, with the currently available vaccines. In addition, tick control, even in vaccinated dogs, must be stressed to owners since very heavy exposure to Lyme disease may override vaccinal protection.

FACTS ON HUMAN VACCINATION

There is a race to bring a “new” human Lyme disease vaccine to market, with some vaccines already in advanced stages of development. 4, 5 A previous Lyme disease vaccine for humans had been approved for use in the U.S., but was removed from the market. The observation that this vaccine was unsuccessful due to lack of sales is often misused as an argument against canine Lyme disease vaccination.

The University of Pennsylvania’s world renowned vaccinologist, Stanley Plotkin, described the human vaccine situation in 2011: A vaccine against Lyme disease was licensed in the United States in 1998 but was subsequently removed from the market because of lack of sales. I believe that the poor acceptance of the vaccine was based on tepid recommendations by the CDC, undocumented and probably nonexistent safety issues, and insufficient education of physicians…The fact that there is no vaccine for an infection causing 20,000 annual cases is an egregious failure of public health. 6

FOUR SAFE & EFFECTIVE VACCINES

Compared to humans, dogs are lucky. There are currently 4 extremely safe, effective, and reliable vaccines 7-9 (Table) on the market that have all been through the United States Drug Administration licensing requirements for safety, efficacy, purity, and potency.

All available canine Lyme disease vaccines produce borreliacidal antibodies in the dog in response to vaccinal outer surface protein A (OspA). These antibodies work in the tick’s gut to bind the bacteria during the blood meal, sterilizing the gut of the tick and preventing transmission of bacteria into the dog.

OspC is the main immunogenic protein exhibited by Borrelia in the tick’s salivary glands and in the dog’s body during natural infection. Three of the current Lyme disease vaccines contain 2 strains of inactivated Borrelia isolates—1 OspA producing strain and 1 unique OspC producing strain, which perhaps adds an additional layer of protection.

EFFICACY OF THE VACCINE

These vaccines are extremely safe and, in conjunction with tick removal and control, prevent B burgdorferi infection and clinical Lyme disease, including Lyme nephritis.

The anecdotal evidence for this fact is overwhelming, but it has also been shown prospectively in multiple controlled studies in experimental infection and in the field. Following are just a few of many examples of such evidence in the field.

  • Levy showed excellent field efficacy of canine Lyme disease vaccination in 2003. 10
  • In 2010, Hebert and Eschner proved the efficacy of the Lyme disease prevention protocol, including vaccination in a large Rhode Island practice. 11
  • In a population of guide dogs in New York, implementation of strict tick control and mandatory Lyme disease vaccination regimen reduced the number of Lyme nephritis cases from approximately 10/year to less than 1/year over 7 years. 12
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COMBATING CONCERNS ABOUT VACCINATION

There are still some who believe that Lyme disease is not a disease “worth” vaccinating against or the vaccine causes more harm than good. This is despite the:

  • Extremely large number of clinical Lyme disease cases and nonclinical Lyme infections seen in small animal practice in endemic areas in the U.S., including the often fatal syndrome of Lyme nephritis
  • Millions of dogs that receive Lyme disease vaccines annually with no data to suggest any resulting harm from the vaccine.

Lyme Nephritis

Concerns have also been raised that vaccination can contribute to clinical signs of Lyme disease or the syndrome known as Lyme nephritis. 13 However, there is no evidence that Lyme nephritis is a vaccine-induced phenomenon or even commonly aggravated by vaccination.

In addition to the evidence from the case study in guide dogs, 12 I have evaluated or been a consultant on over 300 cases of dogs with Lyme nephritis; of these dogs, less than 10% were vaccinated. Moreover, I am not aware of a documented case in which a dog vaccinated against Lyme disease, but not infected with it, contracted Lyme nephritis. Ultimately, if we prevent Lyme disease, we prevent Lyme nephritis.

Adverse Events

It has been demonstrated experimentally that, upon vaccination of Lyme disease negative dogs, only a transient, relatively clinically insignificant rise in Lyme disease specific circulating immune complexes (CICs) occurs, and this rise lasts 8 weeks of less. 14 When Lyme disease positive dogs were vaccinated, CICs rose, but this rise was most likely much lower than that seen with new infection, and could likely be mitigated with antibiotic therapy, prior to or immediately following vaccination of Lyme positive dogs. 15

The alternative—not vaccinating Lyme disease positive dogs and risking additional Lyme disease infections—is very likely more detrimental than the possible rare negative effects of vaccination.

In the next issue of Today’s Veterinary Practice, Dr. Richard Ford will provide an in-depth discussion on Lyme disease vaccination guidelines in the Vital Vaccination column.

