From May to June 2006, asymptomatic abortions occurred successively in the mid-pregnancy sows in a 10,000-pig breeding farm in Yangchun City, Guangdong Province. After epidemiological investigations, clinical diagnoses, and laboratory tests, it was diagnosed as a miscarriage caused by chlamydia. Through the addition of chlortetracycline, enhanced cooling ventilation, humidity control and a series of comprehensive measures, the condition has been effectively controlled. The summary is as follows:
Epidemiological Investigation
There were no asymptomatic abortions in the sows before the pregnancy before May, and asymptomatic abortions occurred from May to June, with a cumulative total of 18 (of which 15 were early and 3 were mid-term). The sows that suffered a miscarriage were all located in the middle row of positioning columns, showing scattered distribution, but the positioning bars on both sides of the eaves did not occur. The scene found that the positioning bar is wet and poorly hygienic. The aborted sow is lying in the excreta. The thermometer shows a temperature of 30°C-31°C in the column. Fans on both sides of the eaves have been turned on, but no fan is installed in the middle row of positioning bars. , obviously boring.
Clinical symptoms
Abortion sows have more severe tear spots, eye conjunctivitis, conjunctival hyperemia, increased dark circles around the eyes, and sows who suffered miscarriage are mostly in the pre-pregnancy period. The incidence of miscarriage in the second trimester is relatively small. The sows’ intake and body temperature did not show any abnormalities; the bloodstream of the sow in the aborted sow had traces of residual blood, and the fluid products were scattered on the surface of the stool or in the middle of the stool. They were pink or dark red jelly-like, and some showed fetal shape.
Two kinds of abortion sows that dissected two severe fissure hoofs found that endometrial edema, hyperemia, and necrosis in the intima. In addition, inguinal lymphadenopathy, pulmonary hemorrhoids and hematoma, the lung surface distribution of a lot of bleeding and bleeding spots, lung tissue texture hardening, trachea, bronchial secretions.
Laboratory testing
The serum samples from 11 aborted sows were collected. The results showed that the infection rate of chlamydia was higher, of which 6 were positive, accounting for 54.5%; 2 were suspicious, accounting for 18.2%; 3 were negative, accounting for 27.3%.
According to epidemiological investigations, clinical manifestations, pathological necropsy, and laboratory tests, it was confirmed that the sow abortion was caused by chlamydial infection.
Prevention
1. Strengthen disinfection: Spray 2% caustic soda solution + 5% quicklime water in the inside and outside of the pig house twice a week, and disinfect once immediately after the rain. During the onset of illness, spray disinfection with quaternary ammonium salts, chlorine preparations, or acid disinfectants is used every day at the highest temperature. In particular, the positioning bar should be used as a key disinfection area.
2. Strengthen ventilation and reduce heat stress: Install fans in a middle row of positioning bars in time, install a fan every 10 columns, and fan ventilation at room temperature over 27°C to reduce the impact of heat stress on the herd.
3, to strengthen the humidity control: rainy days lime in several aisles to absorb moisture; usually try to reduce the rush bar, if the ground is dirty can choose to be sunny or the highest temperature during the day; timely removal of water, dung, accumulation urine ; Don't put too much water in the trough, put 1/3 of the trough can prevent sows from playing in the water.
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