Advisory on Feline Vaccines

Advisory on Feline Vaccines
Vaccinations are an essential part of our pets health. They help in the prevention of viruses/diseases that could be debilitating and even fatal to our pets lives.
Although no vaccine is 100 percent effective, the proper use of vaccines allows kittens the best opportunity to grow up as healthy, robust cats. Vaccination is not a trivial medical procedure. Rather, it is a simple procedure that initiates a complicated biological process, resulting in the immunization or protection of the cat against the infectious agent or agents involved. There are many factors that must be taken into consideration before vaccination occurs, and there are many complications that occasionally occur after vaccination. Because some problems can be life threatening, vaccination of cats should be done only by a veterinarian or under the supervision of a veterinarian.


The terms vaccination and immunization are often used interchangeably, but they are not synonymous. Vaccination refers to the process of giving the vaccine. Immunization refers to the process whereby the immune system recognizes the various foreign proteins or antigens present in the vaccine and produces antibodies and/or other aspects of the immune response against those antigens. This immune response provides protection for the cat against the specific infectious agent. The aim is that, in all cases, vaccination will result in immunization, but in reality, no vaccine or vaccination is 100 percent effective. Therefore, a small percentage of cats vaccinated against a particular disease will not be immunized against that disease.

Nature of the Vaccine

Several types of vaccines are available for vaccination of cats. First, inactivated vaccines are ones in which the infectious agent involved in the vaccine has been treated in some way (usually by chemicals), so that it no longer can infect and replicate within the host. These vaccines are considered to be safe, but they require more time to produce an immune response and they tend to produce a shorter period of immunity.

A second type of vaccine is the modified live-virus (MLV) vaccine (also referred to as an attenuated vaccine), which contains viruses that have been altered by various techniques, so that they no longer produce clinical disease. Viruses in these vaccines can replicate within the host and stimulate a rapid and excellent immune response. In some cases, vaccine virus may be shed from the vaccinated cat to infect other cats that may come in contact with the vaccinated cat. MLV vaccines should not be administered to pregnant cats.

A third type of vaccine is the subunit vaccine. In this type of vaccine, a portion of the infectious agent is separated from the rest of the agent and serves to stimulate the immune system of the cat to develop antibodies against the whole virus or agent. Because there is no living virus or agent present, subunit vaccines are considered to be safe.

Genetically engineered vaccines are a fourth type of vaccine. There are a number of researchers working on genetically engineered vaccines, especially recombinant (involving genetic exchange) vaccines. In the future, we will probably see a number of unique recombinant vaccines for various infectious diseases of the cat.

Route of Vaccination

The route by which the vaccine is administered may affect the speed and degree of protection provided. In all cases, vaccines should only be administered according to the directions from the manufacturer or the veterinarian. Feline panleukopenia (FP) vaccine can be given intramuscularly (IM) or subcutaneously (SQ) with equal effect. Certain MLV-FP vaccines can also be given by the intranasal (IN) route, but they will not result in immunization if administered orally. Most rabies vaccines must be given by the IM route.

The MLV respiratory vaccines appear to be slightly more effective by the IM route, but they can be given SC. Vaccines licensed for IM or SC vaccination must not be given by the IN route.

The IN respiratory vaccines are administered by allowing the cat to inhale drops of vaccine into the nostrils. One or two drops are also placed in each eye (into the conjunctival sac). These vaccines produce rapid local, as well as systemic, immunity. Owners should be aware that vaccinated cats may sneeze and develop mild ocular and/or nasal discharge four to seven days after IN vaccination. Occasionally, ulcers may develop on the tongue after vaccination. Vaccinated cats shed vaccine viruses for long periods after IN vaccination.

Precautions for Vaccination

Although vaccination may appear to be a simple, innocuous procedure, there are several potential adverse effects and several precautions concerning vaccination of cats that must be kept in mind. Therefore, it is recommended that vaccines be administered only by licensed veterinarians, by licensed animal health technicians, or by animal owners under the supervision of a licensed veterinarian. Although severe reactions to vaccination are not common, lifethreatening reactions on occasion do occur. A trained professional must be available to administer life-saving medications if such a reaction does occur.

