Paralytic rabies in a goat

Abstract

Background: Paralytic form of rabies is frequent in cattle in Latin America, but it is uncommon in goats. There are few clinical reports on furious rabies affecting goats, and the sporadic cases of rabid goats from surveillance programs worldwide lack clinical data. Furthermore, few studies reported the cerebrospinal fluid findings in rabid livestock.

Case presentation: On a farm in Midwestern Brazil, six of 47 Saanen goats died within one week. No vaccination protocols were implemented on the farm and the owner stated bat bites history on the livestock. Although rabies is endemic in Brazil, livestock vaccination is not mandatory. One 1-year-old buck was evaluated and showed non-specific clinical signs evolving within 12-h to nervous signs. Cerebrospinal fluid analysis revealed mononuclear pleocytosis, hyperproteinemia and high glucose levels. At necropsy, no gross lesions were present. Microscopically, discrete to moderate perivascular lymphoplasmacytic cuffing in gray and white matter, neuronal necrosis, neuronophagia, and mononuclear ganglioneuritis was observed in the brainstem and cervical spinal cord. Immunohistochemistry revealed strong anti-rabies virus immunostaining. Fresh central nervous system samples were positive for rabies in direct fluorescent antibody test (dFAT) and mouse intracerebral inoculation test (MIT). Exposed livestock recommendations included immediate vaccination, a strict isolation period of 90 days, and booster vaccinations during the third and eighth weeks.

Conclusion: IHC revealed the widespread distribution of rabies virus antigen in the goat's CNS, contrasting the discrete pathological changes. In this goat, definitive diagnosis of paralytic rabies was obtained through the association of epidemiological, clinical, laboratorial, pathological findings (histology and IHC) and gold standard confirmatory tests (dFAT and MIT).

Keywords: Central nervous system; Immunohistochemistry; Lyssavirus; Rhabdoviridae; Viral diseases.

Fig. 1

1-year-old Saanen buck presenting depression, somnolence and abnormal standing position

Fig. 2

Goat. a Brainstem. Perivascular lymphoplasmacytic cuffing in white matter (H&E. bar = 100 μm). b Midbrain. Babès’ nodule (arrow) and necrotic neurons (arrow heads) at rostral colliculus (H&E. bar = 50 μm). c Gasser ´s ganglia. Neuronophagia (arrow) and mild mononuclear ganglioneuritis (H&E. bar = 50 μm). d Cerebellum. Anti-rabies virus immunolabeled Purkinje cells with strong reaction of the intracytoplasmic corpuscular structures (Streptavidin-peroxidase, chromogen 3,3-diaminobenzidine. Bar = 25 μm)