2013 AAFP Feline Vaccination Margie A Scherk et al.
The AAFP produced the first organization driven vaccination guidelines in 1998. These
were updated in 2000 and again in 2006.1 Each version has offered a comprehensive review
of the literature and has provided recom - mendations for vaccine protocols based on
known science along with some extrapolation between studies and between species when
feline studies were not available. This Report has used the same criteria.
The practicing veterinarian is in the best position to determine how to put these Guidelines into practice for an individual patient. The veterinarian should undertake a clinical risk/benefit assessment for each animal and discuss recommended vaccination schedules with the owner so that they can
make an informed choice. The assessment should include discussion on the likelihood of exposure, the health and lifestyle of the animal, and the risks related to vaccination.
The Advisory Panel recognizes that situations differ in different countries, and that every country will have slightly different issues and priorities; thus these Guidelines
will not necessarily be applicable to every country and the practitioner must interpret accordingly.
The three international panels that have produced feline vaccination guidelines (AAFP, World Small Animal Veterinary Association and European Advisory Board on Cat Diseases) recommend that an annual health examination be performed irrespective of whether vaccines are administered.
While the optimal frequency of health examinations for cats is unknown, it is generally accepted that healthy adult cats should be examined at least once a year. In the past, annual veterinary visits were structured around vaccinations as the primary focus. With the increasing body of knowledge about
duration of immunity (DOI) from vaccinations, their potential adverse effects, and the increased awareness of pet owners about these issues, it is clear that vaccination no longer justifies the need for annual visits.
Practitioners are encouraged to help cat owners understand the value of regular health care and that it ideally should be proactive rather than reactive. A useful approach is for health care to be tailored to the various feline life stages, which improves early recognition of potential health-related issues
and can facilitate treatment.2 A Pet Owner Guide, discussing the risks and benefits of vaccination, is included as Appendix 2 (pages 807 and 808).
Vaccination principles
Vaccination plays an important role in the control of infectious diseases, both for an individual as well as for the cat population (ie, herd health). Some vaccine antigens are also used to lessen the potential for zoonotic spread of disease (eg, rabies). The benefits of routine and widespread vaccination are clear: the incidence of serious disease caused by highly pathogenic organisms, such as feline parvo - virus (panleukopenia), can be reduced in populations in which widespread vaccination is practised. However, the level of protection conferred by a particular vaccine in an individual patient varies. The quality of vaccine induced immunity in any patient is influenced by a complex interaction of factors unique to the individual patient, the patient’s environment, and the nature of the vaccine and pathogen. Precisely predicting either the outcome of vaccination or subsequent exposure to a pathogen is difficult (or impossible) and, therefore, vaccination should never be offered as a guarantee of protection.
The risk of infection and subsequent development of disease varies with a number of factors including the age and health of the cat, magnitude of exposure to the infectious agent, the pathogenicity of individual agents, the geographic prevalence of infection and the vaccination history of the cat. Some of the factors that negatively affect an individual animal’s ability to respond to vaccination include interference from maternally derived antibodies (MDA), congenital or acquired immunodeficiency, concurrent disease or infection, inadequate nutrition, immunosuppressive
medications, chronic stress and an aging immune response. Additionally, some vaccinal agents (eg, FPV) will induce a much stronger protective immune response than others (eg, feline herpesvirus [FHV-1]). As vaccine-afforded protection against both infection and disease is thus variable and not absolute, exposure to infected animals and infectious agents should be minimized, even after vaccination.
Kittens are generally more susceptible to infections than adult cats are and typically develop more severe disease (Figure 1). Thus, they represent a principal primary target population for vaccination. As part of a routine health care program,the vaccination needs of all cats, including adults, should be assessed at least once a year, in conjunction with a comprehensive physical examination and consultation, modifying vaccination recommendations as necessary on the basis of altered risk/benefit ratio.
Vaccination is a medical procedure, and the decision to vaccinate, even with core vaccines
(see box above), should be based on a risk/benefit assessment for each cat and for each vaccine antigen. Vaccination may indeed be beneficial, but it is not innocuous, and the benefit of vaccinating an animal (eg, the induction of clinically meaningful immunity) must be balanced against the risk of adverse events, likelihood of exposure and severity of disease. Where practical, every effort should
be made to ensure that cats are healthy prior to vaccination; however, concurrent illness should not necessarily preclude vaccination.
