The bacillus of glanders may be so modified in virulence as to produce experimentally lesions differing widely in their histological features.
The highly virulent culture causes primary necrosis and disintegration of the tissue followed by the invasion of the injured area by polymorphonuclear leucocytes. The bacilli of moderate virulence give rise to a primary lesion of an acute inflammatory nature in which the cells show no evidence of necrosis or disintegration. The attenuated bacilli produce primary tissue proliferation with the formation of epithelioid and giant cells.
There is every grade of lesion between the acute exudative and the chronic proliferative depending upon the toxicity of the cultures.
The glanders lesion whether exudative or proliferative is focal in character.
The strong toxins of the glanders bacilli cause degeneration or necrosis of cells and exudation, while the dilute and weak toxins produce proliferation.
The giant cell of glanders undoubtedly originates from the endothelial cell of the blood and lymph channels and is formed by division of the nucleus of the endothelial cell and not by cell fusion.
Histologically the lesion of glanders resulting from the culture of a low degree of virulence is proliferative and is analogous to tuberculosis; the lesions are focal and bear an intimate relation to the glanders bacillus.