The protozoa have recently been found to be carried by dogs and probably coyotes. The dogs transmit the protozoal eggs or oocyts in their feces. Eating the dog feces with the oocyts i nfects cows. Once the cows becomes infected, they pass the infections on to the fetuses they are carrying through the placenta. The fetus is usually autolyzed.
Most infections occur by transplacental infections from infected cows to their calves in utero.
These result in sporadic but continuing abortions within dairy herds. The occasional abortion storms result from massive infections from ingestion of infec tive dog feces. Diagnosis can be made from distinctive brain and heart lesions in aborted fetus or blood titers in cows. Prevention of abortions involves restriction of dogs on dairies from the stored feed and feeding areas. Seropositive cows will continue to have se ropositive calves.