The overall objectives of vaccination are shown on the right.
General information on types of feline vaccines
Vaccines, including different products licensed to protect against the same pathogen, are not necessarily alike. Different vaccine technologies may directly influence efficacy, safety, DOI and route of administration of individual products. Awareness of fundamental differences is necessary.
The following terminology is used throughout these Guidelines to describe types of vaccines: inactivated (killed), modified-live (attenuated) and recombinant. The attributes of each vaccine type are summarized in Table 1.
Characteristics of vaccine types have been reviewed as recently as 2011.3All veterinary vaccines,
prior to licensing, are subjected to testing for efficacy, safety, potency and purity. Testing methods may vary among different manufacturers and licensing authorities. While all licensed vaccines need to meet minimum efficacy standards, the level of protection induced can vary depending on many factors, including the method used to manufacture the product. For further information on licensing, readers should refer to the 2006 Guidelines (see box on page 786) and to individual licensing authorities (United States Department of Agriculture [USDA]; Canadian Food Inspection Agency
[CFIA]; Veterinary Medicines Directorate [VMD], Department for Environment, Food, and Rural Affairs [DEFRA], UK; European Medicines Agency [EMA], EU).
The principal differences between inactivated, modified-live and recombinant vaccines are discussed below. < Inactivated vaccines Vaccinal pathogens can be completely inactivated (ie, killed) by
various means, eliminating risk of replication post-inoculation or ‘reversion to virulence’.
For these reasons, inactivated vaccines have historically been regarded as the safest vaccines. However, the inclusion of a variety of extraneous chemicals (stabilizers, preservatives), antibiotics, adjuvants and excipient proteins has been implicated as a cause of both acute and delayed adverse
reactions in cats.4< Modified-live vaccines For some agents,intact pathogens can be modified so that they retain the ability to replicate in the host and provoke an immune response, but not cause
clinical disease. Altered pathogenicity effectively induces subclinical infection and can result in a more rapid onset of immunity for some vaccine antigens than with comparable inactivated vaccines.5,6 All bacterial and viral vaccines licensed for mucosal (intranasal) administration are
modified-live, as are a number of injectable vaccines. < Recombinant vaccines Discrete genetic
sequences can be isolated from a pathogenic virus or bacterium that encode immunogenic proteins. These sequences can either be recombined with the DNA of a live,non-pathogenic virus, which can then be administered as a vaccine (vectored vaccine), or they may be inserted in bacterial plasmids
to enable in vitro production of antigens that can be harvested and purified for incorporation into a vaccine (ie, subunit vaccine). Examples of both types of vaccines are licensed for use in veterinary medicine.
Risk/benefit assessment
In assessing the risk for an individual cat, information about the cat, the environment and infectious agents to which the cat will be realistically exposed needs to be considered Specifically, questions need to be asked that address the cat’s lifestyle as well as the lifestyle of any other cats in the same household. Queries should also be posed regarding other sources of exposure, such as excursions
outside the home, boarding and travel.
Patient
Age is an important element in assessing an individual’s risk profile. Most infectious diseases are more prevalent in kittens, and kittens less than 6 months old are generally more susceptible to infection and disease than adult cats are. Kittens, therefore, represent a principal primary target population for vaccination.
MDA provide important protection for the kitten, but may also interfere with, or neutralize, vaccines. As the level of MDA varies among individuals, the age at which a kitten may be able to respond to vaccination will also vary, and in some cases may be 16 weeks or older. While information is available on the variability of MDA as pertains to FHV-1, FCV and FPV, limited data is available for other antigens; thus the role of MDA in interference with vaccination against rabies, FeLV or other
pathogens is unknown. Stopping a vaccination course too early (when MDA are stillinterfering) is thought to be the single most common cause of vaccination failure in kittens.
Patient’s environment
Population density and opportunity for exposure to other cats (eg, whether the cat is freeroaming
or has access to the outdoors) are among the most critical issues affecting risk of exposure to an infectious agent. Cats and kittens living in multiple-cat households and environments
(eg, boarding, breeding, foster or shelter facilities) are likely to have a substantially higher risk of infection than are cats living indoors in one- or two-cat households. Furthermore, the introduction of new cats into a household poses a potential risk – not only to the cat entering the household, but also to the whole group because of possible exposure to new infectious agents.
