Feline vaccination: Guidelines, indications, and risks (Proceedings)
A physical examination, fecal parasite screen, and vaccine needs assessment should be performed at least yearly for all cats. The American Association of Feline Practitioners (AAFP) recently published the third version of the Feline Vaccine Advisory Panel Report (Richards and colleagues 2006; http://www.aafponline.org/). These guidelines are an excellent source of information for veterinarians to use when individualizing vaccination protocols. Vaccine antigens were divided into those that were considered core (FPV, FCV, FHV-1, and rabies), noncore (FeLV, FIV, Bordetella bronchiseptica, and Chlamydophila felis), and not generally recommended (Giardia and FIP). The following recommendations were adapted from the AAFP Panel Report.
FPV, FCV, FHV-1All healthy kittens and adult cats without a known vaccination history should be routinely vaccinated with an intranasal or parenteral vaccine that contains FPV, FCV, and FHV-1 (FVRCP). Multiple modified-live products and killed products are available and the products available in the United States were recently reviewed (Richards and colleagues 2006). In general, modified live FVRCP vaccines are recommended for kittens housed in environments at high risk for exposure to FPV. Modified live FVRCP vaccines for intranasal administration can induce protection against FHV-1 as soon as four days after administration (Lappin and colleagues 2006a) and so this route of administration may be preferred for kittens housed in environments at high risk for exposure to FHV-1. Modified live products should not be administered to clinically ill, debilitated, or pregnant animals. Administration of intranasal FVRCP vaccines can induce transient, mild sneezing or coughing and so the owners should be informed.
For kittens thought to have no more than routine risk of exposure to FPV, FCV, or FHV-1, it is currently recommended that FVRCP vaccines should be administered starting no sooner than 6 weeks of age with boosters every 3-4 weeks until 16 weeks of age. Older kittens and adult cats with unknown vaccination history should be administered two killed or two modified-live FVRCP doses 3 to 4 weeks apart.
For kittens thought to have high risk of exposure to FPV, like those housed in animal shelters or pet stores, the AAFP panel currently recommends parenteral administration of modified live FPV containing vaccines as early as 4 weeks of age, particularly during an outbreak. However, intranasal administration of modified live FVRCP vaccines instead of or in addition to parenteral administration of modified live FVRCP vaccines may be superior for protection against FCV and FHV-1 in these environments.
The current AAFP Advisory Panel recommends a booster FVRCP vaccine one year later. However, a recent study showed that while there was no difference in FPV immunity, the relative efficacy of FCV and FHV-1 vaccines were lower at 1 year after initial vaccination than at 4 weeks after initial vaccination (Poulet 2007). The author concluded that the first FCV and FHV-1 booster vaccination after the completion of the initial series should be administered earlier than one year.
Based on several challenge studies, it appears that there is no need to administer FVRCP vaccines any more frequently than every third year after the one year booster vaccine; it is possible the duration of immunity is much longer. As previously discussed, serological test results for antibodies against FPV, FCV, and FHV-1 can be used to aid in the determination of vaccine needs (Lappin and colleagues 2002). Validated serological tests are available at New York State Veterinary Diagnostic Laboratory, Ithaca, New York and Heska Corporation, Loveland, Colorado.
Some variants of FCV induce systemic vasculitis in cats (virulent calicivirus) and clinical signs can be severe in some cats previously vaccinated with FVRCP vaccines (Hurley and colleagues 2004). A killed, virulent FCV containing vaccine line is now available (Fort Dodge Animal Health, Fort Dodge, Iowa). Whether it will be beneficial to administer this strain of FCV to cats is currently unknown. Factors to consider include 1. the prevalence of virulent FCV infections are unknown and currently are thought to be rare; 2. the virulent FCV strains characterized to date have been genetically and antigenically distinct and so it appears unlikely that a vaccine produced from one strain will cross protect against multiple strains; 3. the currently available vaccine line has only been shown to be effective against homologous challenge two weeks after completing the vaccine series; the maximal duration of immunity and whether the vaccine induces cross-protection against other virulent FCV or regular FCV strains is unknown. However, there may be benefit to having multiple FCV in feline vaccines to increase cross-protection against other FCV. The AAFP ( http://www.catvets.com/professionals/guidelines/feline_friendly/?Id=286/) has posted an informational brief on the topic
Rabies. All cats should be vaccinated against rabies. Rabies vaccine should be administered SC in the distal right rear limb at the age recommended by the vaccine manufacturer (as early as 8 week depending on brand) in accordance with state and local statutes. Cats should be vaccinated one year later and then either annually or triennially based on state and local statutes and the vaccine product used. The currently available live virus-vectored rabies vaccine (Merial, Duluth, Ga) induces less inflammation than killed rabies vaccines but whether this vaccine is less likely to be associated with soft tissue sarcomas is currently unknown.
The currently available B. bronchiseptica vaccine for intranasal administration can be administered as early as 4 weeks of age, has an onset of immunity as early as 72 hours, and has a minimum duration of immunity of 1 year. Many cats have antibodies against Bordetella bronchiseptica, the organism is commonly cultured from cats of crowded environments, and there are sporadic reports of severe lower respiratory disease caused by bordetellosis in kittens and cats of crowded environments or other stressful situations. However, the significance of infection in otherwise healthy pet cats appears to be minimal. For example, in client-owned cats in north central Colorado, the organism was rarely cultured from cats with rhinitis or lower respiratory disease (approximately 3%). In addition, because the vaccine is administered by the intranasal route, mild sneezing and coughing can result. Bordetella vaccination should be considered primarily for use in cats at high risk for exposure and disease, such as those with a history of respiratory problems and living in humane shelters with culture proven outbreaks. Since the disease is apparently not life-threatening in adult cats, is uncommon in pet cats, and responds to a variety of antibiotics, routine use of this vaccine in client-owned cats seems unnecessary.
Killed and modified live C. felis containing vaccines are available. Infection of cats by C. felis generally only results in mild conjunctivitis, is easily treated with antibiotics, has variable prevalence rates, and the organism is of minimal zoonotic risk to people. In addition, use of FVRCP vaccines that also contained C. felis was associated with more vaccine reactions in cats when compared to other products (Moore and colleagues 2007). Thus, whether C. felis vaccination is ever required is controversial. The use of this vaccine should be reserved for cats with a high risk of exposure to other cats and in catteries with endemic disease. Duration of immunity for Chlamydophila vaccines may be short-lived, so high-risk cats should be immunized before a potential exposure.