430 BIOLOGY OF THE LABORATORY MOUSE 



spread epidemically (58, 197). Sporadic cases may be recognized by Uic 

 denuded plaques usually present on the head or trunk. The skin in these 

 areas is thickened; and disk-like, whitish-yellow crusts or scales cover the 

 lesions. At the margins, the hair is of poor texture and easily pulled out. 

 Diagnosis may be made by culture of the infected tissue on Sabauraud's 

 agar and by microscopic examination of hairs or scales mounted on slides in 

 10 to 20 per cent sodium or potassium hydroxide solution. After 20 or 30 

 minutes mycelia and spores of the fungus may be seen both inside and out- 

 side the hairs. Various types of fungi have been reported : Achorion quincke- 

 anum, A . Schoenleinii, Trichophyton ectothrix megalosporium, and T. gypseum. 

 Achorion quinckeanum {Sabouraudites quinckeanus, Micros porum quincke- 

 anum) is generally considered to be the common cause of favus of mice. 

 There is considerable disagreement concerning classification of the fungi and 

 identification of the various species is difficult. Details may be found else- 

 where (215, 66, 340, 85). In general, spontaneous recovery occurs but treat- 

 ment can be effected by the application of tincture of iodine, Whitfield's 

 ointment, or a mercurial ointment. Care must be taken in handling 

 infected animals, since the fungi readily infect man. 



DuBois (58) has described an infection with T. gypseum granulatum 

 involving 5 to 9 mice in a single cage. The first 3 animals affected showed 

 an inflammatory type of cutaneous reaction with follicular suppuration. 

 The lesions progressed slowly over the skin, producing complete loss of hair 

 and toxic cachexia resulting in death. No visceral involvement was found 

 at autopsy. The 2 other mice developed only focal areas of involvement 

 without suppuration and recovery took place in 4 weeks. Microscopic 

 examination and cultures of both types of lesions revealed the same organ- 

 isms. Experimental inoculations produced only the attenuated type of 

 infection. 



Parish and Craddock (197) encountered an extensive epidemic of 

 trichophytosis due to T. gypseum aster oides among a breeding stock of 2500 

 mice. The onset was sudden, 400 mice developing signs of the disease 

 within a few days. Although the spread of the disease during the next 

 6 weeks was slow, recrudescence occurred and over 1000 mice of all ages were 

 affected, necessitating destruction of the colony. 



The lesions most frequently were situated on the neck, but were common 

 on the back and rump. They consisted of bald patches with inflammatory 

 thickening and scaliness of the skin. At the margins the hair had lost its 

 luster, was brittle, easily detached, and in the worst cases the entire coat had 