A vaccine is only as good as the quality maintained during production. Therefore, only vaccines obtained from reputable companies, where adequate quality control is maintained, should be used.

The following are specific precautions or possible adverse effects that might be encountered when vaccinating cats.

PRODUCTION OF DISEASE FROM VACCINE. If the vaccine virus is not modified sufficiently, clinical disease can result from the vaccination. Examples are mild respiratory disease after intranasal vaccination, and clinical rabies following vaccination with a living vaccine not licensed for use in the cat. Improperly prepared vaccines may contain the virulent virus. Also, the stress of vaccination may trigger a latent infection into becoming a clinical disease.

EFFECT ON FETUSES. Developing fetuses are much more susceptible to damage by vaccine viruses than are kittens or adult cats. Fetal death, abortions, resorptions, or congenital birth defects can be the result of vaccination of a pregnant cat with certain vaccines.

ALLERGIC REACTIONS. Occasionally severe and even fatal allergic or anaphylactic reactions can occur after vaccination. With appropriate knowledge and medication, these reactions can be counteracted.

VACCINE-ASSOCIATFD SARCOMAS. Recently, it has been noted that various types of sarcomas (certain types of cancer) may develop at the site of vaccination, particularly with inactivated vaccines (e.g., feline leukemia virus vaccines and rabies virus vaccines). The occurrence of tumors is apparently quite low-estimated to be from one to four per 10,000 vaccinates-but it is a potentially very severe consequence. Many researchers are actively investigating this problem. In the vast majority of outdoor cats, the risk of a cat contracting the infectious disease if not vaccinated is much greater than the risk of sarcoma development; routine vaccination continues to be strongly recommended.

INFECTION. Improperly handled equipment and vaccines can become contaminated with bacteria, resulting in abscess formation and/or generalized bacterial infections.

NERVE INJURY. An improperly placed injection can cause injury to a peripheral nerve with resulting lameness or paralysis.

FAILURE OF VACCINE TO IMMUNIZE. The use of vaccines that have lost their immunizing ability, the vaccination of kittens that still have maternally derived immunity, and the vaccination of immunocompromised cats are examples of the situation that may result in vaccine failure. Exposure to virulent virus later will result in severe clinical disease.

Age of the Cat

The most frequent cause of vaccine failure with feline panleukopenia (FP) vaccines is interference caused by maternally derived immunity. Nature has devised a marvelous method of providing temporary protection to young animals by passing immunity in the form of specific antibodies from the mother to the newborn through the first milk, or colostrum. Thus, kittens born to immune queens are solidly protected for a few weeks, but these kittens eventually become susceptible after the passive immunity wanes. The level and duration of passive immunity following nursing are determined by the antibody titer (concentration of antibody in serum) of the queen at parturition. Although the majority of kittens can be immunized successfully at eight to ten weeks of age, occasional kittens may not be susceptible to immunization until twelve weeks of age or older. Therefore, if FP vaccines are given at ages less than twelve weeks, they should be repeated at three- to four-week intervals until the cat is at least twelve weeks old.

The same principles of colostral transfer, antibody half-life, and vaccine virus neutralization apply to the respiratory viruses, feline herpesvirus type 1 (FHV-1), and feline calicivirus (FCV). There will be interference with respiratory vaccines if the maternally derived titers are high enough. Generally, the FHV-1 and FCV antibody titers are much lower than the FP titer, and therefore the duration of interference (and passive protection) is much shorter. This protection generally does not last longer than five to six weeks for FHV-1, and seven to eight weeks for FCV. By eight to ten weeks of age, the vast majority of cats can be successfully vaccinated against FHV-I and FCV.


Feline Panleukopenia -- Feline panleukopenia is caused by feline parvovirus (FPV). The virus remains infectious for months to years in the environment and is primarily spread via the fecal-oral route. Fomites (eg., cages, food and water bowls, litter boxes, and health care workers) play an important role in the transmission of the organism. Clinical sips of infection include lethargy, anorexia, vomiting, diarrhea, fever and profound panleukopenia; mortality rates are highest in young susceptible cats. In utero infection with FPV is a common cause of cerebellar hypoplasia.

