Bone marrow hypoplasia in a feminized dog with an interstitial cell tumor.

Bone marrow hypoplasia and feminization developed in a 10-year-old male German Shepherd Dog with interstitial cell tumor. Clinical abnormalities included pyrexia, pale mucous membranes, signs of abdominal pain, large left testis, atrophied right testis, and feminization. Abnormal laboratory findings included pancytopenia, bacteremia, bacteriuria, and pyuria. Results of cytologic examination of a bone marrow aspirate were consistent with aplastic anemia. Serum estradiol concentration was high, and serum testosterone concentration was low, compared with normal values for male dogs. The left testicular mass was identified as an interstitial cell tumor. Other causes of the aplastic anemia or feminization were not found.