This bacterium is one of the most prevalent abortion-causing agents and is found all around the world (except in Oceania)..
Animals infected by Chlamydia abortus will remain asymptomatic until late pregnancy, usually until up to a month or a month and a half prior to the due date. This is when the abortion or the birth of weak or moribund lambs/kids occurs.
“Abortions caused by Chlamydia abortus: stillborn, weak or moribund lambs/kids”
Unlike other pathogens (Toxoplasma gondii, Border Disease virus, etc.), this type of abortion will always occur at the end of gestation, as of day 110.
“Enzootic Abortion of Ewes: always at the end of gestation”
As of the 90th day of gestation, physiological immunosuppression occurs, and it is at this point that the bacterium invades the placenta, causing the corresponding lesions and resulting in abortion.
Depending on when these lesions occur, stillborn, weak or moribund lambs may be born.
Salmonella enterica subsp. enterica serovar Abortusovis is another important agent responsible for abortions in ewes.
“High prevalence in countries such as Spain, Italy and France”
This bacterium can result in: stillborn, weak or moribund lambs. After abortion, affected ewes often present with fever, depression and anorexia.