Vaccination against PPV is highly recommended for all cats. Immunity to feline panleukopenia is primarily through antibody response to natural infection vaccination, or passive transfer of maternal antibodies from queen to kittens. Maternal antibody my interfere with immunization when antibody titers we high during the neonatal period. Maternal antibody titers generally want sufficiently to allow immunization by 12 weeks of age. Inmunity conferred by feline panleukopenia vaccines is considered to be excellent. and most vaccinated animals we completely protected from infection and clinical disease. Both serologic and challenge exposure data indicate that a parenteral FPV vaccine induces immunity that is sustained for at least 7 years. Therefore, following the initial series of vaccinations and revaccination 1 year later, cats should be vaccinated no more frequently than once every 3 years.

Modified-live virus (MLV) vaccines mid adjuvanted inactivated virus vaccines for parenteral administration and a MLV vaccine for topical (intranasal) administration art available and effective. Experimental studies have shown that intranasal administration of canine parvovirus2 vaccines to puppies is less effective than parenteral administration in overcoming maternal antibody interference. The most likely reason is that fewer virus particles reach lymphoid tissue when the product is given intranasally, as compared with parenteral administration, and viral replication in lymphoid tissue is required for immunization with MLV parvovirus vaccines. Although studies have not been performed in cats, the same phenomenon may occur in this species as well. Therefore, caution is appropriate when contemplating the use of intranasal FPV vaccines for primary immunization of kittens, especially those residing in environments where exposure to FPV is likely.

It has recently been found that some cats with panleukopenia-like disease were infected with canine parvovirus-2b (CPV-2b). Studies show that FPV vaccines provide excellent protection not only from FPV but also from CPV-2b; thus, canine parvovirus infection should not be a concern for cats immunized as a result of vaccination with FPV vaccines.

Serious adverse events associated with FPV vaccines are rare. Tumor formation at the site of a topically administered vaccine has not been reported. Vaccination of pregnant queens with modified-live FPV vaccines may possibly result In neurologic disease in developing fetuses; the same concern applies to kittens vaccinated at less than 4 weeks of age. Therefore, the use of MLV vaccines should be avoided in pregnant queens and kittens less than I month of age.

Feline viral rhinotracheitis and Feline calicivirus Infection. Feline viral rhinotracheitis, caused by feline herpesvirus-1 (FHV1), and feline calicivirus (FCV) infection account for up to 90% of all cases of infectious upper respiratory tract disease in cats. Both viruses are shed in ocular, nasal, and pharyngeal secretions of infected cats. Organisms an transmitted from cat to cat directly, through sneezed macro-droplets, or indirectly, via contaminated fromites. The disease is self-limiting; however, infected cats may develop chronic oculonasal disease. Latent infection is lifelong for cats inflected with FHV-1; reactivation can occur during periods of stress or following corticosteroid administration. Some cats infected with FCV become persistently infected and shed virus for prolonged periods (months to years). Although rarely serious in adult cats, disease caused by these viruses may be severe, and sometimes fatal, in kittens. Lameness and chronic oral inflammatory syndromes have been linked to calicivirus infection and vaccination with modified-live calicivirus vaccines. Risk of exposure to either FHV- I or FCV is high, because both organisms an widespread in the feline population.

Vaccination against FHV-1 and FCV is highly recommended for all cats. Immunity is through humoral and cell-mediated immune responses to natural infection or vaccination or through passive transfer of maternal andbodies from queen to kittens. Maternal antibody may interfere with induction of a systemic immune response; however, by 12 weeks of age. maternal antibody titers wane sufficiently to allow parenteral immunization. Topically administered (intranasal. conjunctival) vaccines am capable of inducing a local immune response in the face of high maternal antibody titers. Serologic and challenge exposure data indicate dud a parenteral FHV-1 and FCV vaccine induces protection that lasts at least 3 years. Therefore, following the initial series of vaccinations and revaccination I year later cats should be vaccinated once every 3 years.

Regardless of the route of administration, FHV-1 and FCV vaccines induce only relative, not complete, protection. At best, these vaccines induce an immune response that lessens the severity of disease, vaccinates me not immune to infection, nor are they protected from. all signs of disease. Currently available FCV vaccines probably do not induce protection from all isolates of the virus.

