WSAVA Vaccination Guidelines 2024 PDF

2024 guidelines for the vaccination of dogs and cats – compiled by the Vaccination Guidelines Group (VGG) of the World Small Animal Veterinary Association (WSAVA) AUTHORS:...

2024 guidelines for the vaccination of dogs and cats – compiled by the Vaccination Guidelines Group (VGG) of the World Small Animal Veterinary Association (WSAVA) AUTHORS: R. A. Squires *,1, C. Crawford†, M. Marcondes‡ and N. Whitley§ *Formerly, Discipline of Veterinary Science, James Cook University, Townsville, QLD 4814, Australia † College of Veterinary Medicine, University of Florida, 2015 SW 16th Avenue, Gainesville, FL 32608, USA ‡ Department of Clinical Medicine, Surgery and Animal Reproduction, São Paulo State University, Rua Sergipe 575, ap. 32, São Paulo, 01243-­001, SP, Brazil § Internal Medicine, Davies Veterinary Specialists, Manor Farm Business Park, Higham Gobion, Hertfordshire, SG5 3HR, UK 1 Corresponding author email: [email protected] Journal of Small Animal Practice © 2024 WSAVA 1  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Contents Executive Summary.....................................................................................................................3 Introduction................................................................................................................................4 The Purpose of WSAVA Vaccination Guidelines...............................................................................5 Vaccines as Part of Comprehensive Preventative Health Care.........................................................6 Different Types of Vaccine............................................................................................................6 Effects of Maternally Derived Antibodies on Immunisation..............................................................7 Serological Testing of Dogs and Cats to Assist in Vaccination-­Related Decision-­Making....................8 Current and Emerging Topics in Canine and Feline Clinical Vaccinology............................................9 Canine Vaccination Guidelines....................................................................................................11 Feline Vaccination Guidelines.....................................................................................................16 Vaccination of Dogs and Cats in Shelters and Sanctuaries...........................................................22 Adverse Events Following Vaccination (AEFVs).............................................................................24 Frequently Asked Questions (FAQs).............................................................................................27 References...............................................................................................................................36 2 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License EXECUTIVE SUMMARY The World Small Animal Veterinary Association (WSAVA) Vaccination Guidelines Group (VGG) was convened to develop guide- lines for the vaccination of dogs and cats intended to be helpful to veterinarians globally. Previous guidelines, published in 2007, 2010 and 2016, have been cited in the peer-­reviewed scientific literature several hundred times and downloaded tens of thousands of times. The present document is an updated version of these guidelines. The VGG recognises that its recommendations must be broad and based on fundamental immunological principles because detailed recommendations about vaccines and vaccination of dogs and cats that might be suitable for some countries or regions may be much less applicable elsewhere. Guidelines are intended to provide broad guidance for veterinarians in decision-­making. They do not describe mandatory or mini- mum standards of care. These guidelines can be used by national and regional veterinary associations and individual veterinarians or veterinary practices to develop their own vaccination schedules suitable to their own local conditions. Notwithstanding this, the VGG strongly recommends that ALL dogs and cats should receive the benefit of vaccination. This will not only protect individual animals but will improve “herd immunity” to help minimise the risk of contagious disease outbreaks. With this background in mind, the VGG has defined core vaccines as those that ALL dogs and cats should receive, after considering their lifestyle and the geographical areas in which they live or to which they travel. Some core vaccines protect animals from potentially life-­ threatening diseases that have global distribution while others protect against life-­threatening diseases that are prevalent only in particular countries or regions. Core vaccines for dogs in all parts of the world are those that protect against canine distemper virus (CDV), canine adenovirus type 1 (CAV) and canine parvovirus type 2 (CPV). Core vaccines for cats in all parts of the world are those that protect against feline parvovirus (FPV), feline calicivirus (FCV) and feline herpesvirus-­1 (FHV). In areas of the world where rabies is endemic, vaccina- tion against rabies virus should be considered essential for both dogs and cats (i.e. rabies vaccines are core in those places), even if there is no legal requirement for this. Leptospirosis in dogs is another life-­threatening, zoonotic disease that is widely distributed around the world. In countries or regions where canine leptospirosis is endemic, where implicated serogroups are known and where suitable vaccines are available, vaccination of all dogs against leptospirosis is highly recommended and the vaccines should be considered core in those places. In many parts of the world, feline leukaemia virus (FeLV)-­related diseases are endemic. In these places, FeLV vaccines should be considered core for young cats (3 years earlier were less likely to have protective antibody titres against CDV and CAV than geriatric dogs vaccinated 1 to 3 years earlier. Serological responses of these geriatric dogs to revaccination were not studied. Nevertheless, on the basis of these findings, revaccination of aged pets triennially or perhaps more frequently can be recommended. Studies of UK dogs and cats vaccinated for the first time against rabies for pet travel have shown clearly that many aged animals fail to achieve the legally required antibody titre (Kennedy et al., 2007; Mansfield et al., 2004). Younger animals were more likely to be successfully immunised. Medical records documentation At the time of vaccine administration, the following information should be recorded in the patient’s permanent medical record: Date of vaccine administration; Identity (name, initials or code) of the person administering the vaccine; Vaccine name, lot or serial number, expiry date and manufacturer; Anatomical site and route of vaccine administration. The use of peel-­off vaccine labels and stamps that imprint the medical record with the outline of a pet facilitate this type of record-­ keeping, which is mandatory in some countries. Any adverse events should be recorded in a manner that will alert all staff members during future visits. Informed consent should be documented in the medical record in order to demonstrate that relevant information was provided to the client and that the client authorised the procedure (e.g. for “off-­label” use of vaccines as discussed above). At the very least, this notation should indicate that a discussion of risks and benefits took place before vaccination. The VGG recommends that vaccination certificates be designed to include not just the dates on which vaccines were administered, but also a field for the veterinarian to state how long into the future the animal is expected to be protected by vaccination. This will help diminish confusion in the minds of pet owners and kennel/cattery proprietors. DIFFERENT TYPES OF VACCINE New kinds of vaccine have been developed and marketed since the last WSAVA vaccination guidelines were published (Day et al., 2016). However, globally, the well-­established vaccine types remain predominant and important, especially modified live and inactivated kinds. 