Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Paola Dall’Ara

Associate Professor of Veterinary Immunology and Infectious Diseases of Dogs and Cats
Department of Veterinary Medicine and Animal Sciences, University of Milan, Italy

General Introduction:

Canine adenovirus (CAV), canine parvovirus (CPV) and canine distemper Virus (CDV) are recognized as important causes of illness and death in dogs. Puppies are most susceptible to CAV, CPV and CDV, especially after weaning when protective maternally derived antibody (MDA) levels decrease. In many countries, vaccination programs have significantly curtailed, but not eliminated the incidence of these diseases.



Vaccines against Canine Parvovirus type 2 (CPV-2), Canine Distemper Virus (CDV), and Canine Adenovirus (CAdV-1) are classified as core vaccines and are highly recommended for all dogs. Vaccination guidelines suggest vaccinating adult dogs no more frequently than every 3 years using modified live vaccines (MLV), thus obtaining a long-lasting specific protection in many but not all animals. Several factors can interfere with the mounting of an adequate immune protection; therefore, antibody titration would help to reduce both vaccination failures, unnecessary vaccination, and identify older dogs that are no longer protected. In this regard, assessing the actual immune status of each dog using simple in-practice kits is gaining momentum in the world of pet veterinarians.


The aim of the study was to determine the actual levels of seroprotective antibodies against CPV-2, CDV and CAdV-1 in a cohort of Italian dogs by measuring specific protective antibody titers with the help of the rapid Kit VacciCheck.


A total of 1,027 canine serum/plasma samples from vaccinated (951), and unvaccinated (76) dogs were assayed using the in-clinic test Canine VacciCheck and analyzed for Protective Antibody and Titers (PATs) against CPV-2, CDV, and CAdV-1. Differences related to sex, age, breed size, health status, and time elapsed since last vaccination were evaluated.

Results reading

The antibody concentration is defined by the color intensity of the resulting spots of the rapid test and is compared with the “S” units on a scale from 1 to 6. An “S” value of 3 (S3) was standardized to be the equivalent of 1:80 for CPV-2, 1:32 for CDV, and 1:16 for CAdV-1. Antibody titers equal to or higher than S3 values were considered indicative of a significant positive response. Results were divided into unprotected (S0-S1), weak positive (S2), medium positive(S3), and high positive(S4-S6) based on the threshold values of each pathogen. Medium to high positive results were expressed as Protective Antibody Titers (PATs).



Half of the entire canine cohort (50.6%) had PATs for all three viruses. In particular, 90.8% of dogs were protected against CPV-2, 68.6% against CDV, and 79.8% against CAdV-1. Protection lasted for at least 3 years after vaccination.

The percentage increased from 50.6% to 68.5% when titers just below the threshold values (weak positive) were also considered (in accordance with WSAVA’s guidelines).


Revaccination on a 3-year basis, as suggested by the international vaccination guidelines and experts, can be recommended for these diseases without altering neither individual’s protection nor the indispensable herd immunity.

Dr. Paola Dall’Ara