Modified-live virus and inactivated virus vaccines for parenteral administration and MLV vaccines for topical (intranasal and conjunctival) administration are available. If a susceptible cat is born into or is entering an environment in which viral upper respiratory tract disease is endemic (eg, some catteries, boarding facilities, and shelters), the use of A topical product may be advantageous. Administration of such products to kitten as young as 10 to 14 days of age could be considered in these situations; however, products that also contain modified live FPV antigens should not be administered to kittens younger than 4 weeks of age. Adverse events associated with vaccination against FHV-1 and FCV include mild transient fever, sneezing, conjunctivitis oculonasal discharge, lameness, and, for parenteral products, pain at the injection site. Sneezing, conjunctivitis, oculonasal discharge, and ulceration of the nasal philtrum are believed to occur more frequently with vaccines licensed for topical use. Tumor formation at the site of a topically administered vaccine has not been reported.

Rabies--Rabies is transmitted mainly through bite wounds of infected mammals. More cats than dogs develop rabies in the United States, and although relatively resistant to rabies, both species serve as potential sources of infection for human beings. Treatment is ineffective in cats that develop clinical signs and should not be attempted because of the high potential for zoonotic infection. All instances of suspected or known rabies virus infection must be reported to local health department officials. Proper precautions and quarantine procedures as outlined by local regulations and described in the "Compendium of Animal Rabies Prevention and Control" should be followed.

Although vaccine-associated sarcomas hive been reported to develop in association with administration of a variety of vaccines, current data suggests they are more frequently associated with administration of feline leukemia virus vaccines and adjuvanted rabies virus vaccines. Inflammatory reactions am commonly observed at sites where adjuvanted rabies virus vaccines have been administered, and concern has arisen regarding the possible association between these reactions and vaccineassociated sarcomas. With the exception of a recently approved canarypox virus-vectored recombinant feline rabies vaccine (PureVax Feline Rabies Vaccine, Merial Ltd), all rabies virus vaccines currently on the market contain adjuvants. In rats, inflammation induced by the recombinant product appears to be minimal, but whether the use of this vaccine will be associated with a reduced likelihood of vaccine-associated sarcoma formation in cats is not yet known. The recombinant product is currently licensed only for annual administration.

Rabies virus vaccination is highly recommended for all cats, and is required by law in some states and municipalities. Manufacturers are required by the USDA to establish, by means of experimental challenge exposure studies, the minimum duration of immunity for rabies virus vaccines they sell, and products approved for use every year or every 3 years are available. Statutes governing the administration of rabies virus vaccines vary considerably throughout the United States; veterinarians should comply with the legal requirements of their area.

Feline leukemia virus Infection- Feline leukemia virus (FeLV) infects domestic cats throughout the world. Transmission is through transfer of virus in the saliva or nasal secretions resulting from prolonged intimate contact (e.g., mutual grooming), biting, or sharing of food and water utensils. The virus may also be transmitted by transfusion of blood from an infected cat, in utero, or through the milk. Exposure to virus persisting in the environment, on fomites or in aerosolized secretions is not an efficient means of viral transmission. Clinical signs of FeLV infection are primarily related to neoplasia, anemia, and diseases resulting from immunosuppression.

Kittens am the most susceptible to infection; resistance increases with maturity Experimental data demonstrate that kittens younger than 16 weeks of age are most susceptible to infection. with cats older than this being relatively resistant. Cox at greatest risk include outdo" cam (freeroaming pets, stray cats, and feral cats). Also at risk are cats residing in open, multiple-cat environments, cats living with FeLV-infected cats, and cats residing in households with unknown FeLV status.

