Abortion in cattle is a major reproductive issue that impacts herd productivity, farm profitability, and animal welfare. It can occur due to infectious agents (viruses, bacteria, protozoa, and fungi) as well as non-infectious causes such as nutritional deficiencies, toxins, and stress. Understanding the underlying causes, clinical signs, diagnostic approaches, and prevention strategies is essential for veterinarians, farmers, and livestock handlers.
This article provides a comprehensive review of the pathogens responsible for abortion in cattle, their transmission, clinical effects, diagnostic methods, and control measures. Additionally, we discuss zoonotic risks diseases that can spread from cattle to humans—and best practices for minimising outbreaks.
1. Viral Causes of Abortion in Cattle
Bovine Viral Diarrhea (BVDV)
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Causative Agent: Pestivirus (BVDV-1 & BVDV-2).
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Transmission: Direct contact, contaminated feed, or transplacental infection (leading to persistently infected calves).
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Abortion Timing: 2–6 months gestation.
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Clinical Signs: Weak calves, congenital defects, mucosal disease.
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Diagnosis: PCR, virus isolation, ELISA.
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Prevention: Vaccination, biosecurity, culling PI (persistently infected) animals.
Infectious Bovine Rhinotracheitis (IBR, BHV-1)
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Causative Agent: Bovine herpesvirus-1.
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Transmission: Respiratory droplets, venereal (semen), or reactivation from latent infection.
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Abortion Timing: 4–6 months gestation.
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Clinical Signs: Respiratory distress, “red nose,” necrotic placentitis.
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Diagnosis: PCR, serology, histopathology.
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Prevention: Modified-live or killed vaccines, quarantine of new animals.
Bluetongue Virus (BTV)
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Transmission: Biting midges (Culicoides spp.).
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Abortion Timing: 2–6 months gestation.
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Clinical Signs: Fever, oral ulcers, fetal mummification.
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Diagnosis: RT-PCR, virus neutralization test.
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Prevention: Vector control (insecticides, housing management).
Rift Valley Fever (RVF)
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Zoonotic Risk: High (causes severe flu-like illness in humans).
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Transmission: Mosquitoes, direct contact with infected tissues.
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Abortion Timing: Any stage (1–9 months).
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Clinical Signs: Hemorrhagic fever, high mortality in calves.
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Diagnosis: RT-PCR, IgM ELISA.
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Prevention: Vaccination (in endemic areas), mosquito control.
2. Bacterial Causes of Abortion in Cattle
Brucellosis (Brucella abortus)
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Zoonotic Risk: High (causes undulant fever in humans).
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Transmission: Ingestion of contaminated placenta, milk, or aborted fetuses.
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Abortion Timing: Late gestation (7–9 months).
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Clinical Signs: Retained placenta, weak calves, infertility.
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Diagnosis: Rose Bengal test, PCR, culture.
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Prevention: Test-and-slaughter programs, RB51 vaccination (where legal).
Leptospirosis (Leptospira spp.)
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Zoonotic Risk: Yes (causes Weil’s disease in humans).
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Transmission: Contaminated water, urine, or placental fluids.
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Abortion Timing: Any stage (1–9 months).
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Clinical Signs: Hemoglobinuria (“redwater”), stillbirths.
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Diagnosis: Microscopic agglutination test (MAT), PCR.
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Prevention: Vaccination (multivalent lepto vaccines), rodent control.
Listeriosis (Listeria monocytogenes)
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Zoonotic Risk: Yes (causes meningitis in humans).
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Transmission: Silage contamination, poor-quality feed.
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Abortion Timing: Late gestation (7–9 months).
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Clinical Signs: Neurological signs (circling disease), septicemia.
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Diagnosis: Bacterial culture, PCR.
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Prevention: Proper silage management, avoid moldy feed.
Campylobacteriosis (Campylobacter fetus subsp. venerealis)
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Transmission: Venereal (bulls act as carriers).
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Abortion Timing: 5–9 months gestation.
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Clinical Signs: Early embryonic death, repeat breeding.
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Diagnosis: Culture from vaginal mucus, PCR.
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Prevention: AI (artificial insemination) with tested semen, bull vaccination.
Summarise Table of Cattle Abortion
3. Protozoal and Fungal Causes of Abortion in Cattle
Neosporosis (Neospora caninum)
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Transmission: Dogs (definitive host) shed oocysts in feces.
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Abortion Timing: Any stage (1–9 months).
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Clinical Signs: Repeated abortions, congenital infection in calves.
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Diagnosis: Serology (IFAT, ELISA), histopathology.
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Prevention: Limit dog access to cattle feed, cull infected cows.
Toxoplasmosis (Toxoplasma gondii)
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Zoonotic Risk: Yes (risk to pregnant human).
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Transmission: Cat feces, contaminated feed.
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Abortion Timing: Any stage (1–9 months).
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Clinical Signs: Mummified fetuses, weak neonates.
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Diagnosis: PCR, serology.
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Prevention: Rodent and cat control, proper feed storage.
Fungal Abortions (Aspergillus, Mortierella)
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Transmission: Moldy feed, contaminated bedding.
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Abortion Timing: Any stage (1–9 months).
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Clinical Signs: Thickened placenta, stillbirths.
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Diagnosis: Fungal culture, placental histopathology.
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Prevention: Dry feed storage, avoid spoiled silage.
4. Non-Infectious Causes of Abortion in Cattle
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Nutritional Deficiencies: Vitamin A, selenium, iodine.
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Toxins: Nitrates, mycotoxins, poisonous plants (e.g., pine needles).
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Stress: Heat stress, transportation, rough handling.
5. Diagnosis and Control Strategies
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Diagnostic Workup:
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Submit aborted fetus & placenta for necropsy, PCR, histopathology.
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Serological testing of the dam.
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Control Measures:
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Biosecurity: Quarantine new animals, restrict wildlife access.
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Vaccination: IBR, BVD, Leptospirosis, Brucellosis (where applicable).
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Herd Management: Proper nutrition, stress reduction, hygiene.
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Conclusion
Abortion in cattle has diverse causes, requiring a systematic diagnostic approach. Farmers and veterinarians must prioritize vaccination, biosecurity, and proper herd management to minimize losses. Additionally, awareness of zoonotic risks (e.g., Brucellosis, Leptospirosis) ensures both cattle and human health protection. By implementing these strategies, producers can enhance reproductive success and herd sustainability.
