Establishing Vaccination Protocols for Catteries
by Susan Little, DVM, Dipl ABVP (Feline)
The release of the Feline Vaccination Guidelines by the American Association of Feline Practitioners/Academy of Feline Medicine earlier this year has provided cat owners and breeders alike with new information about vaccinating their cats. In many cases, breeders may be left wondering what the best strategy is for their cattery in the light of this new information. The AAFP Guidelines were not specifically directed toward breeders, but they contain information that can help in establishing vaccine protocols in catteries. In this article I hope to provide some guidance to breeders in selecting their own vaccination protocols.
It is important to note that we can no longer think in terms of a standard vaccination protocol for all cats. We must assess the relative risks for each cat, taking into account both individual and environmental factors, to make appropriate decisions. This means having knowledge not only of infectious diseases, but also of immunology. The individual health status of each cat or kitten being vaccinated must also be taken into account. Vaccination is truly a medical procedure with attendant risks and benefits, so considerable thought should go into these decisions. I would encourage all breeders to discuss these issues, including the AAFP Guidelines, with their veterinarian in order to reach decisions that are right for their individual circumstances. What is right for your cattery may not be right for another cattery, and what is right for one individual cat may not be right for another cat.
The AAFP Guidelines have designated feline panleukopenia (FPV), feline viral rhinotracheitis (FHV-1), and feline calicivirus (FCV) as "core" vaccines necessary for all cats. (Rabies is also included in the core group, but since local laws tend to govern the administration of this vaccine, we will not discuss it here.) For breeders, these core vaccines are likely the most important. Kittens must have adequate vaccination against these infectious diseases in order to survive kittenhood and to provide a sound basis for future health and vaccination decisions. The protocol we follow as breeders for our kittens will affect their entire future.
What type of vaccine do we pick? We generally have a range of modified live vaccines (MLV), killed virus vaccines (KV) and intranasal (IN) vaccines to choose from. There are also subunit and DNA vaccines available for some pathogens.
MLV must replicate in the cat after administration, so they more closely mimic a natural infection, thereby producing stronger immunity of longer duration than the other vaccine types. If droplets of a MLV inadvertently contact the mucous membranes of the cat (eyes, nose, mouth) or are licked from the haircoat, a mild form of the disease may be produced. The benefits of a high quality immune response from MLV are somewhat offset by rare occurrences of immunosuppression or vaccine-induced disease (most important in cats with suppressed immune systems, such as occurs with feline leukemia or feline immunodeficiency virus infection). Care must be taken to select the appropriate individuals for MLV administration.
KVs are generally believed to be safer than MLVs since they cannot replicate in the cat and are unable to cause disease. This is offset by a weaker immune response with a shorter duration. KVs also contain a larger dose of antigen than MLVs and almost always need an adjuvant (a substance that increases the immune response). These factors make KVs more expensive than MLV counterparts. In the case of rabies and FPV, it is believed that KV can induce immunity similar to MLV.
IN vaccines are a type of MLV designed for local administration (usually eyes and nose). They can produce a good systemic immunity as well as a local immune response and can provide a more rapid onset of protection. This local immune response is advantageous in the case of FHV-1 and FCV where the site of vaccination (eyes, nose) is also the target site of the disease.
For the lowest risk group of kittens, those in single pet homes, vaccination at eight and 12 weeks of age is appropriate. However, catteries represent a higher risk environment, especially if upper respiratory infection (URI) is endemic. In these situations it is appropriate to vaccinate earlier, although we must understand that vaccines generally have not been tested in animals under six weeks of age and their use in this manner is considered "off label." The earliest we can vaccinate a kitten in the highest risk situations is two weeks of age, since the lower body temperature of the neonatal kitten compromises its ability to mount an immune response before this. Vaccination before two weeks of age will provide little or no protection, and could possibly cause serious disease in some situations. We must also recognize that the ability of neonatal kittens to respond to vaccination varies greatly due to genetic and environmental factors that affect their immune system.
Various strategies are appropriate for catteries, including the use of IN vaccines. Breeders who produce only one or two litters per year could use the protocol for the lowest risk group mentioned above. Larger catteries without serious URI problems could use an injectable MLV for FHV-1, FCV, and FPV at four weeks of age, with subsequent vaccinations at eight and 12 weeks of age. Catteries with a high level of endemic URI could use IN vaccines for FHV-1 and FCV at two to four weeks of age by administering one drop in each eye and one drop in each nostril per kitten. This is followed by injectable MLV for FHV-1, FCV, and FPV at intervals of four weeks until 12-14 weeks of age. Good husbandry and isolation of kittens by age group are also very important factors in preventing disease in catteries.
In select situations, it may be appropriate to vaccinate pregnant queens with a three-way KV product or an IN product containing FHV-1 and FCV (but not FPV) in the last two to three weeks of gestation in order to provide optimal levels of antibodies to the kittens. In general, IN vaccines without FPV and KV are safe in pregnant queens, but we must realize that there is some risk in using them, mainly connected to the possible occurrence of a vaccine reaction. While the vaccine itself is not dangerous, the fever, lethargy or loss of appetite that could accompany vaccination might affect the unborn kittens detrimentally. This is a situation where it is especially important to assess the risks and benefits of vaccinating individuals.