The decision to vaccinate an individual cat against FoLV infection should be based on the cat's age and its risk of exposure. Vaccination against FeLV is recommended for cats at risk of exposure (i.e., cats not restricted to a closed FeLV-negative, indoor environment especially those younger than 4 months of age. Vaccination is not recommended for cats with minimal to no risk of exposure, especially those older than 4 months of age. The ability of a particular vaccine brand to induce an immune response sufficient to resist persistent viremia varies from study to study. Because protection Is not induced in all vaccinates, preventing exposure to infected cats remains the single best way to prevent FeLV infection. Vaccination against FeLV does not diminish the importance of testing cats to identify those that are viremic. It is of critical importance that viremic cats not be in contact with other cats, especially those younger than 4 months of age. Therefore, the FcLV infection status of all cab should be determined. Adverse events associated with vaccination against FeLV include local swelling or pain, transient lethargy or fever, and postvaccination granuloma formation. Although vaccine-associated sarcomas have been reported to develop in association with administration of other vaccines, current data suggests they are more frequently associated with administration of FeLV vaccines and adjuvanted rabies virus vaccines. If vaccination is deemed appropriate, annual revaccination. is recommended. Cats should be tested for FeLV infection before initial vaccination and when then is a possibility that they have been exposed to FeLV since they were vaccinated. The ELISA is the preferred screening test; the IFA is the preferred confirmatory test. Individuals confirmed to be infected with FeLV need not receive FeLV vaccines but they should be segregated from uninfected cats.

Chlamydiosis - Chlamydia psittaci is a bacterial pathogen of the conjunctiva and respiratory tract of cats. Transmission is through, direct cat-to-cat contact fomite transmission is less likely became the organism is unstable in the environment. Serous conjunctivitis, which. may initially affect only 1 eye, is the most common clinical sign. Sneezing or nasal discharge may develop, but if so, are usually mild. Clinical signs are usually evident 5 to 10 days after infection and resolve with appropriate antimicrobial treatment. Isolation rates have been reported to range from approximately I% for cats without signs of respiratory tract disease to approximately 14% for cats with concurrent upper respiratory tract disease. Highest rates of infection are reported for cats between 5 weeks and 9 months of age. Immunity conferred by C. psittaci vaccines is similar to that conferred by FHV- I and FCV vaccines in that vaccinates are protected from seven clinical disease but not from infection. The frequency of adverse systemic events associated with C. psittaci vaccines is higher than that associated with other commonly used vaccines; reactions include lethargy, depression, anorexia, lameness, and fever 7 to 21 days after vaccination. Because signs of disease associated with C. psittaci infection are comparatively mild and respond favorabty to treatment and because adverse events associated with use of C. psittaci vaccines are of greater concern than adverse events associated with we of many other products, routine vaccination against C, psittaci infection is not recommended. Vaccination may be considered for cats in multiple-cat environments whom infections associated with clinical disease have been confirmed. If vaccination is deemed appropriate, annual revaccination is recommended.

Feline infectious peritonitis--Feline coronaviruses (FCoV) vary considerably in pathogenic potential and have historically been grouped into 2 biotypes: feline enteric coronaviruses (FECV) that typically cause subclinical to Mild enteric infections, And feline Infectious peritonitis viruses (FIPV) that cause feline infectious peritonitis (FIP). Currently, FIPV we believed to be generated as mutant variants in FECV-infected cats. PCoV am widespread in feline populations worldwide, with seropositivity rates highest in crowded multiple-cat environments. Transmission of the virus is mainly via the fecal-oral route, In environments in which FCoV infection is endemic (eg, most multiple-cat environments), 35 to 70% of cats will be shedding PCoV in the stool at any given time. Most infected cats remain healthy, although a few usually between I and 5%--ultimately develop FIP. Affected cats rarely survive regardless of treatment. Kittens are most often affected with FIP, but the disease reportedly can develop in cats of all ages. A genetic predisposition has been suggested, with higher disease incidence in certain lines.

Considerable controversy surrounds the ability of the currently available FIP vaccine (Primucell-FIP, Pfizer Animal Health) to prevent disease. Some studies demonstrated protection from disease; others show little benefit from vaccination. Antibody-dependent enhancement (ADE) of disease in vaccinates has been demonstrated in experimental challenge exposure studies, but it is uncertain whether ADE occurs in a natural setting. Discrepancies between study results are probably attributable to differences in test methodology (eg, strain and dose of challenge virus, genetic predisposition of the test animals). Protection from disease has not been demonstrated in animals vaccinated when younger than 16 weeks of age. However, most kittens born and reared in environments in which FCoV Infection is endemic an infected prior to reaching this age. In these instances, vaccination of infected cats has not proven beneficial. At this time, them is no evidence that the vaccine induces clinically relevant protection, and its use is not recommended.

