Objective—To evaluate postexposure prophylaxis
(PEP) in dogs experimentally infected with rabies.
Procedure—Dogs were sedated and inoculated in
the right masseter muscle with a salivary gland
homogenate from a naturally infected rabid dog (day
0). Six hours later, 5 dogs were treated by administration
of 2 murine anti-rabies glycoprotein monoclonal
antibodies (mAb) and commercial vaccine; 5 received
mAb alone; 5 received purified, heat-treated, equine
rabies immune globulin (PHT-ERIG) and vaccine; 5
received PHT-ERIG alone; 4 received vaccine alone;
and 5 control dogs were not treated. The mAb or PHTERIG
was administered at the site of rabies virus inoculation.
Additional vaccine doses for groups mAb plus
vaccine, PHT-ERIG plus vaccine, and vaccine alone
were administered IM in the right hind limb on days
3, 7, 14, and 35.
Results—All control dogs and dogs that received only
vaccine developed rabies. In the PHT-ERIG and vaccine
group, 2 of 5 dogs were protected, whereas
none were protected with PHT-ERIG alone. Use of
mAb alone resulted in protection in 4 of 5 dogs.
Administration of mAb in combination with vaccine
provided protection in all 5 dogs.
Conclusions and Clinical Relevance—Current
national guidelines recommend euthanasia or a 6-
month quarantine for unvaccinated animals exposed
to rabies. Findings from this study document that vaccine
alone following severe exposure was unable to
provide protection from rabies. However, vaccine
combined with mAb resulted in protection in all treated
dogs, revealing the potential use of mAb in PEP
against rabies in naïve dogs. (Am J Vet Res
CASE DESCRIPTION A female alpaca, kept at pasture with 12 other female alpacas, 2 crias, and 5 goats, was evaluated because of clinical signs of aggression.
CLINICAL FINDINGS The clinical signs of aggression progressed to include biting at other animals as well as disorientation. Three days later, the alpaca was euthanized because of suspicion of rabies virus infection.
TREATMENT AND OUTCOME No physical injuries were found at necropsy. Brain tissue specimens were confirmed positive for rabies on the basis of direct fluorescent antibody test results. Molecular typing identified the rabies virus variant as one that is enzootic in raccoons. The farm was placed under quarantine, restricting movement of animals on and off the property for 6 months. To prevent further rabies cases, 14 alpacas (12 adults and 2 crias) were vaccinated by extralabel use of a large animal rabies vaccine. Of the 14 vaccinated alpacas, 8 had paired serum samples obtained immediately before and 21 days after vaccination; all 8 alpacas had adequate serum antirabies antibody production in response to rabies vaccination. As a result of an adequate serologic response, the quarantine was reduced to 3 months. In the year after the index rabies case, no other animals on the farm developed rabies.
CLINICAL RELEVANCE Extralabel use of rabies vaccines in camelids was used in the face of a public health investigation. This report provides an example of handling of a rabies case for future public health investigations, which will undoubtedly need to develop ad-hoc rabies vaccination recommendations on the basis of the unique characteristics of the event.