Rabies antibody titres in vaccinated dogs

In a field study, rabies virus neutralizing antibody titres were determined by the microtest modification of the rapid fluorescent focus inhibition test before and after primary vaccination in 30 puppies, and before and after booster vaccination in 59 previously vaccinated dogs. A commercial modified live virus vaccine was used. Three weeks after primary vaccination the mean antibody titre was 102 +/- 90, but only 24 dogs presented for booster vaccination had detectable antibody levels (mean titre 12 +/- 16). The antibody responses three weeks after booster vaccination (mean 380 +/- 216) were significantly greater than the responses to primary vaccination. It was concluded that previously vaccinated dogs could have an anamnestic response to booster vaccination, even when antibodies were not detected in their sera before revaccination.