Experimental syphilis and serological examination for treponematosis in hares

Of 202 captive hares studied, many of which had lesions on their external genital organs or testicular atrophy or both, 27% had positive serological tests for syphilis although dark-field examination of extracts of atrophic testes was negative. A total of 12 hares that were nonreactive for the serological test for syphilis was inoculated with Treponema pallidum, 9 intratesticularly and 3 intradermally. Six of the animals inoculated intratesticularly exhibited orchitis after 7 days with an associated accumulation of treponemes. No chancres developed in the intracutaneously inoculated animals during a 27-day period of observation. These results provide additional evidence to support the contention that endemic treponematosis occurs in wild hares and suggest that hares are moderately resistant to experimental infection with T. pallidum.