The immunosuppressive effects of stress inherent in the change of social demographics may also result in recrudescence and an increased susceptibility to infection and disease. Conversely, cats that are naturally exposed to infectious agents after vaccination may have an opportunity for ‘natural boosting of immunity’ that may not be afforded to cats kept alone.
Indoor cats generally have a low risk of exposure to infectious agents, particularly where the agent in question is only transmitted by direct contact among cats. However, they may also be exposed to infection from other cats in the household (ie, subclinically infected or carrier cats), or by indirect transmission of pathogens brought in from outside on owners’ clothing, shoes, etc. In theory, strictly indoor cats may be more susceptible to developing panleukopenia because they do not receive
boosting through the possibility of natural exposure. It is important to ask owners about other exposure that indoor cats may have, such as supervised visits out of doors (eg, on harness/leash, in the garden, etc), visiting other cats in an apartment building, balconies or roof gardens, visiting cats that belong to other family members, and staying in boarding facilities. Fostering shelter cats alters the riskfor the resident cats, both through potential direct exposure to infectious agents as well as
through stress-induced immunosuppression. Trap–neuter–return (TNR) and other special situations are discussed on pages 791–794.
Geographic distribution of infectious agents may result in substantially different risks of exposure for cats living in different areas (eg, rabies). Questions regarding future travel should be included in determining the risk of exposure to specific infectious agents. Periodic housing in boarding facilities, shelters or breeding facilities or other multiple-cat households also places cats at increased risk of exposure to a variety of infectious agents, although the risk will vary substantially between different situations.
Infectious agent
Independent agent-associated variables, such as virulence, strain variation and mutation, challenge dose and stability in the environment, influence the outcome of infection. These are difficult to assess objectively.
Recommendations for vaccination of household pet cats
Developing universal guidelines for vaccinationç of household pet cats is complicated by the lack of a clear definition of what is, and what is not, a ‘pet cat’. What follows are reasonable recommendations, based on scientific evidence and expert advice, applicable to most cats presented to private practitioners. Differences in cat population density, introduction of new cats, and
exposure risk are dynamic variables that the veterinarian must take into consideration when recommending any vaccine for any cat. It is advised that veterinarians reassess risk factors for exposure to infectious disease at each visit (at least once a year), as changes in factors such as the health of the animal or its lifestyle may dictate changes to vaccination
needs.
Table 2 summarizes vaccination recommendations for household pet cats.
Additional considerations when vaccinating household pet cats
Because vaccination requirements and risk of exposure to infectious agents vary among household pet cats, individual vaccination protocols will vary. The following recommendations address some alternative situations and offer insights on vaccination of pet cats using non-core vaccines.
< Vaccination of pet cats in indoor/outdoor households Cats housed exclusively indoors generally do not require vaccination beyond the aforementioned vaccines (ie, FPV, FHV-1, FCV ± FeLV, rabies). However, in multiple-cat households where some cats are housed exclusively indoors, yet other cats are permitted outside unmonitored, the entire household may be at risk of exposure to additional agents. Veterinarians should consider recommending vaccination of the entire household for selected diseases (eg, FeLV ± rabies) if exposure risk is deemed significant. Pet cats that spend most (or all) of their lives outdoors are at greater risk of exposure to most infectious diseases compared with predominantly indoor pet cats (Figure 2).
Offsetting this is the natural boosting of immunity they may receive if they are exposed to infectious agents. Among outdoor adult cats, exposure risk for rabies, FeLV and FIV is generally higher than for indoor cats. In addition to the conventional vaccines recommended in Table 2, FIV vaccination
could be considered for outdoor cats. (See accompanying Disease Information Fact Sheet on FIV – details on page 799.) < Vaccination of pet cats entering boarding facilities Although, in general, healthy adult cats only require boosters to FPV, FHV-1, FCV vaccines every 3 years, an additional booster 7–10 days prior to boarding may be warranted (and may be required by some catteries), particularly if the cat has not been vaccinated in the previous year. Boarding may be stressful for a cat and also, depending on the cattery and the situation at the time, may lead to exposure to infectious agents. However, disease control measures vary between facilities, with many providing
individual housing, sneeze barriers and good hygiene, whereas others permit co-mingling of cats, which will clearly facilitate disease transmission. In the event that kittens must enter a boarding facility, it is recommended that they should have received at least two doses of FPV, FHV-1, FCV vaccine, with the last dose 7–10 days prior to entry. In addition, it is strongly recommended that kittens be isolated from the general population of adult cats at all times while boarding.
