5歳5カ月齢のホルスタイン種雌牛が，発熱，食欲不振及び胎盤停滞を呈した．悪露排出及び子宮の腫脹は治療で改善がみられなかった．体表リンパ節の腫大はみられなかったが，直腸検査で子宮の硬結を認めたため，牛白血病を疑った．病理解剖では腹腔内リンパ節の腫大，胃漿膜面の腫瘤形成及び子宮壁の肥厚が認められた．また，組織所見ではこれら組織へのリンパ球様腫瘍細胞の浸潤が認められた．腫瘍細胞はB細胞マーカー陽性であった．牛白血病ウイルス（BLV）抗体は陰性であったが，末梢血のBLVプロウイルス検査では陽性が確認され，本症例におけるBLVの関与が示唆された．A 5-year-5-month old Holstein cow was presented with fever, anorexia, and retained placenta. Postnatal vaginaldischarge and enlargement of the uterus did not improve after treatment. Although the superficial lymphnodes were not enlarged, enzootic bovine leukosis was suspected because of the enlarged and indurated uterus.An autopsy revealed enlargement of most abdominal lymph nodes, tumor mass formation on the omasum andabomasum, and thickening of the uterine wall. Histologically, there were lymphocyte-like cell infiltrates in themicroscopically visible lesions. The tumor cells were immunohistochemically demonstrated to be Bhcells origin.Although antibody against bovine leukosis virus (BLV) was negative, BLV provirus was detected from theperipheral blood. The findings suggested that BLV infection may be related to leukosis in the present case.
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