Multiple apparent Sarcocystis abortion in four bovine herds

Area of Science:

• Veterinary Pathology
• Parasitology
• Reproductive Medicine

Background:

• Multifocal nonsuppurative inflammation, including encephalitis, myocarditis, and hepatitis, was observed in aborted fetuses from four dairy herds.
• Focal placentitis was a common finding in these cases.
• Sarcocystis-like protozoa were identified in the brains of fetuses from two separate outbreaks.

Purpose of the Study:

• To investigate the cause of abortions in dairy herds.
• To identify the protozoan agent responsible for fetal lesions.
• To assess the potential transmission routes and confirm the protozoan identity.

Main Methods:

• Necropsy and histopathological examination of aborted fetuses.
• Identification of protozoa in fetal brain tissue.
• Feeding trials with dogs, cats, and neonatal calves using affected fetal tissues.
• Fecal examination of trial animals for protozoan excretion.

Main Results:

• Aborted fetuses exhibited multifocal nonsuppurative encephalitis, myocarditis, and hepatitis, often with focal placentitis.
• Sarcocystis-like protozoa were detected in fetal brains in two herds.
• Experimental feeding of affected tissues to dogs, cats, and calves did not result in detectable protozoan excretion in feces.
• The exact identity of the protozoa remained unconfirmed.

Conclusions:

• A Sarcocystis-like protozoan infection is suspected as the cause of abortion and fetal lesions in these dairy herds.
• The lack of excretion in experimental animals suggests a complex life cycle or a host-specific limitation.
• Further studies are required to definitively identify the protozoan species and elucidate its transmission cycle.