< Vaccination during pregnancy and lactation Vaccination of pregnant or lactating cats is generally not recommended. Whenever possible, queens should be vaccinated before breeding. Vaccines are not evaluated for use in pregnant queens unless specifically stated on the label. However, the benefits of vaccination may outweigh the risks in endemic disease situations. Modified-live FPV vaccines should not be administered to pregnant queens as this has been associated with cerebellar
hypoplasia in the kittens.19 (For a more omprehensive discussion, see
‘Recommendations for vaccination of cats housed in breeding catteries’, page 793.)
< Overdue for vaccination If the cat has been vaccinated previously and is overdue
for revaccination (irrespective of the interval), generally a single vaccination is all that is
required. If prior vaccination status is unknown,
the cat should be treated as unvaccinated.
< Bordetella bronchiseptica, Chlamydophila felis, FIP and FIV vaccination For information on the use of these vaccines, see accompanying Disease Information Fact Sheets (details on page 799).
< Dermatophytosis vaccination At the time of writing, a monovalent (Microsporum canis) and
a multivalent (Microsporum and Trichophyton species) inactivated product are licensed for the
prevention and treatment of dermatophytosis in cats in some countries in Europe. None are
currently available in the USA or Canada. Limited evidence exists to support the safe use of these products as part of a comprehensive treatment protocol in cats with proven infection, but little evidence is available to support their use for prevention of infection.20,21
Recommendations for vaccination of shelter-housed cats
Generally, shelter-housed cats (Figure 3) can be considered to be at especially high risk of exposure to infectious disease. Endemic disease, high rates of turnover, stress and sustained exposure are contributing factors.
Vaccination in shelters should be limited to those diseases that are likely to be transmitted within the shelter itself. For diseases of concern in shelters (notably FPV and upper respiratory infections), vaccines may be indicated at an earlier age, and be administered at shorter intervals compared with schedules for pet cats. Rapid onset of protection is critical; therefore, administration of FPV, FHV-1, FCV vaccines should be considered for all cats at the time of (or ideally, before) intake.
Table 3 summarizes vaccination recommendations for shelter-housed cats.
Additional considerations when vaccinating shelter-housed cats
< Bordetella bronchiseptica and Chlamydophila felis vaccination The benefit of routine vaccination of shelter-housed cats against these disease agents is limited. The association between B bronchiseptica isolation and disease in shelters is inconsistent31–34 and C felis is not commonly isolated from shelter cats with upper respiratory infection.31 These vaccines should only be considered if the pathogens have been demonstrated as a current problem by laboratory diagnostics.
B bronchiseptica vaccination should also be used where there is potential direct or indirect contact between cats and dogs on the same site, and the dogs have a recent or current history of infectious respiratory disease.
< FIV and FIP vaccination Vaccination of shelter-housed cats against these agents is not
generally recommended.
< Dermatophytosis vaccination See comments in the household pet cats section.
Recommendations for vaccination of cats in trap–neuter–return programs
Most community cats (Figure 4, ie, free-roaming unowned feral and stray cats) lack protective
antibody titers against FPV, FHV-1 and rabies.9,35 In one study, the vast majority of feral cats vaccinated once at the time of TNR surgery developed protective antibody titers against FPV and FCV by the time they were re-trapped for testing 2–3 months later, regardless of whether inactivated or modified- live vaccines were used.35 In contrast, only inactivated vaccines resulted in a high
rate of protective antibodies against FHV-1.35 In the same study, nearly all cats developed high antibody titers against rabies after a single dose of inactivated rabies vaccine.35
Vaccine licensing studies have demonstrated 3–4 year DOI following a single vaccine administered to laboratory kittens. This suggests that, while the first rabies vaccine may only be recognized by regulatory agencies as valid for a single year, it is likely that vaccinated cats are protected for much longer. It is the recommendation of the Advisory Panel that cats in TNR programs receive FPV,
FHV-1, FCV and rabies vaccines at the time of surgery.
Recommendations for vaccination of cats housed in breeding catteries
Breeding catteries are variable in size, population and the nature of available facilities. The cat population may number less than 10 individuals or more than 50. Cats of various ages and life stages are typically present and many catteries continue to house retired breeding individuals that have been neutered. Some also contain household pets that may or may not have access to outdoors. The facilities may be sophisticated enough to allow for segregation of subpopulations or all individuals may and vaccination history of the residents is well known, but some diseases, such as upper respiratory tract disease, may be endemic.