6 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Modified live or live attenuated vaccines contain live but attenuated (i.e. weakened) whole viruses or bacterial organisms that can attach to cells, infect them and replicate within them, establishing a low-­level and transient infection that engenders a strong immune response, without causing overt disease. Modified live vaccines are generally more immunogenic than most other kinds. Many MLV vaccines are particularly potent. They typically require fewer doses to achieve a strong immune response. Some modified live vaccines generate a consistent and long-­lasting immune response (for many years) after a single dose, when administered to an animal in the absence of MDA interference. MLV vaccines have the advantage of more effectively inducing immunity at relevant anatomical sites when administered parenterally (usually subcutaneously) and are more likely than most other kinds to induce robust cellular as well as humoral (antibody-­mediated) immunity. Some modified live vaccines are administered directly to mucosal sites (e.g. intranasal or oral vaccines) where they induce local, protective mucosal immunity. Inactivated (or killed) vaccines contain entire, inactivated, antigenically complete microorganisms that are not able to infect or repli- cate, but are able to stimulate an immune response. As they do not mimic a natural infection, they usually produce less potent immune responses, may not produce adequate mucosal or cellular immunity, and generally require multiple doses and an adjuvant to stimulate an adequate immune response. However, some inactivated vaccines are unusually potent, for example killed rabies virus vaccines. Some of these are highly immunogenic and can induce long-­lasting protection after a single dose. Seroconversion of kittens after a single dose of inactivated vaccine has also been shown for FHV and FPV vaccines in kittens (Lappin, 2012). In a subsequent FHV challenge study (Summers et al., 2017), an inactivated vaccine provided similar protection to a MLV vaccine after challenge on day 7 after vaccination. However, most inactivated vaccines are thought to require at least two initial doses to immunise, regardless of the animal’s age. The first dose generally primes the immune response and the second (and sometimes a third) dose, usually administered 2 to 4 weeks apart, provides the protective immune response. A full protective immune response may not develop until 2 weeks after the second or final dose is given. Inactivated vaccines usually engender a shorter DOI when compared to MLV vaccines, and more frequent revaccination (i.e. boosting) is needed to maintain protection. Subunit vaccines consist of antigenic sub-­components of pathogenic microorganisms that have been extracted and purified from cultures or have been synthesised using recombinant DNA technology (i.e. gene splicing and protein expression). These vaccines tend to be less immunogenic than MLV vaccines, so usually contain an adjuvant and engender a shorter DOI, like most inactivated vaccines. There are subunit vaccines for Lyme disease (Eschner & Mugnai, 2015; Grosenbaugh et al., 2018) and more recently for Bordetella bronchiseptica (containing fimbrial antigens), marketed for use in dogs (HPRA, 2024; MSD Animal Health, 2024). Recombinant DNA technology has recently been used to produce a novel live recombinant vaccine against CPV (Pearce et al., 2023). The novel CPV component is combined with a more conventional MLV CDV component (European Medicines Agency, 2021). This vaccine is intended to protect puppies against CPV infection at a very young age (4 weeks) by breaking through MDA interference more effectively than previous generation vaccines. This vaccine contains a recombinant, chimaeric parvoviral genome, part CPV-­2c and part CPV-­2. During manufacture, the recombinant genome is used to produce live parvovirus that can infect cells and multiply in vaccinated puppies, just like a conventionally manufactured live attenuated vaccine. Vectored vaccines are another kind of recombinant vaccine, in which one or more genes that encode immunogenic proteins of one or more pathogens are cloned directly into the genome of a vector virus or organism (e.g. an attenuated canarypoxvirus vector with the rabies virus surface glycoprotein gene spliced into place). This avian recombinant, chimaeric virus can replicate only to a very limited extent in the mammalian host but does express the introduced gene(s) on host cell surfaces, mimicking a natural infection. Vectored vaccines cannot revert to virulence and the vector is chosen to be non-­pathogenic and sometimes immunostimulatory. These vaccines can induce both humoral and cellular immune responses, usually without the need for an adjuvant. Attenuated canarypoxvirus has been used in vectored vaccines against rabies, canine distemper and FeLV infection. Nucleic acid-­based vaccines (DNA and RNA vaccines) are relatively new forms of vaccine created by manipulating nucleic acids to produce copies of viral antigenic target proteins upon immunisation. Messenger RNA (mRNA) vaccines have become familiar to many people during the current COVID-­19 pandemic. They generally require very cold transportation and storage. Messenger RNA vaccines employ delivery systems, such as lipid nanoparticles, that protect the nucleic acid from degradation and that allow cellular uptake and mRNA release. DNA is much less fragile than mRNA, so naked DNA vaccines are more robust. There are currently no mRNA vaccines, nor naked DNA vaccines, available for use in dogs and cats. EFFECTS OF MATERNALLY DERIVED ANTIBODIES ON IMMUNISATION MDA are mostly acquired by neonatal puppies and kittens by consuming colostrum in the first hours after they are born (Chas- tant & Mila, 2019; Rossi et al., 2021). MDA provides passive immunity. Although important to protect puppies and kittens in the first weeks of life, MDA can also interfere with the ability of the young animal to mount its own, active immune response to most vaccines (DiGangi, Levy, et al., 2011b; Friedrich & Truyen, 2000). Serum MDA inhibits immunoglobulin G (IgG) production within the young animal and prevents vaccine antigens from stimulating an active immune response. In most pup- pies and kittens, MDA declines to levels that allow an active immune response to vaccination by about 8 to 12 weeks of age. Puppies with low amounts of MDA may be vulnerable (and capable of responding to vaccination) at an earlier age, while others Journal of Small Animal Practice © 2024 WSAVA 7  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License FIG 1. How maternally derived antibody (MDA) interferes with a veterinarian’s ability to immunise puppies or kittens through early vaccination. This graph shows a puppy’s serum antibody (Ab) concentration or “titre” on the vertical axis and age in weeks on the horizontal axis. The antibody shown happens to be against canine parvovirus, but the same principles apply in both puppies and kittens to a variety of pathogenic agents. Shortly after birth, this puppy acquired a substantial amount