Pathologists Urge Using Some Horse Sense to Avoid Doghouse When Making Diagnoses

Abstract

TWO DOMESTIC animal diseases that increasingly are found in humans were the focus of reports at the recent annual meeting in Chicago, Ill, of the United States and Canadian Academy of Pathology. Although still rare, they are growing less so. In one, an immunosuppressed state offers an invitation to an opportunistic pathogen. In the other, no reason for the species leap is yet apparent. Rhodococcus equi (originally called Corynebacterium equi ), a gram-positive, weakly acid-fast coccobacillus that is normally found in horses, has been documented in 39 patients since the first case report in 1967. All but eight of the cases occurred in the United States. At the Chicago meeting, Margie Scott, MD, Department of Pathology, Vanderbilt University Medical Center and the Veterans Administration Medical Center, Nashville, Tenn, reported on eight cases during the last 10 years in which the organism was identified in patients in those institutions. The patients ranged