Vaccination programs should be limited to those diseases that are relevant to the cattery and should be determined by analysis of risk factors. When assessing the level of disease risk in catteries, factors to consider include:
< Rate of population turnover.
< Population size and density.
< Number of litters/year (Figure 5).
< Presence of endemic disease.
Transmission of infectious diseases is facilitated by group living, young kittens mixing with older kittens and adults, contact during mating, introduction of new cats, and movement of cats into and out of the cattery (eg, queens going to other catteries for breeding, return of previously sold cats, travel for cat shows or other exhibitions). Catteries assessed as low risk would be considered similar to pet
homes (Table 2), whereas catteries assessed as high risk would be considered similar to shelters
(Table 3), pet stores, etc. In high-risk environments, vaccines may be used at an earlier age than in pet cats, particularly for control of endemic upper respiratory tract disease. In general, vaccination may be started at an earlier age than in the pet cat population and revaccination intervals may be shortened. Breeders should be encouraged to work with a veterinarian to develop a comprehensive
wellness program that includes appropriate vaccinations for their specific situation.
Vaccination records should be kept for each individual in the cattery that include all relevant information (eg, antigen, brand, date, vaccination site, adverse events, etc).
Management and husbandry have an important impact on the health of individual cats in
catteries. Relevant references and resources should be consulted.36,37
Additional considerations when
vaccinating cats in breeding catteries
< FeLV and FIV vaccination Vaccination of
cats in breeding catteries against these agents
is not generally recommended. Vaccinate if
necessary by analyzing risk, as for household
pet cats and kittens (Table 2). The retrovirus
status of all cats should be known:
vaccination is not a substitute for testing and
isolation. Vaccination may be unnecessary if a
good testing program is in place and no cats
have access to the outdoors.13 If queens are
routinely sent to another cattery for breeding,
vaccination of breeding queens may be
considered.
< Rabies vaccination Cats in breeding
catteries in the USA must be vaccinated
against rabies according to state regulations.
Elsewhere, vaccination against rabies is not
generally recommended. Vaccinate if
necessary by analyzing risk, as for household
pet cats and kittens (Table 2).
< Bordetella bronchiseptica and
Chlamydophila felis vaccination The benefit
of routine vaccination of cats in breeding
catteries against these disease agents is
limited. These vaccines should only be
considered if the pathogens have been
demonstrated as a current problem by
laboratory diagnostics. When used, the
primary series should be administered
according to the manufacturer’s instructions,
with annual revaccination if the problem
remains endemic. In some countries, the
manufacturer states that Bordetella
vaccination is considered safe for pregnant
queens. However, in other countries,
datasheets advise that the vaccine should
not be used in pregnant or lactating queens
or in kittens less than 1 month of age.
< FIP vaccination Vaccination of cats in
breeding catteries against FIP is generally not
recommended as there is insufficient evidence
that the vaccine induces clinically relevant
protection. (See accompanying Disease
Information Fact Sheet – details on page 799.)
< Dermatophytosis vaccination See earlier
comments in the household pet cats section
(page 791).
Vaccine adverse events
Although the administration of biological
products can never be entirely free of risk, in
general currently available feline vaccines have
an excellent safety record. It is important to
report any known or suspected negative events
associated with vaccination, recognizing that a
temporal relationship between an event and
vaccine administration does not necessarily
imply causality. In the United States, veterinarians
are requested to contact the manufacturer
(Veterinary Technical Services) of the vaccine(s)
considered to be involved; veterinarians may
also report known or suspected adverse events
directly to the US Department of Agriculture.
In other countries procedures may vary, but,
in general, veterinarians should contact the
manufacturer and notify the appropriate regulatory
agency to report a vaccine adverse event
(eg, the Canadian Centre for Veterinary
Biologics [Canada]; the Veterinary Medicines
Directorate [UK]; the European Medicines
Agency [EU]. (See Appendix 1 [Adverse Event
FAQs] on page 805 for specific reporting forms
and instructions.)
