Development of hydrometra in a ewe flock after ultrasonography for determination of pregnancy

Hydrometra was diagnosed in 41 of 1,411 (2.9%) Rambouillet and crossbred Rambouillet-Booroola Merino range ewes that were being examined with ultrasonography for pregnancy. Most diagnoses of hydrometra (40 of 41) were made at a second examination of 581 of the 1,411 ewes 40 days after the first examination (6.9%). Some of the ewes had membranes or small placentomes evident in the uterine fluid, suggesting that there had been embryonic resorption. Of the 15 ewes with hydrometra that were examined ultrasonographically a third time after an additional 42 days, 14 had resolved the condition. The increased prevalence of hydrometra at the second examination suggested that the stress of the first examination may have been a factor. Ovine fetal loss has been documented via ultrasonography, but hydrometra has not been commonly observed. Hydrometra may have developed because of unique circumstances of this flock, or it may be a condition that goes largely undiagnosed because most ewes are not examined for pregnancy twice within a short period.