A pregnant bovine uterus with leucosis
Keywords: leucosis, uterus, bovine, cow, pregnant, BLV
A uterus was examined from a six year old Holstein cow after two lactations; pregnant for a third time. The cow had been losing weight, her milk production had diminished unexpectedly and she had begun to show ataxia. Not being a valuable asset to the herd, she was culled and submitted for postmortem examination.
The cow had been bred 54 days before the date of culling. Interestingly, a highly experienced bovine practitioner had palpated her uterus transrectally shortly before breeding and found it to be apparently normal. Yet, approximately 60 days later, the same practitioner reported that uterus was both rigid and thick-walled. As shown below, ultrasonography revealed a grossly thickened uterine wall and a live fetus with a normal heart rate (~ 190bpm).
(Ultrasonographic image copyright: Dr B. Crane. AVC)
Image size: 574 x 435px
This finding suggested that the neoplastic process had developed very rapidly; a common finding in leucosis.
(Ultrasonographic image copyright: Dr B. Crane. AVC)
Image size: 574 x 435px
This finding suggested that the neoplastic process had developed very rapidly; a common finding in leucosis.
Based on histopathology, lymphomatous masses were present in numerous locations including internal lymph nodes, kidneys, the right atrium, the abomasum and in the spinal epidural space. The subdural lesions probably accounted for ataxia exhibited by the cow. Findings in the uterus are shown below.
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There was diffuse but variable thickening of the myometrium with lymphomas, creating a friable uterine wall that developed fissure lines where it was manipulated. There were also several lymphoma nodules in the vagina. Surprisingly, the 54 day old fetus and its membranes were not autolysed, indicating that the fetus had probably survived until the time of euthanasia of the dam.
There was diffuse but variable thickening of the myometrium with lymphomas, creating a friable uterine wall that developed fissure lines where it was manipulated. There were also several lymphoma nodules in the vagina. Surprisingly, the 54 day old fetus and its membranes were not autolysed, indicating that the fetus had probably survived until the time of euthanasia of the dam.
Notes: There are several forms of lymphosarcoma in cattle but only one form has a known etiology i.e. bovine leucosis, caused by the bovine leucosis retrovirus (BLV). Bovine leucosis is not considered to be a common cause of abortion, probably because so few animals that are carry BLV actually become symptomatic. However, as is evident from this case, leucosis does have the potential to cause abortion in cattle.
Transfer of BLV is usually vertical and must occur by cell transfer, therefore events such as calving, surgical intervention, dehorning and even transrectal palpation have been incriminated. However, recent data has shown that transrectal palpation may not be as significant in the transmission of leucosis as once believed.
No vaccine is available for the control of bovine leucosis so control is often exercised by culling of test-positive animals. Fortunately, BLV is not transmitted during embryo transfer. Therefore embryos from BLV positive cows can safely be transferred to BLV negative surrogate heifers.
