Michael J. Day, BSc, BVMS (Hons), PhD, DSc, DlECVP, FASM, FRCPath, FRCVS
Guidelines for feline vaccination are produced by the American Association of Feline Practitioners,1 the European Advisory Board on Cat Diseases,2 and the WSAVA Vaccination Guidelines Grou. The fundamental basis of all of these guidelines is to improve the safety of feline vaccination by reducing the frequency of vaccination of individual animals, whilst maintaining population immunity (herd immunity). Guidelines were born out of discussions within the veterinary profession of vaccine-associated adverse events (VAAEs) in dogs and cats. The most significant companion animal VAAE is the feline injection site sarcoma (FISS). The most recent estimate of the prevalence of this lesion is in the order of 1/5000 to 1/12500 feline vaccinations in the UK.4 In contrast, the prevalence of VAAEs in cats up to 30 days post-vaccination is reported as 52/10000 cats vaccinated, with just over 50% of these reactions taking the form of mild, transient lethargy and pyrexia within the days following vaccination.5
In recent years, vaccination guidelines have aligned much more closely with the recommendations given by manufacturers on data sheets and consequently with recommendations given by licensing authorities. There remain some inconsistencies and so practitioners should be mindful that use of vaccines in accordance with guidelines might sometimes require informed client consent. There are also significant global differences. Whilst guidelines are widely adopted in North America and Western Europe, there are many areas of the world in which vaccination practice has not yet caught up with global trends. The use of vaccines in accordance with guidelines requires understanding of several key principles as outlined below.
Core Versus Non-Core Vaccines
Core vaccines are those that all animals should receive to protect against diseases of global significance. 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), Chlamydophila felis and Bordetella bronchiseptica. Vaccines against feline immunodeficiency virus (FIV) and feline infectious peritonitis (FIP) are currently not recommended for use.
Selection of Non-Core Vaccines
One factor that would facilitate rational selection of non-core vaccines would be robust local surveillance data as to the prevalence of specific infectious diseases in the practice area. There are the beginnings of such practice-based surveillance programmes in several countries now, and practitioners should be encouraged to participate in these programmes. 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 multi-cat household). Vaccination is now an example of 'individualised medicine' and is no longer as simple as having a practice 'vaccination protocol'.
Minimize Adjuvanted Vaccines
Although it is now recognized that 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.6
An in-practice serological test kit is now available for detection of serum antibody to FPV, FCV and FHV (Feline VacciCheck®, Biogal Laboratories). The kit has been validated against 'gold standard' laboratory methodology and used in several independent studies. The most recent of these evaluates the test for FPV antibody, showing specificity of 81–89% and sensitivity of 78–87% and recommends the test for practice use.7 There is good correlation between FPV seropositivity and protection from disease (not necessarily for FCV and FHV), so this test may be used to determine whether an adult cat requires revaccination against FPV. Many practices are now offering serological testing as an alternative to revaccination for the FPV component of vaccines.
Use Maximum Duration of Immunity Products
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 (see client consent above). For the cat, there are field serological data that show persistent seropositivity for 4 or more years post-core MLV vaccination8 and one experimental challenge study that shows immunity for a minimum period of 7.5 years following vaccination of kittens with killed adjuvanted trivalent vaccine.9
The Health Check Concept
The WSAVA promotes the delivery of vaccination within the annual health check, which assesses holistically the health and wellbeing of the individual pet. Vaccination is just one element of this annual consultation during which consideration may be given as to whether any vaccine will be administered that year (or a serological test performed) and which components might be delivered. Emphasis is removed from the 'vaccine booster' as the primary reason for an annual practice visit.
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.10 Current advice would be that the third kitten vaccine be given at the 16th week end of the range, but it is likely that this recommendation might be extended in the future. 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.
Vaccination of Adult Cats
WSAVA guidelines 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. Where non-core FeLV vaccination is selected, the VGG recommends that adult cats are revaccinated no more frequently than every 3 years.
A recent U.S. study has shown that most cats entering a shelter were seronegative for FPV, FCV and FHV.11 This supports current advice that cats should be given core vaccine as soon as possible before or after entry to the shelter. Cats entering boarding catteries should also have current core vaccination and consideration might be given to use of non-core respiratory tract vaccine in these animals.
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. Dean RS, Pfeiffer DU, Adams VJ. The incidence of feline injection site sarcomas in the United Kingdom. BMC Vet Res. 2013;9:17.
5. Moore GE, et al. Adverse events after vaccine administration in cats: 2560 cases (2002–2005). J Am Vet Med Assoc. 2007;231:94–100.
6. Hendricks CG, Levy JK, Tucker SJ, et al. Tail vaccination in cats: a pilot study. J Feline Med Surg. 2014;16:275–280.
7. Mende K, Stuetzer B, Truyen U, et al. Evaluation of an in-house dot enzyme-linked immunosorbent assay to detect antibodies against feline panleukopenia virus. J Feline Med Surg. 2014. Epub ahead of print. doi:10.1177/1098612X14520812.
8. 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.
9. Scott FW, Geissinger CM. Long-term immunity in cats vaccinated with an inactivated trivalent vaccine. Am J Vet Res. 1999;60:652–658.
10. 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.
11. DiGangi BA, Levy JK, Griffin B, et al. Prevalence of serum antibody titers against feline panleukopenia virus, feline herpesvirus 1, and feline calicivirus in cats entering a Florida animal shelter. J Am Vet Med Assoc. 2012;241:1320–1325.