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ViTal VaccinaTion SerieS: anTibody TiTerS VerSuS VaccinaTion | TABLE 2. In-Clinic Antibody Titer Test Kits TiterCHEK VacciCheck Antibody Test Kit Manufacturer Synbiotics corporation (synbiotics.com) biogal Galed laboratories (biogal.co.il) Canine Antibody cdV and cPV caV, cdV, and cPV Feline Antibody none FcV, FHV, and FPV Sample Serum or plasma (can use hemolyzed sample) Serum, plasma, or whole blood (can use hemolyzed sample) Test Time 15–20 min (minimum) 21 min (minimum) Results Qualitative: Positive or negative Semiquantitative (based on color): negative, low positive, significant positive, or high positive animal developed a protective immune response following the initial vaccination series. • A positive antibody test suggests the vaccinated patient was infected during a period of susceptibility (eg, in the presence of MDA). • Patients with a negative test result are likely to be susceptible (genetic) non-responders (or low-responders). • The antibody test does not distinguish vaccine-induced seroconversion from that caused by infection. 3. Determination of Antibody Level in Lieu of Revaccination For patients with a history of a known, or suspected, serious vaccine adverse event (reaction), evaluating the level of antibody will determine whether the patient has previously developed a protective immune response to vaccination. Patients with a positive test result can avoid revaccination and potential risk for an adverse event. If, on the other hand, a patient with a history of a serious vaccine adverse event is tested for antibody and has a negative test result, the decision whether or not to administer vaccine is more complicated because: • Among previously vaccinated animals, immune memory (B-lymphocytes) can be sustained for many years despite declining antibody levels; exposure to a pathogenic virus (eg, distemper or parvovirus) can result in a rapid and protective anamnestic response. • Prior history of a vaccine adverse reaction is not predictive of future risk. • Immunization may not be optional, regardless of the antibody status of the individual (eg, rabies). 4. Assessment of Adult Dogs & Cats with an Unknown Vaccination History Clientele who have adopted an adult dog/cat that has no known vaccine history may elect to avoid vaccination if a protective level of immunity can be determined serologically. 5. Antibody Testing in Lieu of Annual Revaccination International guidelines for administration of core vaccines to adult dogs and cats consistently recommend revaccination schedules of no more often than every 3 years for core antigens (CAV-1*/CDV/CPV and FCV/FHV/FPV). However, with regard to rabies vaccination, veterinarians must follow state or local laws. 6. Management of Infection Risk Among Animals Entering a Shelter Immunization status of young animals presented to animal shelters is often unknown. Because the infection risk among shelter-housed dogs and cats is high, determining antibody status of an animal at time of entry allows vaccination and separation (foster) of animals deemed susceptible until a positive test result is obtained. 7. Management of Outbreaks Within an Animal Shelter Antibody test kits offer shelters a management advantage when faced with an infectious disease outbreak involving CDV, CPV, or FPV. Identifying and separating animals with positive (protected) test results from those with negative (susceptible) results may help avoid unnecessary euthanasia. When feasible, susceptible animals should be isolated from the general population, which limits propagation of the outbreak. Isolated, seronegative survivors can be placed or adopted once the incubation period for the infectious agent has passed (2 weeks for CPV and FPV; 6 weeks for CDV). CORE VACCINE ADMINISTRATION & ANTIBODY TESTING • current vaccination guidelines recommend administration of the last dose of core vaccines at 14 to 16 weeks of age in puppies and 16 weeks of age in kittens. • antibody titers may be determined as early as 2 to 4 weeks following completion of initial vaccination series. • a puppy or kitten that is seronegative at 18 weeks of age should be revaccinated not less than 2 weeks following the last dose. antibody testing can then be performed as early as 2 weeks following administration of this last vaccine dose. *All antibody tests detect antibodies against CAV-1; however, the vaccine antigen protects against CAV-2 (a respiratory pathogen), which also cross protects against the more serious, systemic CAV-1 (canine hepatitis virus). May/June 2013 Today's Veterinary Practice 37