BACKGROUND: Over the recent years, Neospora caninum has been one of the most important causes of abortion in dairy cattle. OBJECTIVES: We conducted the present study in order to investigate the seroprevalence of N. caninum in dairy cattle in Semnan province and its effect on abortion. METHODS: 237 blood samples were obtained from various Semnan dairy farms and 104 bulk dairy samples from four milk collection centers in Semnan, Garmsar, Damghan, and Shahrood were tested for sera and milk utilizing ELISA (Svanova Biotech AB) test kits. RESULTS: The results revealed that 87.27 % of bovine serum was positive. The percentage of opacity density (OD) of positive sample (PP) ranged from 72.17 to 137.3 (114.21±24.65). In addition, the average rate of milk seroprevalence to the parasite was 95.23 % in Semnan province. CONCLUSIONS: The frequency of Neospora caninum infection in blood and milk was high in Semnan, yet no significant relationships were observed with abortion (p < /em>>0.05).

BACKGROUND: Neosporosis is a disease caused by the protozoan Neospora caninum, which is characterized by abortion in cattle and neuromuscular paralysis of various organs, particularly the hind limbs of dogs. The diagnosis of neosporosis is often made by serological molecular tests.OBJECTIVES: This study was conducted to investigate the presence of N. caninum oocysts in the feces of dogs. METHODS: A total of 100 fecal samples were collected from indoor and outdoor dogs during 2018-2019 around Tabriz. Information about age, location, and history of antiparasitic treatment of the dogs were recorded in a questionnaire. Primarily, fecal samples were examined microscopically for Neospora ocysts. After breaking the collected oocysts through freeze-thaw and sonication, DNA contents of the oocysts were extracted and analyzed via PCR.RESULTS: In a light microscopic study, oocysts were observed in 45 (45 %) of the fecal samples. In the PCR study, 21 of the 45 cases tested positive for Neospora infection (21 %). All the positive cases of infection were observed in molecular examination in dogs older than one year. The positive cases were observed in 2 % of the domestic dogs, 8 % of the stray dogs, 6 % of the kennel dogs, and 5 % of the rural dogs. Furthermore, 19 % of the infected dogs had no history of antiparasitic treatment; only 2% had a history of antiparasitic treatment. The results of statistical analysis showed that the rate of infection in dogs around Tabriz with Neospora caninum was significantly (P<0.05) related to the animal's living environment and history of antiparasitic treatment. However, this rate was found to have no significant relationships with the age of the animals.CONCLUSIONS: Due to the high rate of infection with Neospora caninum in dogs in Tabriz, it is necessary to apply preventive methods in traditional and industrial farms around this city and use rapid diagnosis methods in them.