Submitted to: Veterinary Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/18/1999
Publication Date: N/A
Citation: Interpretive Summary: Neospora caninum is a single celled parasite of livestock and companion animals. It is a major cause of abortion in dairy cattle. Until recently, transplacental transmission was the only known mode of its transmission. Recently, a resistant stage of the parasite (oocyst) was discovered in dog feces. Little is known of the role of the oocysts in the epidemiology of bovine neosporosis. Scientists at the Beltsville Agricultural Research Center and the University of Maryland-Virginia College of Veterinary Medicine found oocysts in feces of dogs fed infected mouse tissues and confirmed the hypothesis that the oocyst is an important part of the Neospora life cycle. These results will be of interest to veterinarians, parasitologists, dairy people and biologists.
Technical Abstract: Two mixed breed dogs were fed mouse brains containing tissue cysts of the NC-beef strain of Neospora caninum. Both dogs excreted N. caninum oocysts in their feces. Dog 1 was given methylprednisolone acetate (MPA) prior to ingesting tissue cysts. This dog excreted oocysts with a prepatent period of 5 days and excreted oocysts on days 5 to 10 and on day 17 after ingesting tissue cysts. Dog 1 had a serum antibody titer of 1:200 in the indirect fluorescent antibody test (IFAT) 35 days after it was fed tissue cysts. Dog 2 was not treated with MPA excreted oocysts on days 6 and day 9 after ingesting tissue cysts. Antibodies to N. caninum were not found in a 1:25 dilution of serum on any examination period for Dog 2 during the study. Neospora caninum was not found in the tissues of either dog when they were examined at necropsy 42 days after ingesting tissue cysts. The identity of the oocysts excreted in the feces of the dogs was confirmed by mouse inoculation studies.