Dermatophytosis--Dermatophytosis in cats is primarily caused by infection with Microsporum canis. A variety of clinical manifestations, including transitory clinical disease and chronic infection with or without clinical sips, have bow reported. Although successful treatment of individual cats is usually straightforward, elimination of endemic infection from multiplecat environments is expensive, labor intensive, and time consuming.

An M. canis vaccine (Fel-O-Vex MC-K, Fort Dodge Animal Health) is approved for use as an aid in the prevention and treatment of clinical signs associated with M. canis infection. Vaccination has not been demonstrated to prevent infection or to eliminate M. canis organisms from infected cats. Therefore, routine vaccination against M. canis infection is not recommended. At the time of this writing, the product has not been independently evaluated for efficacy. Based on studies conducted by the manufacturer, it is reasonable to consider vaccination as adjunctive treatment for individual infected cats 4 months of age or older to hasten resolution of clinical signs. If the vaccine induces an immune response that accelerates lesion resolution, then the number of infectious fungal spores produced by vaccinates my be reduced as well; therefore, it is reasonable to consider vaccination as one component of a comprehensive treatment program in multiple-cat environments in which M. canis infection is endemic. Nonetheless, the ability of this product to hasten elimination of endemic infections from such environments has not been evaluated. The revaccination interval is not stipulated on the label. Major adverse events reportedly associated with the use of this product are pain, temporary hair loss, and formation of sterile abscesses or granulomas at the vaccine site.

Bordetella bronchiseptica Infection -- Bordetella bronchiseptica is a small, aerobic, gram-negative coccobacillus long recognized as a respiratory tract pathogen of several species of animals. The natural route of transmission in cats is believed to be via the aerosol or intranasal route. Experimental challenge exposure studies have shown that B. bronchiseptica can act as a primary pathogen in cats, inoculation of specific-pathogen-free (SPF) kittens results in self-limiting disease characterized by variable degrees of fever, nasal or ocular discharge, sneezing, induced or spontaneous coughing, pulmonary tales, and submandibular lymphadenopathy. Bronchopneumonia associated with naturally occurring B. bronchiseptica infection has been reported in both kittens and adult cat. Other factors, including nutritional status, overcrowding, co-infection With other agents such as FCV or FHV- 1. and suboptimal hygiene, may influence the outcome of exposure.

Seroprevalence surveys suggest that exposure to the organism is common, with infection raw varying from population to population. The highest rates of seropositivity (often > 80%) am found among cats in rescue shelters and multiple-cat households, especially when am is a history of respiratory tract disease. Lowest rates are found among cats in households with few cats and no history of respiratory tract disease 54-55 Similarly. isolation rates vary. B. branchiseptica was isolated from the oropharynx of 19 of 614 ( 3.1 %) and from the distal trachea in 6 of 614 (1%) of asymptomatic cats from shelters in Lousiana. In a recent survey of 740 cats in the United Kingdom, none of the household cats were found to be infected. but 9% of cats from breeding colonies, and 19% of cats from rescue shelters were found to be carrying the organism. In the same survey, 9% of healthy cats and 14% of cats with respiratory tract disease tested positive for the organism. An additional finding was a strong positive association between oropharyngeal isolation of B. bronchiseptica and residence in households containing dogs with a recent history of respiratory tract disease.

Definitive diagnosis of disease associated with B. bronchiseptica infection may be difficult, in pan because signs of infection often mimic those associated with FHV-1 or FCV infection. Isolation of B. bronchiseptica from a cat with respiratory tract disease is supportive of the diagnosis, but carriage of the organism in asymptomatic cats precludes establishing a direct cause-and-effect relationship. Resolution of disease with appropriately chosen antimicrobial medication might suggest a causative role for B. bronchiseptica. but the self-limiting nature of many cases of viral upper respiratory tract disease prevents attributing disease resolution solely to antimicrobial treatment.

