Haemophilus somnus-induced Otitis and Meningitis in a Heifer.

The purpose of this report is to describe the lesions of otitis and meningitis associated with Haemophilus somnus infection in a heifer.The animal was found dead in its pen. At necropsy, there was a severe fibrinopurulent meningitis and suppurative otitis media and interna. The external ear canal contained inspissated debris. Haemophilus somnus was recovered in pure culture from the meningeal exudate. The identity of the organism was confirmed by fluorescent antibody and agar gel immunodiffusion tests. Possible pathogenetic mechanisms are discussed.