of anti-­parvoviral antibody from its mother, via colostrum. This is the so-­called “maternally derived antibody” or MDA (the red line). MDA declines exponentially with a half-­life of approximately 9 to 10 days. The syringe icons represent repeated vaccinations, the first of which was given at 6 weeks of age. This first vaccination did not immunise the puppy because of interfering MDA, which neutralised the vaccine. The same is true of the next two vaccinations. At 8 weeks of age, this puppy became susceptible to parvoviral enteritis, because its MDA concentration fell below the level required to protect from a moderate challenge with canine parvovirus. Yet it could not be immunised at that age, because the level of MDA was still sufficient to interfere with the vaccine and to prevent active immunisation. By approximately 13.5 weeks of age, the level of MDA in this puppy fell low enough to permit immunisation. At 16 weeks of age, the puppy was revaccinated and promptly made its own active immune response (the blue curved line). The pink-­shaded rectangle between dotted lines represents the “window (or period) of susceptibility” for this puppy, during which it was susceptible to parvoviral disease. It is not recommended to routinely measure MDA in very young puppies. Some puppies might receive more or much less than did this puppy. So this is why repeated vaccinations are given every 2 to 4 weeks, to narrow the “window of susceptibility” for puppies and kittens as much as practicable. Ab Antibody, MDA Maternally derived antibody; syringe icon, vaccination. may possess MDA at such high levels that they are incapable of responding to vaccination until ≥12 weeks of age (Friedrich & Truyen, 2000; Thibault et al., 2016). The period when MDA is insufficient to provide complete immunologic protection, but still enough to interfere with an active immune response, is known as the “window of susceptibility” for the puppy or kitten. During this “window,” a puppy or kitten cannot be immunised by conventional vaccines but is susceptible to disease if it comes into contact with “street” or virulent pathogen. It is not possible, without serological testing, to predict when this “window” will open or close (i.e. begin or end) because the amount of MDA transferred to individual puppies or kittens varies between litters and within litters. As it is impossible to predict, without blood testing, when sufficient waning of MDA will occur, the initial core vaccination series usually involves the administration of multiple, sequential doses. The repeated doses are not booster doses. They are applied with the aim of triggering an active immune response as soon as possible after MDA has dropped sufficiently (see Fig 1). MDA can interfere with immune responses to both modified live and inactivated vaccines. If, when administering the first dose of an inactivated vaccine, there is enough MDA to block an active immune response, immune priming will not occur. A second dose of inactivated vaccine would then fail to immunise the animal. Conversely, a single dose of MLV vaccine given after MDA has waned sufficiently is usually sufficient to immunise. SEROLOGICAL TESTING OF DOGS AND CATS TO ASSIST IN VACCINATION-­RELATED DECISION-­ MAKING An advance in companion animal practice is the commercial availability of in-­practice diagnostic test kits that can detect antibod- ies against CDV, CPV and CAV in dogs and FPV in cats. Some of these test kits have been validated for use in practice and shelter settings and are simple to use (Egerer et al., 2022; Gray et al., 2012; Litster et al., 2012; Meazzi et al., 2022). They provide a rapid result (positive or negative) within 20 to 30 minutes. Some of these test kits may usefully complement traditional laboratory-­based methods (e.g. virus neutralisation and haemagglutination inhibition testing), which remain the “gold standards” for serological testing (Jenkins et al., 2020). For CDV, CPV and CAV in adult dogs and FPV in adult cats, the presence of serum antibody provides evidence of an active humoral immune response, which is very likely to indicate protection from disease. In some pets, these antibodies persist for 8 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License well over 3 years. Vaccinated dogs may maintain protective immunity against CDV, CPV and CAV for many years (Bohm et al., 2004; Jensen et al., 2015; Mitchell et al., 2012; Mouzin et al., 2004a, 2004b; Schultz, 2006; Schultz et al., 2010). The same is true of FPV in cats. Conversely, the presence of antibody against FHV or FCV is currently not considered to be a reliable predictor of immune protec- tion against either of these viruses (Egberink et al., 2022; Stone et al., 2020) although an earlier study did provide supportive results in shelter cats (DiGangi et al., 2011a). Vaccines intended to protect against FHV and FCV cause seroconversion but may only provide partial protection against disease and do not protect effectively against infection or development of the carrier state. In cats, tests for anti-­FPV antibodies are considered more reliable indicators of protection than tests that detect anti-­FHV and anti-­FCV antibodies (Mende et al., 2014). As opposed to the presence of antibody, the absence of detectable antibody does not reliably predict susceptibility to infection and disease. This is because cellular and innate immunity are not evaluated in antibody detection testing and many animals are thought to be robustly protected by immunological memory in the absence of detectable serum antibody (Killey et al., 2018). In support of this, prompt, strong anamnestic antibody responses have been demonstrated in previously vaccinated, seronegative pet animals shortly after revaccination, indicating that they would likely have been robustly protected from challenge (Mitchell et al., 2012; Mouzin et al., 2004a, 2004b). Despite these findings, absence of antibodies has generally been taken as a clinical indication for revaccination. This is based on a precautionary principle because proof of memory (other than retrospectively by revaccination and retesting) cannot readily be achieved in most clinical settings. An owner may wish to confirm that a puppy or kitten has mounted an active immune response after the course of primary vaccinations has finished. If so, a serum sample taken at or after 20 weeks of age and at least 4 weeks after the last vaccine dose can be tested. Animals discovered to be seronegative (probably only a small percentage) should be revaccinated and retested sev- eral weeks later. If the animal again tests negative, it should tentatively be considered a non-­responder that may be incapable of developing protective immunity against the pathogen(s) for which it tests seronegative. Performing a gold standard serological test at this stage may refute the earlier in-­practice results or show a low or undetectable antibody titre typical of a non-­responder dog (see Fig 2). In-­practice serological test kits have gained favour with some veterinarians who wish to offer their clients a convenient alternative to routine revaccination at (for example) 3-­yearly intervals. However, in-­practice serological test kits have been shown to vary in sensitiv- ity, specificity, positive and negative predictive value (PPV and NPV), and overall accuracy (OA) when compared to reference, gold standard tests (Bergmann et al., 2020; Bergmann, Halzheu, et al., 2021a; Bergmann, Zablotski, et al., 2021b; Dall’Ara et al., 2021; DiGangi, Gray, et al., 2011a; Egerer et al., 2022; Meazzi et al., 2022; Mende et al., 2014). The specificity of in-­practice serological