Abortion DiagnosisDiagnosis of Agricultural Animal Abortion
Maintenance of a profitable livestock industry depends upon efficient animal reproduction. Diseases that interrupt pregnancy are very costly, and control measures cannot be devised until the cause for the reproductive loss is accurately identified. However, identifying the cause for abortion in agricultural animals is a diagnostic challenge for clinicians and laboratory diagnosticians alike. The efficiency of diagnosing abortions in laboratories around the world varies widely, at best 30-40% of fetal submissions result in a successful abortion diagnosis.
- abortion results from an event that occurred weeks to months earlier, and the cause is not present at the time of abortion.
- the fetus is often retained for days or weeks after death and is expelled in a state of advanced postmortem autolysis, making lesion identification difficult.
- the placenta, which often harbors valuable diagnostic information, is often not available for examination.
- toxic, nutritional, hormonal, and genetic causes of abortion are often not detectable in fetal tissues.
Despite the above limitations, abortion diagnosis can be attained by knowledge of herd husbandry (primarily nutrition and environment), thorough sampling for laboratory examination, and utilization of current laboratory technology, such as PCR and immunohistochemistry, which can greatly aid the accuracy and rapidity of diagnosis. However, the cornerstone of consistent abortion diagnosis will continue to be close cooperation among livestock managers, clinicians, and laboratory diagnosticians to uncover all clues that may lead to a specific diagnosis.
The basis for bovine and ovine abortion is diverse and includes genetic, thermal, nutritional, toxic and infectious causes. By far the greatest proportion of diagnosed abortions fall into the infectious disease category, and recent technological advances in laboratory diagnosis are heavily biased toward identification of infectious agents. Because of the importance of either “ruling in” or ruling out” infectious causes of abortion, the linked guidelines will focus primarily upon investigation, sampling, and laboratory examination to identify infectious abortifacient agents.