Studies on dermatophytosis in dogs. III. An experimental study on some factors for establishment of infection with Microsporum gypseum of soil origin.

Abstract

It is generally accepted that Microsporum gypseum infection in animals isoriginated from soil. As far as the author knows, however, no experimental studies haveever been reported to prove it. Some experiments were performed in order to elucidatehow the soil served as a source of M. gypseum infection in dogs. The soil of a place fromwhich this fungus had been isolated was rubbed into the skin of dogs, but no infectionwas established. When soil mixed with numerous spores obtained from the culture ofthis fungus was used as an inoculum, the fungal infection appeared at the site of inocula-tion. When kept on soil mixed with spores of M. gypseum for 2 months (May and June), no dogs contracted infection from the soil. When 5 dogs were kept on soil mixed withfungal spores and horse hair for 2 months (July and August), lesions of ringworm causedby this fungus were produced in three of them. From these results the following explana-tion was given for the M. gypseum infection originated from soil. Dogs were not easilyinfected with this fungus inhabiting the soil. Nevertheless, the presence of hair shedfrom dogs and environmental conditions during summer made it easy for the fungus tomultiply in the soil and infect dogs kept on the soil. Therefore, spontaneous cases ofM. gypseum infection were found in autumn, when Resigns produced in summer becameapparent.