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Abortions are one of the most frustrating disease conditions to work with from the diagnostician's perspective. Serious attempts to determine causes of abortions however must be made to reduce the risk of further losses in the herd. Abortions are different from stillborn or calves that have been lost at birth. Abortions by definition are an interruption of the pregnancy before it is been completed. Calving losses during the delivery process may be due to an infectious or toxic substance, but more likely are due to managerial influences. Dystocia or calving difficulty often is due to large birth weight calves being gestated by heifers with small pelvic openings. Abortions, on the other hand are often due to infectious disease or intake of a toxic compound by the pregnant cow. Identifying the cause of the abortions and preventing further loss must take a high priority in the cow calf operation. Some abortions occur due to accidents of nature. However, if more than one is noticed in the herd, it is probably wise to visit with your local veterinarian to begin the process of diagnosing the cause. Producers must act rapidly to ensure the best opportunity for success in the diagnosis procedure. Samples are often in poor condition because of the extended time between fetal death and expulsion from the uterus. For animals on pasture, predator damage to the fetus may also hinder diagnostic procedures. Typically, diagnosticians in veterinary diagnostic laboratories across the United States find a cause for abortion in only 25% to 30% of cases. But this statistic is misleading since the laboratory results do help veterinarians and producers rule out other causes of abortion in the herd. Table 1 lists the samples required to complete a diagnostic evaluation in cases of abortion. When fetuses are available for postmortem examination, samples should be selected from stillborn animals or mummified fetuses separately, depending on the differential diagnoses. At times, submitting an intact fetus or a number of aborted animals is feasible. If at all possible, do not freeze the fetuses. Freezing creates architectural artifacts in tissues that are already extremely friable and often decomposed because of death in utero. These changes can impede gross and microscopic examinations and lesion identification as well as disrupt infections particles and antigen presentation in tissues, limiting the use of many diagnostic tests. In addition, submitting placentas and fetuses encrusted with dirt and bedding typically yields few results because of overgrowth of contaminant organisms, although these samples may be of benefit for microscopic studies. Remove excess organic and contaminating materials by rinsing the samples before sending them to the laboratory. Diagnosing abortion by serologic (blood) testing of affected animals alone seldom provides a definitive diagnosis. Serologic profiling is most effective. Samples from affected individuals and random samples from herdmates or animals in adjacent areas are required to identify reproductive pathogens cycling through the herd, unit, pen, or group. Individual paired serum samples from an animal that has aborted rarely reveals causal pathogens. Serum samples should be centrifuged, separated from the clot, placed in clean leak-proof containers, legibly identified, and shipped refrigerated. Table 1. Samples Needed for Abortion Diagnosis Fresh tissues and other samples for bacteriologic and virologic examination
Formalin-fixed tissues for histopathologic and immunohistochemical
evaluation
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