The aim of this presentation is to review the current global guidelines for feline vaccination and to consider how they might apply to veterinary practice in Asia as considered by the WSAVA Vaccination Guidelines Group (VGG) during their 2-year project in Asia.
Global Feline Vaccination Guidelines
Guidelines for feline vaccination are produced by the American Association of Feline Practitioners1, the European Advisory Board on Cat Diseases2 and the WSAVA VGG3. The fundamental principle of these guidelines, as encapsulated by the VGG, is that 'we should aim to vaccinate every animal with core vaccines and to vaccinate each individual less frequently by only giving non-core vaccines that are necessary for that animal'.
The WSAVA guidelines suggest that we should aim to vaccinate more animals. This relates to the phenomenon of 'herd immunity'. Herd immunity suggests that where at least 75% of a herd of animals is vaccinated, it is difficult for an infectious disease outbreak to occur. The 'herd' for a small animal practitioner is the population of dogs and cats living within his or her practice area - and our aim should be to have as many of these animals vaccinated as possible, in order to reduce the chances of disease outbreak in the herd. This is particularly important in the context of canine rabies. Where a mass vaccination campaign results in at least 70% of the dog population receiving vaccine, there is marked impact on the prevalence of canine and human rabies.
In order to apply the principles of vaccination guidelines, it is firstly necessary to understand the definitions of 'core' and 'non-core' vaccines. Core vaccines are those that all animals should receive to protect them against diseases of global significance or where legislation may dictate (i.e., canine rabies). The use of non-core vaccines is dictated by geographical location, lifestyle and exposure risk. Some vaccines are not recommended because there is little scientific justification for their use.
Core vaccines for the cat are those that protect against feline parvovirus (FPV), feline calicivirus (FCV) and feline herpesvirus-1 (FHV). In rabies-endemic countries, rabies vaccination is also considered core for cats, even if not dictated by legislation. Non-core vaccines are those for which use is dictated by geographical location, lifestyle and exposure risk. Non-core vaccines for the cat are those that protect against feline leukaemia virus (FeLV), Chlamydia felis and Bordetella bronchiseptica. Vaccines against feline immunodeficiency virus (FIV) and feline infectious peritonitis (FIP) are currently not recommended for use.
WSAVA guidelines provide generic advice to practitioners, but it is impossible to ensure that the guidelines are tailored to best fit the local situation in each of the 78 WSAVA member countries. The VGG encourages national associations to adapt and modify the guidelines for local use where appropriate. This process might involve altering the classification of a vaccine. For example, in the UK, FeLV vaccine is often considered core for the cat and administered routinely to kittens.
Core Vaccination of Kittens
Core vaccination of kittens (FPV, FCV, FHV) begins at 8–9 weeks of age, with a second vaccine given 3–4 weeks later and a third vaccine given between 14–16 weeks of age. The 12-month booster is also an integral part of the kitten programme. Increasing evidence suggests that maternally derived antibody (MDA) may persist for up to 20 weeks in some kittens.4 Current advice would be that the third kitten vaccine be given at 16 weeks of age or older. Where rabies is endemic, kittens should receive 1 dose of vaccine at 12 weeks of age, but the VGG suggests that in a high-risk situation, a second dose of vaccine may be given 2–4 weeks later.
Core Vaccination of Adult Cats
Some FPV vaccines now carry a licensed duration of immunity (DOI) of 3 years; however, vaccines against FCV, FHV and non-core products all have a 1-year DOI. Rabies vaccines (including one non-adjuvanted product) also have a 3-year DOI in many countries. Selecting products with extended DOI reduces the frequency of administration of that component. Guidelines may still advise triennial revaccination with products carrying a 1-year licensed DOI. For the cat, there are field serological data that show persistent seropositivity for 4 or more years post core MLV vaccination5 and one experimental challenge study that shows immunity for a minimum period of 7.5 years following vaccination of kittens with killed adjuvanted trivalent vaccine6.
WSAVA guidelines therefore recommend that adult cats receive MLV core vaccines (FPV, FCV and FHV) no more frequently than every 3 years. The VGG also recognizes that based on individual risk assessment, some practitioners may wish to deliver annual FCV/FHV vaccination. Using product ranges that split out FPV from the respiratory components, such a protocol is entirely feasible. Rabies vaccination of adult cats may now be performed triennially using products with an appropriate licensed duration of immunity (DOI) of 3 years.
Non-core Vaccination
Non-core vaccines should be selected for the individual cat based on assessment of that particular animal's risk of exposure to the disease and assessment of the benefits of vaccination to that pet versus the risk of adverse reaction. Decision-making for non-core vaccines would be facilitated by having available good-quality data and disease distribution maps related to small animal infectious diseases. Unfortunately, with the exception of rabies in the USA and Europe, such distribution maps are not widely available. Some national schemes have been developed by industry or academic groups which allow practitioners to input cases of particular infectious diseases into a database that presents the information as disease distribution maps. Additionally, consideration must be given to the vaccine requirements of the individual animal, based on assessment of their lifestyle (e.g., indoor versus outdoor, travel and boarding frequency and location, solitary or multicat household). Vaccination is now an example of 'individualised medicine' and is no longer as simple as having a practice 'vaccination protocol'.
