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United States Department of Agriculture

Agricultural Research Service

Title: Exposure of Sero-Positive Gilts to Swine Influenza Virus As a Possible Factor Causing a Few Stillbirths Per Litter

item Wesley, Ronald

Submitted to: Canadian Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 17, 2003
Publication Date: July 1, 2004
Citation: Wesley, R.D. 2004. Exposure of sero-positive gilts to swine influenza virus may cause a few stillbirths per litter. Canadian Journal of Veterinary Research. 68(3):215-217.

Interpretive Summary: Pathogens of the porcine respiratory disease complex, including viral pathogens like swine influenza virus (SIV), cause pneumonia in pigs which is the industry's most costly disease. Stillborn piglets result from infectious and non-infectious causes and they are the most important cause of preweaning mortality. This research addresses aspects of both problems. In this trial 3 pregnant dams were exposed to SIV at the beginning of the third trimester and 3 matched, pregnant dams were used as controls. Each of the 3 litters from the SIV-exposed dams suffered 2 or 3 stillborn piglets per litter while the matched, control dams had no stillborn piglets. Thus, there was a statistically significant association between SIV exposure in the dam and increased stillborn piglets in the dam's litter. This research may help to reduce the number of stillborn piglets which would benefit swine producers and veterinarians.

Technical Abstract: Six naturally infected, pregnant gilts, sero-positive for SIV subtype H3N2, and perhaps, infected around breeding time, were used in this experiment. Near the end of their second trimester at 80 - 82 days of gestation, 3 of the gilts were experimentally exposed to SIV subtype H3N2. No clinical signs resulted from this exposure and HI titers of the SIV exposed gilts at day 27 post-exposure suggested that the gilts had not been re infected. However, observations at farrowing indicated that the experimental exposure to SIV had an effect on the number of pigs born alive. Each of the 3 litters from the exposed gilts suffered 2 or 3 stillborn piglets/litter whereas the matched, sero-positive control gilts had no stillborn piglets. These differences were statistically significant by the Chi-square test (P < 0.01). Sera from 2 of the stillborns were negative for HI antibodies and there was no indication from the pigs born alive that the H3N2 virus had crossed the placenta.

Last Modified: 4/19/2015
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