The most commonly reported vaccine reactions
are lethargy, anorexia and fever for a few
days after vaccination, or local inflammation at
the site of injection.4,42,43 Rarely anaphylaxis is
seen. Because vaccines are biologically active
products, occasional adverse reactions associated
with vaccination are inevitable. It should be
recognized, however, that establishing causality
is often difficult, especially if the suspected
reaction is delayed (days or weeks).43
Prevalence and type of adverse reactions
Although post-vaccinal adverse events in cats
are considered rare, the true prevalence is
likely to be underestimated due to underreporting
by both veterinarians and owners.44
In the most substantial survey to date, adverse
reactions were reported for all cats presented
to Banfield Pet Hospitals in the United States
between 2002 and 2005.4 During this period,
more than 1.25 million doses of various vaccines
were administered to nearly 0.5 million
cats. Adverse reactions within 30 days of vaccination
were reported at a rate of 51.6/10,000
cats vaccinated (0.52%), with 92% of these
reactions occurring within the first 3 days.
Clinical signs described for 1699 of 2560 cats
with vaccination-associated adverse events
included lethargy (± pyrexia) in 54%, local
pain or swelling at the vaccine site (25%),
vomiting (10%), facial or periorbital edema
(6%) and generalized pruritus (2%). Death
was reported in four cats, and in at least two
of these it was attributed to anaphylaxis.
Although the vaccines used were predominantly
from one manufacturer, no vaccine type
was found to be significantly more likely to
cause local reactions. Administration of multivalent
FPV, FHV-1, FCV and Chlamydophila
vaccines was significantly more likely to be
associated with lethargy (± pyrexia) than
administration of vaccines without the
Chlamydophila component. The risk of an
adverse reaction was greatest in cats around 1
year of age and/or increased as the number of
vaccines administered concurrently increased.4
In another extensive study specifically investigating
local post-vaccine reactions, a prevalence
of 0.23% was reported.45 Previous large reaction
rates of around 1–3%,46–48 but some variation
in prevalence can be expected with the use
of different products, administration of multiple
vaccines at the same appointment, and
surveillance methods.
Hypersensitivity reactions
Anaphylaxis and allergic reactions
Anaphylaxis is perhaps the best characterized
immune-mediated hypersensitivity (type I)
reaction to vaccination, but it is rare (approximately
1–5/10,000 vaccines).4,46 In cats it may
manifest as vomiting, diarrhea, respiratory
distress, facial or generalized pruritus, facial
swelling and collapse.1,43,49
A careful risk assessment is needed when
considering the revaccination of cats with a
history of anaphylaxis. In cats that have
experienced an allergic reaction with true
anaphylaxis, revaccination should usually be
avoided. Vaccine excipients (inactive ingredients)
are thought to cause most type I hypersensitivity
reactions.4 Hence, where revaccination
is considered necessary, using a different
vaccine formulation and premedicating with
an antihistamine and glucocorticoids 20–30
mins prior to vaccine administration is recommended,
followed by close observation of the
patient for several hours.1,4
Depending on geographic location, the
requirement to vaccinate cats for rabies may
take precedence over medical considerations.
Veterinarians are urged to contact the appropriate
authorities to determine what the local
status is when concerns arise and whether the
individual may be excused from vaccination.
(See also 2006 Guidelines, Appendix 1:
Certificate of Exemption from Rabies
Vaccination – details on page 786.)
Other reactions
While other forms of hypersensitivity reactions
(types II, III and IV) almost certainly
occur in cats after vaccination, these are rarely
documented. Some forms of local reaction
probably reflect type IV reactions. Poly -
arthritis is occasionally seen after FCV vaccination
Rarely it may represent a form of type
III reaction, but it is mainly due to co-infection
with field virus or vaccine virus itself.50,51
(See Appendix 1 [General FAQs] ‘What is the
cause of lameness occasionally seen after FCV
vaccination?’, page 802.)
Update on feline injection-site sarcomas
(FISS)
Vaccine-associated sarcoma was first recognized
as an issue in cats in the early 1990s.
While initial studies suggested a risk of sarcoma
development in around 2/10,000 doses of
vaccine administered,52 which increased to
13–36/10,000 doses in other studies,53–55 current
estimates based on larger epidemiologic
studies (published between 2002 and
20074,45,56) suggest that the risk of sarcoma
development following vaccination is actually
very low (probably well below 1/10,000 doses
of vaccine).4,45
Although initial reports linked development
of sarcomas at vaccination sites with the
use of inactivated rabies57 or FeLV vaccines,52
and aluminum-based adjuvants, more recent
studies found no relationship between vaccine
type, brand or use of inactivated versus
modified-live vaccines and the risk of subsequent
sarcoma formation.56,58,59 The impact of
using the canarypox-vectored rabies vaccine
is still unclear. One retrospective study of
histo pathology samples showed no reduction
in the prevalence of FISS after the introduction
of this vaccine; however, the types of vaccine
used were not reported.58 In a recently published
case control study it was suggested that
there may be a lower risk of inducing sarcomas
with this vaccine than with other rabies
vaccines.59 Many of these studies have also
clearly shown that injections other than vaccines
also have the ability to induce sarcoma
formation.