For example, where non-core FeLV vaccination is selected for kittens, an initial dose is given at 8 weeks of age, with a second 3–4 weeks later, followed by a 12-month booster. The VGG recommends that adult cats are revaccinated against FeLV no more frequently than every 3 years.
Minimize Adjuvanted Vaccines
Although it is now recognized that the feline injection site sarcoma (FISS) may be associated with a wide range of injectable or topical products, it is clear that adjuvanted FeLV and rabies vaccines are one such risk factor in the transformation of local chronic inflammation to neoplasia. A number of strategies have been proposed to minimise the surgical consequences of any FISS that might develop in a cat. The WSAVA currently advises vaccination into the skin of the lateral abdomen, while the AAFP continues to advise vaccination into the distal hindlimb for rabies and FeLV. A recent study has shown the efficacy of vaccination for FPV when vaccine is administered into the distal tail, although there remain concerns about this procedure.7
The Annual Health Check
All aspects of vaccination should fall under an annual health check programme that reduces the emphasis on vaccination as a reason for visiting the practice and considers holistically the overall health and wellbeing of the pet. A discussion about which vaccines (or serological tests) might be offered in any one year is just one part of the annual health check. The importance of vaccination can be reinforced by using the VGG fact sheets. Vaccination (or serology) should be appropriately invoiced so emphasis is placed on the professional consultation.
Aspirational Feline Vaccination Guidelines for Asia
It should be the aspiration of practitioners in Asia to vaccinate cats in accordance with the global guidelines as practiced in many other regions and countries and described above and in the VGG recommendations for Asia.8
Key steps towards adopting WSAVA guidelines would involve:
Understanding herd immunity: it is more important to vaccinate more animals than to increase vaccination frequency for the individual
Understanding the core versus non-core concept
Implementing the fundamental principles of WSAVA guidelines when using international quality-assured MLV core vaccines
Using non-core vaccines based on risk
Pragmatic Feline Vaccination Guidelines for Asia
There are particular challenges in adopting the WSAVA guidelines in countries where reduced component vaccine products (e.g., a vaccine containing only FPV, FCV and FHV-1 rather than these being part of a multicomponent combination) are not yet available. Additionally, there are some Asian countries where no feline vaccine products are marketed. The veterinary profession should lobby industry and regulators to make such products more widely available. Additionally, practitioners should be educated in the global changes, particularly the core versus non-core concept, and the move to 3- to 4-year adult revaccination with international quality-assured MLV vaccines, the administration of a final puppy/kitten vaccine at or above 16 weeks, and the concept of vaccination as individual medicine.
Asian practitioners might already consider adopting the following approaches:
Select international quality-assured core vaccines with known FPV 3-year licensed DOI in other countries and discuss with owners the fact that these vaccines might safely and effectively be used triennially with informed client consent. This practice is no different to the global situation 20 years ago, when core vaccines with a 1-year licensed DOI were first given triennially with informed client consent.
Select vaccines that include the minimum number of antigenic components to use as 'core' in the practice.
Advise administration of core vaccine to kittens in accordance with current global guidelines.
Where one vaccine is used to dilute another and the 'diluent vaccine' is non-core and not required for that animal, use an alternative diluent.
Carefully consider the use of non-core vaccines and whether these are required for the individual animal.
Where an international quality-assured rabies vaccine is available that has known 3-year licensed DOI in other countries, lobby the authorities to move away from requiring annual revaccination for owned, veterinarian-visiting pet cats and lobby industry to provide regulatory data to support relicensing of these products for national markets with a 3-year DOI.
National small animal veterinary associations should lead in implementing these changes and provide advice to their membership that is consistent with the principles described above.
References
1. Scherk MA, Ford RB, Gaskell RM, et al. 2013 AAFP Feline Vaccination Advisory Panel report. J Feline Med Surg. 2013;15:785–808.
2. Hosie MJ, Addie D, Belak S, et al. Matrix vaccination guidelines: ABCD recommendations for indoor/outdoor cats, rescue shelter cats and breeding catteries. J Feline Med Surg. 2013;15:540–544.
3. Day MJ, Horzinek M, Schultz RD. Guidelines for the vaccination of dogs and cats. J Small Anim Pract. 2010;51:338–356.
4. Jakel V, Cussler K, Hanschmann KM, et al. Vaccination against feline panleukopenia: implications from a field study in kittens. BMC Vet Res. 2012;8:62.
5. Mouzin DE, Lorenzen MJ, Haworth JD, et al. Duration of serologic response to three viral antigens in cats. J Am Vet Med Assoc. 2004;224:61–66.
6. Scott FW, Geissinger CM. Long-term immunity in cats vaccinated with an inactivated trivalent vaccine. Am J Vet Res. 1999;60:652–658.
7. Hendricks CG, Levy JK, Tucker SJ, et al. Tail vaccination in cats: a pilot study. J Feline Med Surg. 2014;16:275–280.
8. Day MJ, Karkare U, Schultz RD, Squires R, Tsujimoto H. Recommendations on vaccination for Asian small animal practitioners: a report of the WSAVA Vaccination Guidelines Group. J Small Anim Pract. In press.