This time of year, the last thing cattle producers want to find when checking cows is an aborted fetus.
Bob Larson, Kansas State University veterinarian, says there are multiple potential causes for abortion. Neospora is a common infectious cause of abortion, transmitted both vertically (from mother to fetus) and horizontally (via feed contaminated by canine feces). Other possibilities include viral diseases, such as IBR or BVD, and feed-related issues like moldy hay or listeria.
Larson and fellow K-State veterinarian Brad White recently discussed a case on the “Bovine Science with BCI” podcast in which a rancher with a couple hundred cows found an aborted fetus in their pasture. The producer wanted to know what to do next.
Larson and White suggest these seven steps when finding an aborted fetus:
1. Gather initial information
- Identify which animal aborted. This includes determining age and status in herd: heifer or mature cow, new addition or long-term member.
- Look for physical signs like retained placentas.
“One of my first questions is I’ve got to kind of figure out who, who is aborting, as in, what kind of describes the animal that’s aborting age? Is it a new addition to the herd? Is it’s a cow that’s been in the herd a long time? Those are the types of questions,” Larson explains.
White says it is important to investigate the fetus to try to determine fetal age.
In the case presented, the rancher says no one was claiming the fetus and they could not determine the mother.
2. Collect samples promptly
- Recover the aborted fetus and, if possible, the placenta, as both provide crucial diagnostic tissue.
- Collect a range of fetal tissues: lung, liver, kidney, brain, and consider additional fluids such as abomasal and follicular fluid.
- Store fresh and fixed samples or freeze if not sending immediately.
Larson says collecting the aborted fetus (and placenta, if available) for diagnostic sampling is essential. The placenta is considered a highly valuable diagnostic tissue, but various tissues from the fetus (lung, liver, kidney, brain, etc.) can also be analyzed.
He suggests samples should be collected and stored (e.g., frozen) after first finding the first abortion but not necessarily sent to a lab immediately. If additional abortions occur, the value of sending samples for diagnosis increases.
The value of testing and taking action also increases with more cases.
“Hold on submitting samples for testing after the first abortion — consider sending if a second or third case occurs,” Larson says. “A single abortion may not signal a herd problem.”
3. Assess the herd environment and feeding practices
Understand what the cows are eating — hay, silage or supplements — and any recent changes or feed quality concerns like moldy hay or exposure to silage.
4. Interpret sampling results and rule-outs
If diagnostic testing is performed, interpret both positive and negative findings in the context of herd health and history.
Larson explains detecting Neospora in the fetus increases suspicion but does not confirm it as the immediate cause of the abortion; context and other risk factors must be considered. A negative result for Neospora lowers its likelihood as the cause.
5. Monitor for additional cases
Observe the herd closely. Larson stresses monitoring for additional cases is important.
6. Review herd management and biosecurity
- Evaluate animal movement in and out of the herd, introduction of new cattle and biosecurity protocols.
- Plan possible future interventions based on patterns or risk factors identified.
Long-term recommendations center on reviewing herd biosecurity, feeding practices and potential exposure risks. Identifying the signalment (age, breed, source) of affected animals helps target preventive measures.
7. Act based on findings and herd impact
- Avoid unnecessary interventions unless cluster or patterns emerge. This includes palpating the herd or collecting serology.
- Record findings and actions.
- Consult with veterinary diagnostic labs or experts as needed.
Larson stresses immediate aggressive intervention is unlikely to affect the outcome of an ongoing abortion event, but understanding causes aids in future prevention and management.
“I can’t really think of a situation where having information today would change the outcome,” Larson says in response to getting in the entire herd and palpating after finding one fetus.
White summarizes these steps help ensure a logical, evidence-based approach to diagnosing and managing cattle abortions.
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