Experimental Histoplasmosis, I. Methods for Production of Histoplasmosis in Dogs.

Abstract

The production of histoplasmosis in dogs by respiratory routes of infection has not been previously reported. Yeast-phase Histoplasma capsulatum induced acute, progressive, fatal histoplasmosis in all of 9 dogs when inoculated intratracheally, but no clinical disease in all of 7 receiving the same inoculum by stomach tube. Mycelial phase produced no clinical evidence of infection in 9 out of 10 normal dogs receiving intragastric and intratracheal inoculations, respectively. Cortisone treated dogs, however, were susceptible to intratracheal but not intragastric mycelial phase inoculations. Dogs previously receiving mycelial phase were resistant to reinfection with the same phase even when given cortisone; they succumbed to challenge with intratracheal yeast phase in the absence of cortisone.