Comparing Rabies Antibody Titres in Imported Dogs to a Population of Dogs in Ontario, Canada.

Abstract

Introduction: Vaccinating dogs against rabies virus is essential for protecting animal and public health. Most dogs imported into Canada must have a valid rabies vaccination certificate but do not require serological testing to confirm response to vaccination. The objective of this study was to determine the proportion of dogs with rabies antibody titres below 0.5 IU/mL in a sample of imported dogs with rabies certificates, compared to rabies antibody titres in nonimported dogs in Ontario, Canada.

Methods: Serum was collected from a convenience sample of dogs imported via rescues to Ontario, within a month of arrival and before revaccination with rabies in Canada. Rabies antibody titres were measured using the rapid fluorescent foci inhibition test (RFFIT) at Kansas State University's Rabies Laboratory. Univariable logistic analysis examined demographic, vaccine and country of origin factors associated with achieving a titre of at least 0.5 IU/mL. Rabies antibody titres from nonimported dogs were obtained from the University of Guelph's Animal Health Laboratory records. Dogs tested between 2013 and 2023, using either the RFFIT or fluorescent antibody virus neutralisation (FAVN) test, were included.

Results: From October 2021 to November 2022, serum was collected from 67 dogs arriving mainly from Egypt (n = 46). In total, 48% (32/67) of these dogs had titres below 0.5 IU/mL, and this included 19 dogs that had no measurable titre. No examined factors were significantly associated with the outcome. Of the 65 nonimported dogs, 14% (9/65) had titres below 0.5 IU/mL.

Conclusions: Rabies titres of many imported dogs were below the international standard for transboundary movement. A high proportion of dogs with unmeasurable antibodies suggests some had not been effectively vaccinated. Veterinarians should be aware of this gap and consider revaccinating imported dogs to protect both animal and public health, and to meet legal requirements of their jurisdiction. Rescues and owners should be informed that documentation does not always guarantee imported dogs have adequately responded to vaccination and to seek veterinary advice.