CDC = Centers for Disease Control and Prevention; CIC = circulating immune complexes; OspA = outer surface protein A; PLN = protein-losing nephritis

Meryl P. Littman, VMD, Diplomate ACVIM, is a professor of medicine at the University of Pennsylvania School of Veterinary Medicine. Her research includes canine tickborne diseases. She received her VMD from University of Pennsylvania.

Richard E. Goldstein, DVM, Diplomate ACVIM & ECVIM (Companion Animal), is chief medical officer at The Animal Medical Center in NYC. His research includes canine Lyme disease and leptospirosis. He received his DVM from Koret School of Veterinary Medicine, Hebrew University of Jerusalem, Israel.

todaysveterinarypractice.com

List of Dog Vaccines

Rabies, Leptospirosis, Hepatitis, and More

Vaccines are an important part of preventative health care for pets. Dogs are commonly vaccinated against some or all of certain diseases. Core vaccines should be given to all dogs, whereas non-core vaccines are given where indicated by your dog’s lifestyle or the geographic area in which you live.

With the exceptions of legal requirements for rabies or vaccination requirements for kennels or travel, many veterinarians recommend vaccinating adult pets every three years, as per the American Animal Hospital Association’s (AAHA) Canine Vaccine Guidelines. It should be noted, however, that an annual examination is still strongly recommended to make sure your pet remains in optimal health.

List of Core Dog Vaccines

  • Rabies:Rabies is a fatal viral disease that attacks the nervous system and that is contagious to humans.
  • Distemper:Distemper is a viral disease that is often fatal, affecting the respiratory and gastrointestinal tracts and often the nervous system.
  • Hepatitis/Adenovirus: A vaccination against adenovirus type 2 protects against both adenovirus types 1 and 2. Adenovirus type 1 causes infectious canine hepatitis, a viral disease that affects the liver and other organ systems, causing serious illness which is sometimes fatal. Adenovirus type 2 causes respiratory illness and may be involved in the development of kennel cough.
  • Parvovirus:Canine parvovirus is a viral disease that causes severe vomiting and diarrhea and can be fatal.
  • Parainfluenza: Parainfluenza is a viral disease affecting the respiratory system; may be involved in the development of kennel cough.

List of Non-Core Dog Vaccines

  • Bordetella: Bordetella is a bacterial infection that can cause or contribute to kennel cough.
  • Leptospirosis:Leptospirosis is a bacterial disease that affects several systems including the kidneys and liver; it can be fatal. It’s only a risk in certain geographic locations, so it’s not used routinely for every dog. Your vet can help you decide if your dog should have this vaccination.
  • Lyme Disease:Lyme disease is a bacterial disease spread by ticks that can cause arthritis and other problems such as kidney disease. It’s only a risk in certain geographic locations, so it’s not used routinely for every dog. Your vet can help you decide if your dog should have this vaccination.
  • Coronavirus: Coronavirus is a viral disease that primarily causes diarrhea. The risks of coronavirus infection are not as great as other viral diseases, so the AAHA’s Canine Vaccine Guidelines advise against routinely vaccinating for coronavirus. Your vet can help you decide if your dog should have this vaccination.
  • Giardia: The AAHA also recommends against vaccinating for giardia because the vaccine can prevent shedding of cysts but doesn’t prevent infection.​
  • Canine Influenza H3N8: The canine H3N8 virus, also called the Canine Influenza Virus (CIV), is a relatively new influenza virus in dogs. It causes flu-like symptoms in dogs and is very contagious when dogs are in close contact (i.e. kennel). Due to the contagiousness of this virus, some kennels, grooming salons, and similar businesses are now requiring this vaccination to prevent an outbreak. Aside from those situations, the decision to vaccinate your dog (or not) should be discussed with your veterinarian.

What Are the Letters in Combination Vaccines?

Viruses for which dogs are routinely vaccinated are often combined into a single shot as a combination vaccine (except the rabies vaccine, which is given separately). There are several different types of combinations vaccines available, and the individual components vary; they usually contain the core group of vaccines or the core with one or two other vaccines. Combination vaccines are often just called distemper or distemper/parvo vaccines, though there are more components than these. Each component is typically represented by an initial. What do all the initials mean?

  • D = Distemper
  • H or A2 = Adenovirus type 2; also protects against hepatitis (caused by Adenovirus type 1)
  • P = Parainfluenza (sometimes Pi)
  • PV = Parvovirus (sometimes simply abbreviated as P)
  • L = Leptospirosis
  • C = Coronavirus

For example, your dog’s certificate might state that along with its rabies vaccine, it received a DA2PPV vaccine. This means it was vaccinated for distemper, adenovirus (hepatitis), parvovirus, and parainfluenza viruses.

Other common abbreviations for combination vaccines include DHPPV and DHLPPV, among others.

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Puppy and dog vaccinations

Why does my dog need vaccinations?

Vaccinations protect your dog against killer diseases and they are likely to be a requirement if your dog goes into boarding kennels or travels abroad with you. Each injection can contain up to several vaccines against as many as seven different diseases.

