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)

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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. 

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 carrying 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.

Bovine leucosis in a pregnant uterus

Keywords: BLV, cow, bovine, leucosis, pregnant, vagina

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Enzootic bovine leucosis is a result of infection by bovine leukemia virus (BLV). Less than 1% of all the cattle infected with this virus actually develop lymphoid sarcomas and often these are found in pregnant cows. In this case, where the cow was approximately 5 months pregnant, the vagina was affected (black arrows) as well as the myometrium (yellow and green arrows). The double ended green arrow shows a diffuse area of the myometrium thickened by a sarcoma.

Leucosis in the uterus of a cow

Keywords: bovine, COD, cystic, BLV, leucosis, uterus, bovine

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Bovine leucosis is caused by the bovine leukemia virus (BLV). Many cows are carriers and asymptomatic. In this case, as shown by the arrows, there are multiple foci of leucosis in the uterus of the cow. This cow also had a cystic CL,in the right ovary; a normal structure in many cycling cows (not to be confused with a luteinized cyst).

Leucosis in the uterus of a pregnant cow

Keywords: leucosis, bovine, neoplasia, BLV, pregnant

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Leucosis seen in the dorsal wall of the body of the uterus in a pregnant cow. This tract was obtained from a slaughter  plant specimen, so no history as available other than the cow being labeled as a "cull cow". It was estimated that this pregnancy was approximately 45 days old. It is not a usual to encounter pregnancies in cattle that are severely affected by leucosis, even when the uterus is involved.

Lymphosarcoma pyometra in a cow

Keywords: lymphosarcoma, pyometra, cow, unusual, BLV, leucosis, bovine, uterus, pus

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An unusual form of pyometra in a cow. Usually, pyometra in cows is due to infection with Arcanobacter pyogenes during the postpartum period. In this case, pyometra was due to bovine leukosis caused by the bovine leukemia virus (BLV). Usually, cows with leucosis in the uterus have multiple nodular disseminated foci of lymphosarcoma; occasionally, large plaques of lymphosarcoma in the myometrium. In this case, there were no typical modules of lymphosarcoma in the uterus. Instead there was a large volume of pus in the uterus, composed entirely of lymphocytes. As is usual, the cow also had disseminated leucosis nodules throughout many of its organs; the spinal canal, heart, liver etc.