A vaccine (Protex-Bb, Interval Inc) to prevent disease caused by infection with B. bronchiseptica has recently been licensed. The product contains a live, reducedvirulence culture of B. bronchiseptica and is licensed for administration via the intranasal route to cats 4 weeks of age and older. Efficacy of the vaccine has not been independently evaluated, but in studies conducted by the to gain vaccine licensure, vaccinated 4-week-old SPP cats experienced less severe signs of disease than did unvaccinated controls when challenge exposed 3 weeks after vaccination. Similar results were obtained when 8-week-old kittens were challenge exposed 72 hours after vaccination. As of this writing, studies to evaluate the duration of protection induced by the vaccine have not beer completed, and the revaccination interval is not yet stipulated on the label. Routine use of this vaccine is not recommened. It is reasonable to consider vaccinating cats entering or residing in multiple-cat environments (eg, shelters, catteries, or boarding facilities) where disease associated with B. bronchiseptica infection has been confirmed. However, the ability of the product to reduce the prevalence of infection or the severity of disease in such environments has not been evaluated.

Giardiasis--Infection of cats with the protozoan Giardia lamblia is associated with acute or chronic gastrointestinal disease ranging in severity from subclinical to severe. Because infected can shed cysts intermittently, diagnosis of G. lamblia infection is often cumbersome and usually requires multiple fecal examinations Several methods of diagnosis are available, including examination of a focal smear, the zinc sulfate centrifugation method, and use of an ELISA to test feces. There am currently no approved treatment methods for cats, and although treatment commonly controls signs of disease, it is uncertain that it clears infection. Treatment effectiveness is highly variable, and resistant organisms am commonly encountered. Giardia lamblia is transmitted via the fecaloral route, cysts may be ingested from contaminated water, from direct cat-to-cat transmission especially in crowded environments (eg, through mutual grooming), from exposure to contaminated litter boxes, and from consuming prey. Giardiasis is a recognized zoonotic disease, but the role of cats in transm6sion of the organism is not well established.

A vaccine has recently been licensed by the USDA (Fel-0-Vax Giardia. Fort Dodge Animal Health) as an aid in the prevention of disease associated with G. lamblia infection and reduction in the severity of shedding of cysts This vaccine is composed of quantified, homogenated, and chemically Inactivated G. lamblia trophozoltes, and contains an adjuvant commonly found in other feline products from the manufacture, but different from the adjuvant in die manufacturer's canine product. The vaccine is approved for use in cats 8 weeks of age and older. At the time of this writing, the vaccine has not been independently evaluated for efficacy, but in studies conducted by the manfacturer to gain vaccine licensure, vaccinates had a statistically significant reduction in severity of clinical signs (diarrhea), duration of cyst shedding, and prevalence of infection (percentage of cats with trophozoites at the end of the trial), compared with control animals. Protection was demonstrated to persist for at least I year after vaccination.

Routine use of this vaccine is not recommended, but because vaccinates had less severe clinical disease and shed cysts for a shorter time, it is reasonable to consider vaccination as part of a comprehensive control program in environments where exposure to G. lamblia is clinically significant. When parasite exposure is on-going, revaccination at annual intervals is recommended. Some vaccinates may died cysts subsequent to G. lamblia exposure, themfore, proper hygiene and sanitation practices should be implemented even with vaccinated cam The ability of this product to aid In hastening elimination of endemic infection from multiple-cat environments has not been evaluated.

Vaccination site Recommendations
  • Vaccines containing antigens from feline parvavirus, feline herpes-virus-1, feline calicivirus, or Chlamydia spp should be administered over the right shoulder as distally as practical, according to manufacturer's recommendations.

  • Vaccines containing feline leukemia virus antigen (with or without other antigens, except rabies virus antigen) should be administered in the left hind leg as distally as practical, according to manufacturer's recommendations.

  • Vaccines containing rabies virus antigen (and any other antigens) should be administered in the right hind leg as distally as practical, according to manufacturer's recommendations

  • For other intramuscular injections, the right hind leg should be avoided. Other subcutaneous injections should be administered on a side of the body or over the left shoulder as distally as practical.

  • Interscapular and spinous process regions should be avoided for all injections