test kits needs to be high if they are to be relied upon (Bergmann et al., 2020; Berg- mann, Halzheu, et al., 2021a; Bergmann, Zablotski, et al., 2021b). A false positive result would suggest that an animal has antibodies and is protected. In fact, because the result is a false positive, current guidelines recommend that the animal should be revaccinated. Recently, several different in-­practice diagnostic test kits were compared with gold standard testing in Germany (Bergmann et al., 2020; Bergmann, Halzheu, et al., 2021a; Bergmann, Zablotski, et al., 2021b). The kits varied in ease-­of-­use and in performance relative to the gold standard tests. Some of the tested kits performed very well for detection of CPV-­2 anti- body in canine serum (Bergmann et al., 2020) but kits for detection of CDV antibody, and a kit for detection of CAV antibody, performed much less well (Bergmann, Halzheu, et al., 2021a; Bergmann, Zablotski, et al., 2021b). Four different in-­practice kits for detection of CDV antibody were compared to a gold standard. Against the gold standard, they were not reliable when used to test dogs with acute illness or healthy-­looking dogs with chronic disease (Bergmann, Zablotski, et al., 2021b). The reliability of the gold standard virus neutralisation test for CDV, when used in acutely ill or chronically diseased dogs, was also questioned in this paper. Overall, the usefulness of in-­practice serological testing for detection of anti-­CDV antibody using these test kits, certainly in acutely ill dogs or in dogs with chronic disease, was not supported by this work (Bergmann, Zablotski, et al., 2021b). A single test kit for detection of anti-­CAV antibodies had poor specificity (Bergmann, Holzheu, et al., 2021a). Further research is needed to boost progress in this important area. Understanding the utility and limitations of serological testing as an aid to vaccination-­related decision-­making is demanding. Vet- erinarians should not feel obliged to start using serological or “titre” testing in their practices, if they are not inclined to do so. Several FAQs dealing with serological testing have been included in this latest version of the guidelines. These are for those veterinarians who may be interested in exploring this topic further. CURRENT AND EMERGING TOPICS IN CANINE AND FELINE CLINICAL VACCINOLOGY Most of the contemporary issues discussed in the 2016 version of these guidelines (Day et al., 2016) remain of current interest although many further topics and issues have emerged since then. Since 2016, concerns about a low proportion of all pets receiving the benefit of vaccination have grown in some countries (Malter et al., 2022; Taylor et al., 2022). A low proportion of vaccinated pet animals adversely impacts “herd immunity” (Datta & Roy, 2022). The concept of herd immunity needs to be understood and acted Journal of Small Animal Practice © 2024 WSAVA 9  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License core MLV vaccines finished at 16 weeks or older CAV and CPV at > 20 weeks of age, dose of vaccine for Repeat serology no less Revaccinate against CDV, CAV and than 4 weeks later CPV years This puppy may be a serological if it cannot respond non-responder to one of the three Cellular and or innate immunity Could be inadequately for this puppy protected FIG 2. Algorithm showing the recommended approach to interpreting and acting upon serological test results obtained >4 weeks after the last puppy or kitten vaccination at 16 weeks of age or older. Ideally, serological testing, especially testing for anti-­CDV antibodies, should be done in a reference laboratory, not using point-­of-­care testing. CAV Canine adenovirus, CDV Canine distemper virus, CPV Canine parvovirus, MLV Modified live virus upon by companion animal veterinarians. Frequent revaccination of a small proportion of pets within a population will do little to improve herd immunity. Conversely, increasing the proportion of vaccinated pets within the population, even if each of those pets receives only a single, well-­timed core vaccine, will achieve far more. Excessive, unwarranted “vaccine load” remains of concern and, indeed, the situation has deteriorated in some countries. Multi-­ component vaccines that contain a mixture of core and non-­core components remain common. In at least one country, monovalent vaccine choices have diminished rather than expanding, as would be preferable. The concept of “One Health” has never been more pertinent to companion animal practice than it is today. The suffering of humans and the suffering of their companion cats and dogs have been interwoven during the COVID-­19 pandemic (Baptista et al., 2020). Just as the pandemic delayed elective surgical and medical procedures in countless humans, it prevented pet owners from obtaining timely veterinary care, especially vaccinations, for their pets (Owczarczak-­Garstecka et al., 2022). Thankfully, that situa- tion has improved in many countries since the beginning of the pandemic. There have been many other One Health implications of COVID-­19. A renewed global focus on pandemic preparedness is an opportunity for the One Health initiative, since many potential human pathogens either have animal reservoirs or equivalent animal pathogens. Further, new vaccine platform technologies used for human pathogens may catalyse innovative veterinary vaccine development. “Vaccination hesitancy” is another issue of considerable contemporary importance. Concerns about worsening vaccine hesitancy have been expressed by members of both veterinary and medical organisations (Lee et al., 2022; Mattson, 2020). Vaccine or vac- cination hesitancy has been described as a “…delay in acceptance or refusal of vaccination despite availability of vaccination services.” (MacDonald, 2015). Vaccine hesitancy is of enormous and growing concern to public health authorities around the world, including the World Health Organization (WHO). Indeed, in 2019, vaccine hesitancy was listed as one of the top 10 threats to global human 10 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License health (WHO, 2019). The phrase “vaccine hesitancy” first appeared in the Web of Science Core Collection in 2010. Since then, use of the phrase has increased substantially with more than 350 papers on this topic published in 2020 alone (Squires, 2021a). The description provided above is not sufficiently inclusive for small companion animal practitioners. This is because many people who choose not to vaccinate their pets do so without ever consulting a veterinarian. They do not delay acceptance, nor refuse, they simply avoid any discussion (Squires, 2021b). There are scant data on vaccine hesitancy in small companion animal practice, but over 2500 veterinary practitioners in numerous countries responded in an informal survey and the results indicated that it is perceived by many veterinarians as a growing problem (Squires, 2021b). In support of this, data about many aspects of companion animal welfare collected in the United Kingdom from 2011 to 2022 (PDSA, 2022) began to reveal an alarming decline (first noticed in 2017) in the proportion of UK pets reported by owners as being vaccinated. In the PDSA’s 2019 PAW Report only 72% of owners reported that their puppy had received a primary course of vaccines (down from about 88% in 2016). The figure was lower for kittens: 61%, down from about 82% in 2016. The proportion of adult dogs and cats receiving regular booster revaccinations was even lower. In 2020 to 2022 (PDSA, 2022), the situa- tion seemed to stabilise or improve, with slightly larger proportions of animals