Feline Infectious Peritonitis
Infection is usually oral although respiratory and transplacental transmission have been described. Outcome of coronavirus infection depends largely on the particular strain of virus involved and the ability of the cat to mount a strong cell mediated immune response. Following inf ection macrophage / monocyte associated viraemia then develops with dissemination of the virus around the body. These activated monocytes and the cytokines they produce are central in the development of the multisystemic vasculitis (phlebitis) and pyogranulomatous inflammation typical of this disease.
Central nervous system pathology is characterised by a fibrinous and pyogranulomatous periventriculitis with the exudate sometimes resulting in the occlusion of the mesencephalic aqueduct between the third and fourth ventricles (arrows), resulting in internal hydrocephalus. Other CNS lesions which have been documented include meningitis, leucoencephalitis, segmental myelitis and choroiditis.