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When should my puppy have his or her first vaccinations?

Puppies are normally safe from most infections for the first few weeks of their lives thanks to the immunity passed onto them through their mother’s milk. But they will normally need to start vaccinations between the ages of six to nine weeks. Several initial injections are required, followed by regular boosters which will need to be kept up to date for the rest of your dog’s life.

Until your puppy’s vaccination course is complete and active (follow your vet’s advice, but this is normally at between 11 to 13 weeks), they should not go to outside public areas, or any garden where an unvaccinated dog may have been. But during this time it is still important that your puppy starts learning how to socialise (that is, being familiar with a range of situations and experiences, and how to make friends with other dogs and people). Many vets now run special classes where puppies can learn to socialise with minimal risk of disease.

What if I don’t know if my dog has been vaccinated?

Respectable breeders will be able to give you this information, and good rehoming charities like Blue Cross will give a puppy a full vet check and provide up-to-date vaccines before they start their life as your pet. But, if for any reason you are unsure if your dog has had its vaccinations, consult your vet for advice. It does not hurt to repeat the course of injections. Blood tests to measure antibodies are sometimes suggested to find out if vaccinations are needed but the antibodies they measure may not be effective in preventing disease.

How often will my adult dog need booster vaccinations?

After your puppy’s initial vaccination course is complete, he or she will need a follow up injection every year. Which vaccines are given will depend on your dog’s general health and the prevalence of disease in the area you live. For instance, the leptospirosis vaccine needs to be given every year but parvovirus and distemper may only be needed every three years. Your vet should provide you with a vaccination record card so that you know when your dog is due to have his or her boosters.

What diseases do the usual vaccinations protect against?

Parvovirus: Parvovirus is a highly infectious disease that is often fatal and is very costly to treat. It is spread through contaminated faeces of affected dogs, and can remain active in the environment for anything up to nine months. The virus causes severe vomiting and diarrhoea which leads to a dog or puppy becoming very weak and dehydrated. The disease is more prevalent in certain parts of the country than others, so vaccination frequency advice may vary.

Click here for more information on prevention, symptoms and treatment of parvovirus.

Canine distemper: This virus is spread by an infected dog’s saliva and occasionally urine, and is normally contracted through direct contact. Initial symptoms include fever, eye and nose discharge, poor appetite and coughing. As the disease progresses, it can cause vomiting, diarrhoea and the skin on the paw pads to become hardened. In later stages, the central nervous system can be affected, causing symptoms such as seizures, limb weakness and imbalance. Serious cases can be fatal, and if a dog recovers it may suffer fits and ongoing health problems. There is no medicinal cure, only prevention. Dogs with the virus will be given supportive care to help their bodies fight the virus and treated with fluids to prevent dehydration and medication to help control seizures.

Click here for more information on prevention, symptoms and treatment of canine distemper.

Leptospirosis: This is a serious, life-threatening disease which can progress quickly and lead to organ failure. It is spread through the urine of infected animals, which can contaminate water or soil. The disease enters the body through the eyes, nose, mouth or broken skin. Symptoms include excessive thirst, fever, vomiting, muscle pain and infertility. The disease can also infect humans. Antibiotics can treat the disease, but there will often be long-term health complications.

Adenovirus 1 and 2: This is a viral disease with two strains, the first of which causes hepatitis, an infection of the liver (also known as Infectious Canine Hepatitis). The second strain causes a respiratory illness which is a type of kennel cough. In both cases the disease is transmitted through saliva, urine, faeces, blood or nasal discharge of infected dogs and the virus can survive for many months.

Are there any other vaccines my dog might need?

Kennel cough: Kennel cough is not usually dangerous, but can be a nuisance. Some of the viruses which can contribute to kennel cough are included in a dog’s core vaccines, but the actual cause is a bacterium, and a separate vaccination is available for this. It’s likely that you’ll need this if your dog is going into kennels. It has to be given into the nose and is only protective for six months.

Click here for more information about kennel cough.

Rabies: Although rabies is not a required vaccine for dogs in the UK, it is if you’re planning on taking your dog on holiday with you to another EU country. Your dog will need to be at least 12 weeks old and already microchipped to have the jab. The injection is a requirement, among others, of getting a Pet Passport, which allows you to take your dog to another EU country and bring him or her back to the UK.

How much will vaccinations cost?

Your puppy’s initial set of vaccines will cost between £30 and £60, but this is far less than the cost of treating the diseases themselves. It will also save your dog from pain, discomfort and even death, and means that you and your family will be spared the stress of coping with a seriously ill pet. Regular booster vaccines will cost less than the initial vaccinations.

If you are on benefits and live in an area covered by Blue Cross, you may also be eligible for help with veterinary care. Click here to find out more about our veterinary services.

www.bluecross.org.uk

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