Immunohistochemical study of rabies virus within the central nervous system of domestic and wildlife species.
Authors: Stein L T, Rech R R, Harrison L, Brown C C
Journal: Veterinary pathology
Summary
# Editorial Summary: Rabies Virus Detection in the Equine and Other Species' Nervous Systems Rabies diagnosis relies on identifying viral antigen within the central nervous system, but the distribution of lyssavirus varies significantly between species, potentially affecting diagnostic accuracy when full brain sampling isn't possible. Stein and colleagues applied immunohistochemical staining to archival tissue from 39 confirmed rabies cases across 13 species (including 4 horses, 6 cattle, 3 dogs and 4 cats) to map where viral antigen concentrates in key brain regions—brainstem, cerebellum, hippocampus and cerebrum. Critically for equine practitioners, horses showed optimal viral antigen detection in the cervical spinal cord and adjacent brainstem, differing markedly from dogs and cats (where the hippocampus is the preferred site) and cattle (where the brainstem predominates). Wildlife reservoir species such as raccoons and skunks demonstrated widely dispersed viral labelling throughout the brain, suggesting sampling location matters less for these hosts. Where complete neurological sampling is impractical, this species-specific anatomical guidance should improve diagnostic sensitivity; the immunohistochemical method itself proved reliable across all 39 cases and works with routine formalin-fixed tissues, offering a practical supplement to traditional fluorescent antibody testing when rabies is suspected.
Read the full abstract on PubMed
Practical Takeaways
- •If submitting equine brain tissue for rabies diagnosis, prioritize sampling cervical spinal cord and brainstem rather than other regions to maximize detection probability
- •Immunohistochemistry on formalin-fixed tissues is a reliable diagnostic technique for confirming rabies when fluorescent antibody testing is unavailable
- •Species-specific sampling site selection improves diagnostic accuracy when complete composite sampling is not feasible due to practical constraints
Key Findings
- •Immunohistochemistry successfully detected lyssavirus antigen in all 39 rabies cases across 13 species
- •Optimal detection sites varied by species: hippocampus for dogs and cats, brainstem for cattle, cervical spinal cord and brainstem for horses
- •In horses, cervical spinal cord and adjacent brainstem provided best virus detection compared to other brain regions
- •Wildlife reservoir species (raccoons, skunks) showed widely dispersed viral antigen throughout brain regions