receiving vaccines, but the confounding effects of the COVID-­19 pandemic make it difficult to interpret these more recently reported figures. In the 2019 PAW report, “It’s too expensive” was a top reason for not having vaccination done (17% of all pet owners). For owners of adult cats, not wanting to stress the cat by taking it to the veterinary clinic was a powerful inhibitor to seeking revac- cination, slightly more powerful than cost (influencing 22% of owners versus 21% influenced by cost). Thus, Fear Free Pets® and other similar organisations may be able to play important roles in improving compliance with vaccination recommendations. Interestingly, concern about vaccine safety was not mentioned as a reason for failure to vaccinate pet dogs or cats in the 2019 PAW report. In a recent study of almost 1 million UK dogs, Taylor et al. (2022) showed that only 49% had received at least one vaccine against leptospirosis in the 12-­month study period. In this study, Dogs over 8 years of age were 12.5 times less likely to have received the benefit of vaccination against leptospirosis than were dogs under 1 year of age. Another recent study looked at variability in non-­core vaccination rates of dogs and cats in veterinary clinics across the USA (Mal- ter et al., 2022). These animals were all up to date for their core vaccines. Nationally, in this study, median clinic vaccination rates for dogs were 70.5% for leptospirosis and 68.7% for Bordetella bronchiseptica. In cats, for FeLV, median clinic vaccination rates were reportedly low for adult cats (34.6%) and only slightly higher for kittens and 1-­year-­old cats (36.8%). Clearly, there remains considerable scope for veterinarians and veterinary associations to work to improve small companion animal vaccination rates, including in some rather wealthy countries. Regarding excessive “vaccine load” it is disappointing that, for example in Australia, it is no longer possible to purchase a mon- ovalent FeLV vaccine. The situation has deteriorated since the last iteration of these guidelines. The only option now is to inject a pentavalent, inactivated vaccine that includes FeLV. Previously there were several monovalent choices. Presumably, commercial imperatives in a relatively small market have led to this situation. CANINE VACCINATION GUIDELINES Core vaccines for pet dogs Summary information about core vaccines for dogs not living in shelters is provided in Table 1. Information about the different kinds of vaccine (e.g. MLV, inactivated, recombinant) is provided in an earlier section of these guidelines. Core vaccines for dogs that are relevant throughout the world protect against disease caused by CDV, CAV and CPV. In addi- tion, veterinarians working in certain places designate other vaccines as core, for example those that protect against rabies and leptospirosis. Wherever rabies is endemic, all dogs and cats should be vaccinated for the protection of both pets and humans even if legislation does not require this. Mass canine vaccination has been shown to greatly reduce or eliminate rabies cases (Zimmer et al., 2018). Leptospirosis is another life-­threatening, zoonotic disease that is widely distributed around the world. In countries or regions where canine leptospirosis is endemic, implicated serogroups are known, and where suitable vaccines are available for use, vaccination of all dogs against leptospirosis is highly recommended and these vaccines should be considered core in those places. The VGG recommends initial vaccination of puppies against CDV, CAV and CPV at 6 to 8 weeks of age, then every 2 to 4 weeks until 16 weeks of age or older. The more frequently these vaccinations are given, the narrower (or shorter) will be the “window of susceptibility” for the puppy. Vaccinating more frequently than every 2 weeks is not advised. It follows that the number of these primary core vaccinations will vary somewhat and will depend on the age at which vaccination is started and the chosen intervals between vaccinations. The most important of these early vaccine doses is the one administered at 16 weeks of age or older. MDA can be expected to have waned substantially by that age in a large majority of puppies, so almost all puppies should be able to respond to vaccination then, if not before. Journal of Small Animal Practice © 2024 WSAVA 11  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Table 1. Vaccines for pet dogs (non-­shelter) Vaccine Puppies ≤16 weeks Dogs >16 weeks Revaccination Comments and recommendations Core vaccines for pet dogs, all parenteral Canine parvovirus-­2 Start no earlier than Two doses 2 to 4 weeks Consider revaccinating These core vaccines are among (modified live 6 weeks of age. apart are recommended at about 6 months the most important received virus, MLV)+canine Revaccinate every 3 to by some manufacturers of age, rather than by puppies and dogs. The aim distemper virus (MLV or 4 weeks until 16 weeks However, a single dose waiting until the dog should be to vaccinate as large recombinant)+canine of age of MLV or recombinant is 12 to 16 months as possible a proportion of the adenovirus-­2 (CAV-­2, In especially high-­risk vaccine will likely protect of age. This will entire population MLV) situations continue until most dogs narrow the window of Careful socialisation of puppies 20 weeks of age and susceptibility for any (during their sensitive period consider vaccinating every puppies that failed for socialisation) can begin 2 to 3 weeks to mount an active before the completion of this immune response vaccination series earlier Thereafter, revaccinate at 3 years of age and thereafter no more frequently than every 3 years Canine parvovirus-­2 Administer a single dose This recently introduced product (recombinant)+canine from 4 weeks of age is aimed specifically at distemper virus (MLV) before commencing young puppies, likely to have routine primary interfering MDA, rather than for vaccinations revaccination of older dogs Rabies (inactivated) Follow any local laws or Follow any local laws or Follow any local laws Core wherever the disease is regulations as a priority. regulations as a priority. or regulations as a endemic or wherever local laws Follow the product leaflets Follow the product leaflets priority. Follow the or regulations require of locally manufactured of locally manufactured product leaflets of vaccines. In some vaccines locally manufactured countries, the first dose is vaccines. generally not given before Revaccination at 12 weeks of age 1 year of age (or in some countries 1 year after the primary vaccination) is required. Canine rabies vaccines with either a 1-­or 3-­year DOI are available. Timing of boosters is determined by the licensed DOI, but in some areas may be dictated by law Leptospira spp. (killed Initial dose is usually from Two doses 2 to 4 weeks Annually Core for dogs in regions bacterin). The 8 weeks of age. Follow apart where canine leptospirosis serogroups included in the advice in the product is endemic, implicated vaccines depend on the leaflet about when to serogroups are known and geographical region. start. A second dose is suitable vaccines that include Most vaccines include at given 2 to 4 weeks later implicated serovars are least two serogroups, but commercially available some are monovalent, some trivalent and some quadrivalent Non-­core vaccines for pet dogs Canine Parainfluenza Virus Administer from 6 weeks of Two doses 2 to 4 weeks Annually Non-­core (CPiV, MLV, parenteral) age onwards, then every 2 apart are generally The duration of immunity to 4 weeks until 16 weeks recommended by provided in pet dogs is of