Today's Veterinary Practice

MAY-JUN 2013

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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| ViTal VaccinaTion SerieS: anTibody TiTerS VerSuS VaccinaTion to accurately represent a defined threshold of antibody. Both in-clinic tests have been correlated through VN, HI, or challenge testing results. While the correlation studies were conducted independently through universities, the data is available through the respective companies that manufacture the in-clinic test kits. Today, in-clinic titer test kits for canine distemper (CDV), canine parvovirus (CPV), canine adenovirus (CAV), and feline parvovirus (panleukopenia, FPV) correlate well with appropriate gold standard tests. Therefore, when these inclinic tests are performed properly: • A positive test result indicates the patient does have protective levels of antibody against the virus. • A negative test result indicates the patient does not have protective levels of circulating antibody. However, a negative test result does not necessarily define susceptibility. IT'S ALL ABOUT PIE • Protection(P): Some, but not all, antibody results correlate well with protection (eg, canine and feline parvovirus). a patient with a positive titer or test result for parvovirus antibody can be considered protected. • Infection(I):on the other hand, antibody presence can represent evidence of active infection (eg, feline immunodeficiency virus). • Exposure(E):other antibody test results indicate prior exposure to an infectious agent (eg, ehrlichiosis) or vaccine (eg, rabies) and do not predict either protection or active infection. ANTIBODY DEVELOPMENT LIMITATIONS Seroconversion, the antibody response that follows vaccination, can be identified for most vaccines administered to dogs and cats. However, the development of antibody does not necessarily equate to protective immunity. Feline Calicivirus & Herpesvirus • Even if antibody test results are positive after feline herpesvirus (FHV) and feline calicivirus (FCV) vaccination, results do not correlate well with protective immunity; these results are not generally recommended for use when making vaccination decisions for an individual cat. • The correlation between the gold stan- 36 dard antibody test for FHV-1 (VN) and protection is only fair; cell-mediated immunity is a better correlate of protection against FHV-1. • The correlation between the gold standard test for FCV (VN) and protection is fair to good. Rabies Rabies antibody titers, as determined by fluorescent antibody virus neutralization (FAVN), are only available through a limited number of certified laboratories. It is important to note that a rabies virus antibody titer cannot be interpreted as an index of immunity in lieu of revaccination. Factors that influence antibody response followingvaccinationinclude: • • • • age antigen type Vaccination history Health status • Genetics • Maternally-derived antibody (Mda) INDICATIONS FOR ANTIBODY TESTING The following indications apply to antibody tests for CAV1, CDV, CPV, and FPV because these results correlate well with gold standard testing: 1. Evaluation of Immune Response Following Initial Administration of Core Vaccines If a client would like to determine whether a young dog/ cat responded to the initial vaccination series (usually 3 doses), in-clinic test kits provide an excellent means of identifying those that did respond versus those that did not and, therefore, remain susceptible. 2. Management of Infection Among Vaccinates For veterinarians faced with treating confirmed parvovirus infection in a well vaccinated dog or cat, antibody testing can be used to rapidly determine whether the affected TABLE 1. Tests to Determine Immunologic Protection VIRUS APPROPRIATE TESTS Rabies rabies antibody titers are determined by FaVn. Test results cannot be used as an index of immunity in lieu of revaccination. CANINE Adenovirus in-clinic titer test results correlate well with gold standard testing (Vn). Distemper virus in-clinic titer test results correlate well with gold standard testing (Vn). Parvovirus in-clinic titer test results correlate well with gold standard testing (Hi). FELINE Calicivirus The correlation between gold standard testing (Vn) and protection is fair to good. Herpesvirus The correlation between gold standard testing (Vn) and protection is only fair; cell-mediated immunity is a better correlate of protection. Parvovirus in-clinic titer test results correlate well with gold standard testing (Hi). Today's Veterinary Practice May/June 2013

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