No studies have been published that define
objective methods for reducing the risk of
FISS in individual
cats presented for
routine vaccination.
Based on our current
understanding of
this problem, it is
likely that vaccines
are not uniquely
implicated in the
development of
injection site sarcomas
in cats.56,60 FISS
risk following vaccination
likely results
from a complex
interaction of mul -
tiple extrinsic (eg,
frequency and numcomposition
of the injected product, etc) and
intrinsic factors (eg, genetic predisposition,
tissue response following injection, etc). The
presumed relationship between types of vaccine,
inflammation at the site of vacci nation61
and subsequent FISS development appears
complex at best and, if involved, is likely only
one among many factors that contribute to
FISS development.
Table 5 provides a brief review of considerations
and management options for the reduction
of FISS risk, taken from current publications.
None of these suggestions are known to
prevent or cure FISS.
When considering vaccine type, the
Advisory Panel recommends that the following
be taken into consideration. Recent studies
demonstrate that all vaccines carry some
risk of inducing FISS, as do at least some other
injectable products. Although current information
as outlined above does not clearly
show differences in risk of FISS development
between modified-live and inactivated vaccines,
some Advisory Panel members consider
that, on balance, risk might be mitigated
by the use of modified-live vaccines. There are
also other factors that may influence the
choice of live versus inactivated vaccines
(see Table 6 and Appendix 1 [General FAQs],
page 803). Overall, however, the Advisory
Panel concluded that, at the current time,
there is insufficient information to make
definitive recommendations to use particular
vaccine types to reduce the risk of FISS.
Post-vaccination monitoring
The Advisory Panel recommends that clinicians
and their staff instruct clients to monitor
the vaccine site for swelling or lumps in order
to detect potential sarcomas while they may
still be removed successfully. Biopsy of any
mass present is warranted if it (a) remains present
3 months after vaccination; (b) is larger than Rabies vaccination of cats
Where rabies vaccination of cats is required,
veterinarians may not have discretion to vary
from the manufacturer’s recommendations or
from requirements set forth by regulatory agencies.
Rabies vaccination requirements vary from
country to country and can vary significantly
within individual countries. In locations where
feline rabies vaccination is required by law, veterinarians
are obligated to be familiar with and
follow legal requirements when administering
rabies vaccines. Rabies vaccination recommendations
contained in these Guidelines do not
constitute vaccination requirements.
Medical record documentation
of vaccination
At the time of vaccine administration, the following
information should be recorded in the
patient’s permanent medical record:
< Vaccine(s) recommended for this patient.
< Date of vaccine administration.
< Identity (name, initials or code) of the
person administering the vaccine(s).
< Vaccine name, lot or serial number,
expiration date, and manufacturer of
vaccine(s) actually administered.
< Site and route of vaccine administration.
< Concurrent medications/therapy.
< Recommendations for future vaccinations.
Adverse events should be recorded in a
manner that will clearly alert all staff members
during future visits. Risks and benefits
of vaccination should be discussed with the
owner so that they can make an informed
choice. Consent should be documented in
the medical record to demonstrate that relevant
information was provided to the client
and that the client authorized the procedure.cm in diameter; or (c) is increasing in size
1 month after vaccination (the ‘3-2-1 rule’ –
see Table 5). It is recommended that multiple
needle biopsies or an incisional wedge biopsy
are obtained to reduce the risk of harvesting
non-representative biopsy material and to minimize
the risk of tracking tumor cells outside of
the future surgical field.
Legal considerations associated
with vaccination
Veterinarians in most countries are permitted
to use professional judgment in the selection
and use of licensed vaccines. Reference to these
Guidelines, therefore, is appropriate when
developing vaccination protocols for individual
patients even though the guidance may
vary from the manufacturer’s label recommendations
or data sheet (eg, annual revaccination
vs triennial revaccination for core vaccines).
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