age or older manufacturers uncertain. Use of CPiV (MLV-­ mucosal) in combination with Bordetella bronchiseptica may be preferable as CPiV is not broadly available as a single antigen product 12 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Table 1. (Continued) Vaccine Puppies ≤16 weeks Dogs >16 weeks Revaccination Comments and recommendations Bordetella bronchiseptica Each of these mucosally A single dose Annually Non-­core (live avirulent bacteria, applied vaccines provides These live vaccines intended intranasal) protection after a single for intranasal or oral B. bronchiseptica+CPiV dose administration MUST NOT (MLV) intranasal Some can be applied as be inadvertently injected B. bronchiseptica+CPiV early as 3 weeks of age, parenterally as this may lead to (MLV)+CAV-­2 (MLV) others at 7 or 8 weeks of a severe adverse reaction intranasal age. Follow the product B. bronchiseptica (live leaflet advice avirulent bacteria, oral) B. bronchiseptica+CPiV (MLV) oral Bordetella bronchiseptica These parenteral bacterin or Two doses Annually for most. Non-­core (killed bacterin, subunit vaccines require Review and follow the Review and follow the These vaccines intended parenteral) two doses to immunise, specific product leaflet specific product leaflet for parenteral use should Bordetella bronchiseptica generally given 2 to intervals as there are intervals not inadvertently be given (cell wall antigen extract, 4 weeks apart. Review differences between There are special intranasally or orally. This parenteral) and follow product leaflet products revaccination would not be effective and Bordetella bronchiseptica intervals instructions for the might cause unnecessary (fimbrial antigen, fimbrial antigen discomfort parenteral) vaccine Borrelia burgdorferi (Lyme These parenteral bacterin or Two doses 2 to 4 weeks Annually. Revaccinate Non-­core. Generally borreliosis; killed whole subunit vaccines require apart. Review and follow just before the start recommended only for use in bacterin, parenteral) two doses to immunise, the specific product leaflet of the tick season, as dogs with a known high risk of Borrelia burgdorferi generally starting at about intervals determined regionally exposure, living in or visiting [subunit-­Outer surface 8 weeks of age. Review regions where the risk of vector protein A (OspA), and follow the specific tick exposure is considered parenteral] product leaflet intervals to be high, or where disease Borrelia burgdorferi is known to be endemic. The (subunit OspA and mainstay of Borrelia prevention chimaeric OspC proteins) is diligent ectoparasite control. Direct dog to dog transmission does not occur Canine influenza virus These parenteral, Two doses. Review and Annually Non-­core. Licensed only in USA. (H3N8; killed adjuvanted, inactivated viral vaccines follow the specific product Consider for use in at-­risk parenteral) require two doses to leaflet intervals, generally groups of co-­housed dogs such Canine influenza virus immunise. The initial dose 2 to 4 weeks apart as those in kennels, dog shows (H3N2; killed adjuvanted, can be given from 6 weeks or day care parenteral) of age. Review and follow Canine influenza virus the specific product leaflet (Bivalent H3N8+H3N2; intervals killed, adjuvanted, parenteral) Canine leishmaniosis Three doses, 3 weeks apart Three doses, 3 weeks apart Annually Non-­Core. Prevention of (CanL; recombinant with the initial dose at canine leishmaniosis protein A2, parenteral) >4 months of age depends crucially on diligent ectoparasite control so as to minimise contact with the vectors. Vaccination can be regarded as a supplementary control measure, not a substitute for diligent ectoparasite control CanL [excreted-­secreted Three doses, 3 weeks apart Three doses, 3 weeks apart Annually proteins (LiESP) of L. with the initial dose at infantum, parenteral] >6 months of age CanL (recombinant Protein A single dose at >6 months A single dose Annually Q, parenteral) of age Canine herpesvirus-­1 (CHV-­ Not applicable. This vaccine Two doses during pregnancy Manufacturer This vaccine is intended to 1; subunit, parenteral) is intended for pregnant First dose – During oestrus recommends protect newborn puppies. bitches or 7 to 10 days after the repeating the two Infection (usually from the presumed date of mating injection protocol dam) can be fatal in young Second dose – 1 to 2 weeks during each puppies, 16 weeks Revaccination Comments and recommendations Vaccines not recommended for pet dogs Canine parvovirus-­2 (CPV; Not recommended for general use in pet dogs where MLV vaccines are available killed, parenteral) MLV vaccines against canine parvovirus-­2 are more potent and induce longer duration of immunity. Some MLV vaccines have been proven to be safe for use in pregnant bitches. Check the product leaflet to be sure. If safe MLV vaccines are unavailable in particular areas, use of inactivated vaccine is justified Canine coronavirus Not recommended (CCoV; killed and MLV, The evidence that CCoV is an important primary pathogen in adult dogs is weak. The diarrhoea associated with CCoV parenteral) infection in puppies is usually mild, and the infection usually occurs in young puppies, sometimes before they are first vaccinated. Co-­infection with canine parvovirus-­2 can be managed by protecting robustly against parvoviral infection. There is no evidence that the CCoV vaccines currently available would protect against mutant pathogenic forms of the virus (pantropic or more highly pathogenic strains) that emerge and are identified infrequently Giardia spp. vaccines Not recommended. There is insufficient scientific evidence to justify their use Giardia duodenalis infection is non-­life threatening, responds to therapy, and is rarely transmitted from puppies or dogs to humans. There is insufficient evidence that Giardia vaccines can prevent the shedding of Giardia oocysts. Vaccines do not prevent infection and vaccinated dogs can develop clinical signs of infection Microsporum canis Not recommended. There is insufficient scientific evidence to justify their use vaccines Even when the last puppy vaccine dose is administered at 16 weeks of age or slightly later, a small percentage of puppies may not respond adequately to vaccination because of persisting MDA (Friedrich & Truyen, 2000; Thibault et al., 2016). For this reason, the VGG recommends either serological testing at least 4 weeks after the last puppy vaccination (i.e. at or after 20 weeks of age if these guidelines are followed) or, alternatively, an additional vaccination at or shortly after 26 weeks of age. This recommendation, first made and explained in a previous iteration of these guidelines (Day et al., 2016), replaces an earlier recommendation for a “first annual booster” with core vaccines at 12 to 16 months of age. Vaccinating puppies at 26+ weeks of age rather than waiting until 52 weeks of age or later does not increase the number of core vaccine doses administered to the animal but will substantially reduce the period of susceptibility for those few that have not yet mounted an active immune response. The VGG’s previous recommendation (Day et al., 2016) was for this vaccination to be given at 26 to 52 weeks of age. In these latest guidelines, the revised recommendation is for this vaccination to be given at or shortly after 26 weeks of age. Puppies in which serological testing at 20+ weeks of age reveals protection against CPV, CDV and CAV do not need the 26+ week vaccination. This recommendation for earlier revaccination is certainly not mutually exclusive to, nor should it preclude, a first annual health check at approximately 