Suppurative otitis of the albino rat.

Abstract

It has been observed in colonies of albino rats that certain individuals become affected with a condition characterized chiefly by the following phenomena: The animal persistently holds its head tilted to one side; instead of running in a straight line it does so in a curve in the direction of the deviation of the head; and when suspended by the tail the body spins rapidly around in the same direction. It was also subsequently discovered that deafness on one or both sides accompanies these symptoms. According to private communications this condition has been observed in various breeding stations in this country, and Greenman and Duhring 1 make mention of this condition under the heading of Middle Ear Disease.

The colony under our observation consists of four strains obtained from different sources which will probably be traced to a common strain. The disease has been studied for the past twelve months, and out of 2,700 animals, twenty-three became affected at various periods. Of these, three died, two apparently from the disease, and one as a result of pneumonia. The other twenty did not seem very sick, and outside of the symptoms mentioned behaved like normal rats. Nor did the disease entirely prevent reproduction or raising of the young.

Autopsy of such animals invariably revealed a purulelnt condition of the ear of the affected side, associated with purulent rhinitis, and nothing remarkable in the rest of the organs. Microscopical examination of the affected ear showed the middle ear filled with pus, and osteomyelitis of the auditory bulla (mastoiditis). The inflammatory process could be traced from the middle ear into various structures of the internal ear.