Canine Distemper Virus (CDV)
Canine distemper virus can infect many species including domestic dogs, wolves, coyotes, foxes, ferrets, skunks, and raccoons. Although relatively unstable in the environment, the wide host range and worldwide disease distribution allow for increased risk of virus exposure for free-roaming dogs.
CDV vaccines are considered core vaccines, recommended for all dogs regardless of geographical location. CDV vaccines contain modified-live virus (MLV), high-titer, low-passage (less attenuated) modified-live virus, or a (recombinant) canarypox vector with targeted CDV genes. The minimum age to begin the primary vaccination protocol in puppies is 6–8 wk. MLV vaccines can be blocked, however, by maternally derived antibodies (MDA) against CDV, which decline exponentially over time and are usually absent by 12–14 wk of age. Revaccination is therefore recommended at 2 to 4 wk intervals until greater than 16 wk old; 18–20 wk of age may be preferred particularly in areas of high CDV risk.
After the primary puppy series of vaccinations, a booster should be administered within 1 yr. Thereafter, interval boosters every 3 yr are recommended; annual boosters are not necessary. Longer (>3 yr) duration of immunity after vaccination has been suggested11 but is largely unsubstantiated in the peer-reviewed literature.
Detection of CDV antibodies after vaccination can be performed by hemagglutination inhibition (HI), virus neutralization (VN), or enzyme-linked immunosorbent assay (ELISA). (See the guidelines section on Utilization and Interpretation of Serologic Titers).