Granulomatous inflammation in retropharyngeal lymph nodes of wild cervids in Saskatchewan.

A portion of retropharyngeal lymph nodes from 6,824 wild cervids, comprising 1,458 white-tailed deer (Odocoileus virginianus), 5,345 mule deer (Odocoileus hemionus), 11 unidentified deer (Odocoileus spp.), and 10 elk (Cervus elaphus), were examined histologically for evidence of inflammation. Focal granulomatous lymphadenitis was detected in 0.3% of white-tailed deer, 1.3% of mule deer, and in one of 10 elk. Material consistent with Splendore-Hoeppli phenomenon was present in 70 (93%) of 75 cases of lymphadenitis. Replicate sections stained with Gram, acid fast, and methenamine silver stains were examined for organisms. Organisms morphologically consistent with Actinomyces spp. were found in one white-tailed deer; no organisms were detected in any of the other cases of lymphadenitis. Aerobic and anaerobic culture from frozen tissue from the lymph nodes was negative, as was polymerase chain reaction (PCR) for Mycobacterium spp. and Mycobacterium bovis. The method of sampling likely underestimated the prevalence of lymphadenitis.