It is important to note that booster vaccinations should not be given more frequently than every two weeks, with an interval of three to four weeks being ideal. We must also avoid administering any MLV containing FPV to kittens under the age of four weeks (or to pregnant queens). Even when vaccinating young kittens with an injectable vaccine (whether MLV or killed), a full dose should be given to each kitten (this does not apply to the use of IN vaccines in the two to four week age group). Using less than the full dose could result in inadequate production of immunity. It is also important to ensure each kitten receives a final vaccination at 12 weeks of age or later in order to avoid maternal antibody interference. Since we cannot predict how long maternal antibodies obtained by the kitten from its dam will persist in each individual, the age of 12 weeks is an appropriate rule of thumb.
A problematic issue is vaccination against Chlamydia psittaci, designated as a non-core vaccine. This pathogen is considered to represent only a small fraction of the URI cases in North America, although it may be more significant in other parts of the world. Approximately three percent of cats will have reactions to this vaccine which vary in severity. Typically, affected cats have lethargy, depression, anorexia, lameness and fever starting seven to 21 days after vaccination. The lag in time from vaccination to appearance of symptoms may increase the chances that the connection to the vaccine is not appreciated by owners and veterinarians. There is also concern that the quality of the immune response to Chlamydia vaccines is not as good as that for FHV-1 and FCV. With the advent of more promising antibiotic therapy for Chlamydia infections (i.e., azithromycin), inclusion of Chlamydia vaccines in a cattery's vaccination protocol warrants serious thought. Another issue that troubles many breeders is vaccination against feline leukemia virus (FeLV) and feline infectious peritonitis virus (FIP). These are both considered non-core vaccines and should only be administered to individuals at realistic risk of the disease. For many catteries, a regular testing policy for FeLV is preferable to vaccination alone, and may replace the need for vaccination against FeLV altogether. However, we must realize that not all kittens sold by breeders will be going to live in as controlled an environment as a cattery provides. In many cases, a kitten's environment will change in the first few years of its life. For instance, a kitten kept indoors when young may start venturing outside when a bit older, or a single-cat household may easily become a multi-cat household. For these reasons, and because the most susceptible period in a cat's life for FeLV infection is when young, many kittens will be appropriately vaccinated for FeLV after they arrive in their new homes. We must respect and acknowledge that the kitten's risk factors have changed and need to be reevaluated after purchase, and this may or may not include the need for FeLV vaccination.
The vaccine against FIP is a relative newcomer. The natural history of this virus is very complex and in many ways, the mode of transmission and development of disease are quite different from other common feline viruses. Most kittens are infected with the parent virus, the benign enteric coronavirus, before 16 weeks of age, which is the age recommended by the manufacturer for first vaccination. There continues to be controversy surrounding the safety and efficacy of this vaccine, with published studies showing conflicting results. Other methods of controlling the incidence of FIP are very useful, including early weaning protocols and selection for resistant breeding stock. The use of this vaccine in a cattery must be made considering all the factors involved and performed when the benefits of using it clearly outweigh any risks.
Once a kitten receives the appropriate vaccinations in the first year of life, what then? The first vaccination for all cats with the core vaccines should be one year after the last inoculation as a kitten. From this point, we cannot pick one protocol for all cats. Breeders should attempt to group their cats according to relative risk. For example, many catteries contain older spays or neuters that may be retired breeders or show cats. It may be appropriate for these individuals to receive boosters for FHV-1, FCV and FPV every three years as mentioned in the AAFP Guidelines. Cats being bred or shown regularly are at higher risk and it may be more appropriate to booster these individuals yearly until they are retired from breeding/showing. Revaccination of queens may be planned around their pregnancies, especially if the breeder has chosen to vaccinate some pregnant queens near the end of gestation. It is very helpful in disease prevention to divide a cattery into smaller colonies with cats grouped by age and status (i.e., retired versus actively breeding/showing versus young kittens).
An important issue for breeders and veterinarians alike is proper handling and storage of vaccines. This is probably an underappreciated cause of what may appear to be vaccine failure. All vaccines should be given only by the route specified by the manufacturer (i.e., vaccines intended for intramuscular injection should never be given subcutaneously). We must recognize that all vaccines can be adversely affected by environmental factors and handling. Heat, excessive cold, and exposure to ultraviolet light can all inactivate vaccines. Such conditions could easily occur during shipping. In addition, vaccines should never be mixed together in the same syringe other than as the manufacturer intended. Any vaccines that have to be reconstituted should be diluted only with the diluent provided by the manufacturer and they should be used as soon as possible after reconstitution.
Finally, I would like to emphasize the importance of accurate record-keeping in the cattery. Just as records should be kept about reproductive history, good records must be kept on the health status and vaccination history for each litter and each adult. The vaccine site recommendations established by the AAFP and the Vaccine Associated Feline Sarcoma Task Force should be followed. Anyone administering vaccines should take care to record pertinent information carefully as outlined in the AAFP Guidelines and reported in Feline Vaccine Guidelines by Dr. Diane Eigner in the April 1998 issue of the Almanac. This also includes recording any adverse reactions to vaccination and reporting them to the appropriate authority (such as the U.S. Dept. of Agriculture, the Canadian Food Inspection Agency, the USP Veterinary Practitionersâ Reporting Network, and the vaccine manufacturer). As time goes by we will have not only more information on the duration of immunity provided by vaccines from ongoing studies, but also new vaccine technologies to choose from. DNA-based vaccine technology and genetic engineering will potentially help solve some of the current vaccine problems by removing both adjuvants and antigens from the vaccine. We will also see the advent of more vaccines against a wider range of problems, from parasites to pregnancy to infectious diseases. We will continually have to reevaluate our vaccination strategies to accommodate the changes to come, but hopefully the outcome will be improved disease prevention at a lower risk for all cats.