1 year of age with administration of rabies vaccine (where needed) plus any non-­core vaccines deemed neces- sary. Understandably, many veterinarians are keen to re-­examine the dogs under their care as they reach or approach skeletal and behavioural maturity. Some licensed vaccines have datasheet recommendations for a 10-­or 12-­week finish to the puppy vaccination series. Small experimental studies (e.g. Bergman et al., 2006), have supported this recommendation. However, other experimental studies and field studies have produced contrary results and some of the supportive experimental evidence was compromised by the so-­called “pen effect” (Ellis, 2015). The “pen effect” describes a situation in which experimental puppies are group-­housed and have the opportunity to share mucosally shed vaccinal virus within each group. This would substantially and artificially increase their opportunities to become immunised, leading to potential over-­estimation of the benefits afforded by vaccination. The VGG therefore continues to recommend finishing no earlier than 16 weeks and preferably following that with serological testing or a 26+ week revaccination. Part of the rationale for “early finish” protocols was to permit early socialisation of puppies. The VGG strongly supports early socialisation as essential to healthy behavioural development and future well-­being of dogs (Korbelik et al., 2011). Early socialisation can be achieved while following these WSAVA vaccination guidelines. Research has shown that the risk to puppies partway through their initial vaccination series of developing CPV-­related disease by attending early socialisation classes is low (Stepita et al., 2013). The same is likely to be true for CDV and CAV. Dogs that have responded optimally to vaccination with MLV core vaccines maintain solid immunity for many years in the absence of repeated vaccinations (Bohm et al., 2004; Jensen et al., 2015; Mitchell et al., 2012; Mouzin et al., 2004a; Schultz, 2006; Schultz et al., 2010). Once puppies have mounted an active immune response, subsequent revaccination need be given no more often than triennially. If a core vaccine is given at 26+ weeks of age, then to synchronise core vaccinations with annual health checks, simply for client convenience, the next dose might be given at 3 years of age (rather than waiting until 3.5 years of age). It should be emphasised that inactivated core viral vaccines for dogs do not provide such long-­lasting protection as do MLV vac- cines. Recombinant core canine vaccines provide protection similar to MLV vaccines. A detailed comparison is beyond the scope of this document. 14 Journal of Small Animal Practice © 2024 WSAVA  17485827, 0, Downloaded from https://onlinelibrary.wiley.com/doi/10.1111/jsap.13718 by UNIVERSIDADE ESTADUAL PAULISTA, Wiley Online Library on [03/04/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Adult dogs with an unknown or incomplete vaccination history are frequently presented for vaccination. A single dose of MLV core vaccine will very likely be sufficient to induce immunity in pet dogs over 26 weeks of age and will provide long-­lasting protection. In high-­risk situations (e.g. outbreaks), it would be prudent to consider providing a second dose, 2 to 4 weeks later. In rabies endemic areas, rabies vaccines should also be administered. Most rabies vaccines are inactivated but are remarkably immunogenic. A single dose can immunise, in contrast to many other inactivated vaccines. A recommendation in some parts of the world is to give a first rabies vaccine dose at 12 weeks of age with a second dose one year later, although recommended dosing schedules for locally manufactured vaccines in some countries may differ from this and should be followed (Pimburage et al., 2017). Revaccination intervals for canine rabies vaccines are often mandated by law. Rabies vaccines usually carry a 1-­or 3-­year licensed DOI. Revaccination intervals should be based primarily on local regulations and, in the absence of these, on datasheet DOI claims. In countries where the legal requirement is at odds with the vaccine datasheet, the law must be followed. Locally manufactured rabies vaccines with a 1-­year DOI should not be assumed to be safe and effective for triennial use. Vet- erinarians should be mindful of the law, but where they have access to a product that has been shown to provide a minimum of 3 years of immunity, national veterinary associations might consider lobbying to have local regulations changed to match the current scientific evidence. Vaccines to protect against canine leptospirosis are now considered core in these guidelines if, in the regions where the dog lives or to which it travels, leptospirosis in dogs is prevalent, implicated serogroups are known and suitable vaccines are commercially available. This means that, according to these guidelines, vaccines to protect against canine leptospirosis will be designated as core in many but not all parts of the world. In a few parts of the world that have been studied carefully, for example South Aus- tralia, there is little to no evidence that canine leptospirosis occurs (Zwijnenberg et al., 2008). Alas, in many parts of the world, it remains undetermined which serogroups would need to be included in vaccines for local use to protect dogs against leptospirosis. A vaccine cannot be designated as “core” if it is uncertain which vaccine should be given. Currently, this remains true despite some interesting, paradigm-­challenging French work that suggests there may be a degree of cross protection among members of different serogroups (André-­Fontaine & Triger, 2018). The commercial development of “pan-­protective” vaccines (Chaurasia et al., 2022), which may be able to protect dogs against leptospirosis caused by a large majority of the known pathogenic variants, should be eagerly awaited and, if such vaccines are successfully developed, will substantially extend the regions of the world in which leptospirosis vaccines can be considered “core.” Globally, there are currently monovalent, bivalent, trivalent and quadrivalent vaccines to protect dogs against canine lep- tospirosis. These variously contain serovars belonging to serogroups Icterohaemorrhagiae, Canicola, Grippotyphosa, Pomona and Australis (Francey et al., 2020; Klaasen et al., 2012, 2014; Schuller et al., 2015; Sykes et al., 2023; Wilson et al., 2013). Quadrivalent vaccines provide broader protection. In general, these vaccines provoke strong but transient seroconversion (Mar- tin et al., 2014). Immunity (protection against virulent challenge) lasts much longer than the period of seropositivity (up to 15 months; Grosenbaugh & Pardo, 2018). Two doses of inactivated vaccines, such as those that protect against leptospirosis, are required to immunise. Non-­core vaccines for pet dogs Summary information about non-­core vaccines for dogs is provided in Table 1. The most widely used non-­core vaccines for dogs are those against Bordetella bronchiseptica and canine parainfluenza virus (CPiV). Other non-­core vaccines with more restricted geographical availability include those against Borrelia burgdorferi, canine influenza virus (CIV) and Leishmania infantum. There is also a subunit vaccine against Canine Herpesvirus-­1, specifically for use in bitches during pregnancy. This vaccine has been shown to induce an increase in maternal serum neutralising antibodies in seronegative bitches. This antibody is passively transferred in colostrum and was shown to protect puppies during early life (16 weeks Revaccination Comments and recommendations Core vaccines for pet cats