[Pathology and pathogenesis of ear and brain complications of pasteurellosis in rabbits bred for food].

Naturally occurring seropurulent rhinitis, often associated with bronchopneumonia or pleurisy, was examined by morphological, histological and bacteriological methods on 113 rabbits affected with pasteurellosis. These 63 dead and 50 slaughtered diseased rabbits were from different origins and included a variety of breeds and colours. In a high percentage (80% of cases), rhinitis induced by Pasteurella multocida is associated with seropurulent otitis media or otitis media and interna. Rarely in acute cases or often in chronic cases there is squamous metaplasia of the epithelium of the tympanic bulla and/or of the inner ear. Nervous symptoms like torticollis, falling down on the side or epileptiform fits are seen, in the case of pasteurellosis, only when the inner ear or the regions of the brain responsible for balance are affected. P. multocida can very often (in about 43% of examined cases) be the cause of encephalitis associated with rhinitis, otitis or neuritis. This can be: acute, focal serous or purulent leptomeningitis; serous leptomeningitis associated with focal purulent encephalitis; abscesses in various parts of the brain. In about 70% of examined cases there is neuritis or perineuritis of the trigeminal nerve. These lesions often associated with anatomically localised encephalitis suggest that, in the case of pasteurellosis, the three branches of the trigeminal nerve potentially represent a neurogenic "retrograde and ascendant" path of infection to the brain from nasal cavities, ear or other regions of the head.