Distemper, infectious canine hepatitis and parvovirus are life-threatening diseases due respectively to canine distemper virus (CDV), canine adenovirus virus (CAV)-1 and canine parvovirus (CPV). The maintenance of the serological response post-vaccination is often used to evaluate the protective status of a dog. However, as live vaccines stimulate mainly the cell-mediated pathway of the immune system, this method may underestimate the real duration of efficacy of these vaccines. The study aim was to evaluate the efficacy of the attenuated CDV, CAV and CPV strains of the multivalent Canigen^TM DHPPi/L vaccine (Virbac, France) after experimental infections performed at three years after the first annual booster.

Forty-seven SPF Beagle puppies, males and females, participated in the study. Puppies were allocated to either the vaccinated group (group 1, n=23) or the unvaccinated group (group 2, n=24). Puppies of group 1 received Canigen^TM DHPPi/L vaccine, formulated at minimum titre for the live components, for primary vaccination with two injections at a three-week interval (respectively at 9 and 12 weeks of age) and for the first annual booster. Blood samples were taken on several occasions for serological followup. CDV, CAV-1, CPV-2 and CPV-2c antibody titres were measured by seroneutralisation tests (SN). After vaccination, SN antibody titre ≥10^0.7 for both CDV and CAV-1 and ≥10^1.17 for CPV-2 variants are considered as positive. At three years after the first annual booster, dogs of both groups were administered either a pathogenic CDV (n=10) or CAV-1 (n=12) or CPV-2c (n=12) strain and followed for the appearance of any typical sign of the related disease for 21 days. Vaccinated dogs with the lowest SN titres were selected to receive the pathogenic agents.

In group 1, 23/23 puppies seroconverted after the primary vaccination course. At 3 years after the first annual booster, SN antibodies against CAV-1, CPV-2 and CPV-2c were still present in 23/23 dogs and in 21/23 dogs for CDV. After the experimental infections, typical signs of distemper and infectious hepatitis leading to death were observed respectively in 5/5 and 6/6 non-vaccinated dogs and in none of the vaccinated dogs (respectively n=0/5, n=0/6). Typical signs of parvovirus including CPV viral shedding were observed only in the non-vaccinated dogs.

In conclusion, this experimental study demonstrated that the protection against distemper, infectious canine hepatitis and parvovirus lasts at least three years after any annual vaccination booster with Canigen^TM DHPPi/L vaccine.

Disclosures

Disclosures to report
All authors are employees of Virbac.