Several factors can cause a stillbirth. Among the causes are various infectious agents, including bovine viral diarrhea virus, leptospirosis, and neosporosis; plant and chemical toxins; and physical injury. The reason for stillbirth and abortion are notably hard to diagnose, even when excellent diagnostic specimens are obtained. For that reason, the cause of the occasional stillborn or aborted calf may not be worth pursuing. Repeated stillbirths or abortions should be investigated by working with a veterinarian to assure that all appropriate diagnostic samples are submitted to a veterinary diagnostic laboratory.
Vaccines help protect against a few of the agents that cause these losses. Vaccine protection is not complete. Infections may still take place and abortions may still occur in vaccinated cattle.