FPV+FCV+FHV: parenteral, live attenuated Feline panleukopenia Start no earlier than Two doses 2 to Consider revaccinating at Core worldwide virus (FPV)+feline 6 weeks of age and 4 weeks apart about 6 months of age, The live attenuated FPV component herpesvirus-­1 revaccinate every 3 to are generally rather than waiting until the provides rapid, potent, long-­lasting (FHV)+feline 4 weeks until 16 weeks recommended cat is 12 to 16 months of protection calicivirus (FCV) of age although a single age. This will narrow the More frequent revaccination (up to In especially high-­risk dose can be window of susceptibility for annually) should be considered for situations continue until expected to protect any kittens that failed to cats at higher risk. For example, 20 weeks of age and many cats mount an active immune cats that go into boarding catteries consider vaccinating every response earlier or visit other high-­stress, high-­ 2 to 3 weeks Thereafter, revaccinate “low risk environments should be risk” cats at 3 years of revaccinated 1 to 2 weeks before age and then no more exposure frequently than every Pregnant queens and kittens 3 years 16 weeks Revaccination Comments and recommendations Rabies: recombinant and inactivated Rabies Follow local regulations as Follow local Revaccination as required Core in areas where the disease is (canarypoxvirus-­ a priority. If there are no regulations as a by local regulations or as endemic vectored regulations, follow the priority. If there per licensed duration of recombinant, product leaflet are no regulations, immunity (DOI)/product non-­adjuvanted, follow the product leaflet parenteral) leaflet Rabies (1-­and 3-­year Follow local regulations as Follow local Revaccination as required Core in areas where the disease is DOI inactivated, a priority. If there are no regulations as a by local regulations or as endemic adjuvanted regulations, follow the priority. If there per licensed duration of products, product leaflet are no regulations, immunity (DOI)/product parenteral) follow the product leaflet leaflet FeLV: recombinant and inactivated FeLV (recombinant, Start as early as 8 weeks Two doses, 3 to Revaccinate 1 year following FeLV vaccines are core for young adjuvanted, of age 4 weeks apart the last dose of the initial cats 16 weeks Revaccination Comments and recommendations Chlamydia felis (avirulent Administer the initial dose Administer two doses, Annual boosters are Vaccination is most appropriately live, non-­adjuvanted, as early as 9 weeks of 2 to 4 weeks apart indicated for cats at used as part of a control parenteral) age; a second dose is sustained risk of exposure regime for animals in multi-­cat Chlamydia felis (killed, administered 2 to 4 weeks environments where infections adjuvanted, parenteral) later associated with clinical disease have been confirmed. Inadvertent conjunctival inoculation of live vaccine has been reported to cause clinical illness Bordetella bronchiseptica Administer a single dose Administer a single Annual boosters are Not routinely used in pet cats (avirulent live, non-­ intranasally as early as dose intranasally indicated for cats at Consider use in pet cats that are adjuvanted, intranasal) 4 weeks of age sustained risk of exposure kept in unusually large colonies Vaccines not recommended for pet cats Feline infectious There is insufficient scientific evidence to justify a broad recommendation for the use of this vaccine. This vaccine is labelled peritonitis (FIP; live for use in kittens from 16 weeks of age. It contains a live, temperature-­sensitive virus that can replicate in the nose, but attenuated, non-­ not at higher core body temperatures. This is important for the safety of the vaccine. According to the limited studies adjuvanted, intranasal) available, only cats known to be feline coronavirus antibody-­negative at the time of vaccination are likely to develop some level of protection. It is uncommon for cats to be coronavirus antibody negative at 16 weeks of age or older In addition, this vaccine contains a virus strain that differs from clinically important strains found in some well-­studied parts of the world Giardia spp. vaccines There is insufficient scientific evidence to justify use Microsporum canis There is insufficient scientific evidence to justify use vaccines In regions where rabies is endemic, the VGG recommends that all cats should be vaccinated against rabies for the protection of both pets and humans, even if legislation does not require this for cats. Licensed rabies vaccines for cats generally have a 1-­or 3-­year DOI claim. Revaccination frequency should be based primarily on local regulations and, if these are absent, on datasheet DOI claims. Whereas all three globally relevant canine core vaccine components (CPV, CDV and CAV) provide strong and long-­lasting pro- tection when used properly (Schultz et al., 2010), the protection afforded by the core FCV and FHV vaccine components will not match that provided by FPV vaccines. FCV vaccines produce a degree of cross-­protective immunity against multiple strains of FCV. However, it is still possible for infection and disease to occur in fully vaccinated adult animals (Pedersen et al., 2000; Schorr-­Evans et al., 2003). There is no FHV vaccine that can prevent infection. Infection often leads to the virus becoming latent in neural tissue with the possibility of reactivation during periods of stress (Maes, 2012; Richter et al., 2009). Reactivated virus may cause clinical signs in vaccinated animals, or the virus may be shed to susceptible animals and cause disease in them. Cats that have responded to vaccination with MLV core vaccines maintain solid immunity against FPV for many years in the absence of repeated vaccination. Immunity against FCV and FHV is only partial (Jas et al., 2015) and may be weakened by the stress of boarding (Gourkow et al., 2014; Gourkow & Phillips, 2015). The VGG recommendation for adult “low risk” cats (solitary, indoor animals that do not visit boarding catteries) is for revaccination with MLV core vaccines at intervals of 3 years or longer. For “higher-­ risk” cats more frequent revaccination to protect against FCV and FHV (up to annually) may be warranted. This includes cats that regularly visit boarding catteries or have other contact with potentially infected cats. In cats that board, a FCV/FHV vaccine can be given 1 to 2 weeks before the main annual visit to the boarding cattery (Gaskell et al., 2007; Stone et al., 2020). In some countries, bivalent FCV/FHV vaccines are commercially available, alongside the more typical trivalent FPV/FCV/FHV vaccines. These bivalent vaccines enable veterinarians to vaccinate higher risk cats against FCV/FHV annually and against FPV triennially, or less frequently. Intranasal MLV FPV/FHV/FCV and FHV/FCV vaccines are available in some countries (Lappin, Sebring, et al., 2006b; Reagan et al., 2014). These recommendations about revaccination frequency apply to MLV vaccines. Inactivated FPV vaccines typically do not provide such long-­lasting protection as do MLV FPV vaccines. Inactivated FCV and FHV vaccines have been shown experimentally to pro- vide long-­lasting, partial protection (Scott & Geissinger, 1997, 1999). However, the environment used in this study was extremely stable and most likely experienced as “low stress” by the cats. It was unlike a typical boarding cattery situation. In this latest iteration of these guidelines, the VGG has decided to designate FeLV vaccines as core in parts of the world where FeLV-­related diseases are known to occur. In these parts of the world, this designation applies to young cats (