402 



BIOLOGY OF THE LABORATORY MOUSE 



In other subacute cases, the picture is that of a hbrinopurulent synovitis 

 with extension of the inflammation into surrounding structures. Organ- 

 isms may be visuahzed in thrombi and inflammatory foci as pleomorphic 

 bacilli, filaments, etc. In chronic cases, walled-off necrosis, proliferation of 

 cartilage, or granulations and adhesions may replace the destroyed tissues. 

 Organisms are found extracellularly and within the cytoplasm of large 



Fig. 156. — Infection with Strep- 

 tobacillus moniliformis. Three 

 bulbous swellings of tail shown in 

 mouse on left; normal mouse on 

 right. {From van Rooyen.) 



Fig. 157. — Infection 

 with Streptohacillus monil- 

 iformis. Mouse showing 

 moist coat, occlusion of 

 palpebral fissure, and par- 

 alysis of hind legs. 

 {From van Rooyen.) 



mononuclear cells. Cultures of blood, organs, and articular fluid yield the 

 organism even in the most chronic cases. 



The mode of transmission of the spontaneous disease is not clear. 

 Spread by contact and cohabitation presumably occurs, and bites of infected 

 animals probably transfer the infection. Although organisms may be 

 present in the urine, infection does not appear to be transmitted by con- 

 tamination of food or water and all attempts to infect animals experi- 

 mentally by the enteral route have failed (198, 152). Similar but non- 

 pathogenic organisms may be found in the lungs of normal animals and in 

 the dust of hay and straw (112). 



