Interpreting antibody test results
Core vaccines & antibody testing
1. Does a “positive” antibody test result correlate with protection against canine distemper, parvovirus and adenovirus-2 (CDV-CPV-CAV2)?
The only true test of protective immunity involves challenging the patient with the virulent pathogen and assessing the clinical outcome.
That said, a “positive” antibody test result (CDV-CPV-CAV2) generally does correlate well with protective (sterile) immunity in dogs. This applies to not only laboratory-based testing procedures (quantitative testing) but to in-clinic point-of-care (qualitative testing) antibody kits as well. 111,114,115,118,119
2. Does a “negative” antibody test result correlate with susceptibility to canine distemper, parvovirus and adenovirus-2 (CDV-CPV-CAV2)?
Not necessarily. A dog that has previously been vaccinated (core vaccine) may have a “negative” test result after several years if revaccination or natural exposure has not occurred.
However, if challenged, immune “memory” is likely to result in a rapid, anamnestic (boosting) response at the time of exposure. In this case, the patient with negative serology is still protected.9,118
On the other hand, a young dog that tests “negative” 2 to 4 wk following completion of the initial vaccine series should be considered susceptible and revaccinated.
Noncore vaccines & antibody testing
3. Does a “positive” antibody test result correlate with protection?
Not consistently. Vaccines listed in these Guidelines as Noncore vaccines (B. bronchiseptica, canine parainfluenza, Borrelia burgdorferi (canine Lyme disease), Leptospira spp., and canine influenza) do not produce sterilizing immunity (i.e., prevention of infection following exposure). The antibody response following vaccination tends to be short-lived and generally does not correlate with protection.
4. Does a “negative” antibody test result correlate with susceptibility?
Not consistently. Antibody testing for non-core vaccine-preventable diseases (such as leptospirosis and canine Lyme disease) is generally used in the clinical setting to establish a diagnosis of infection (“positive” antibody test result in the clinically ill patient).
A “negative” test result does not predict susceptibility to nor absence of infection.
Indications for testing
5. What are the most common indications for assessing the antibody response to vaccination (CDV-CPV-CAV2)?
In this iteration of the AAHA Canine Vaccination Guidelines, 12 testing indications have been identified. Recommended actions depending on the test results (“positive” or “negative”) have been included for each of the 12 indications.
Interestingly, recent practitioner surveys indicate that “owner request” is the most common reason for performing antibody testing in practice.
Other common indications include: testing to assess the response following completion of the initial vaccine series, testing in lieu of revaccinating a dog that has a chronic or systemic illness, and testing in lieu of revaccinating a dog that has a history of a prior (known or suspected) vaccine adverse reaction. (See the Section on ANTIBODY TESTING.)
Frequency of testing
6. How often should titer testing for DAP be performed?
The frequency of antibody testing should be based on clinical judgement, but it is reasonable to perform antibody testing at least as often as the interval for booster vaccination.