Abortion in the pig

There are a range of causes of abortion in the pig. Majority of abortions are non-infectious and some 90% are not diagnosed. It is also normal for 1.5% of all services to fail to farrow due to abortion. Abortion can occur at any time of pregnancy after day 11 until day 112. However, it should be noted that the loss of embryo’s around day 20 without the loss of the corpus lutea will not result in abortion, the sow will enter and period of pseudopregnancy and recycle after day 63.

Causes of abortion can be simply divided into four categories. If you have an abortion problem discuss these issues with your veterinarian.

Non infectious causes:
Seasonal Effects
70% of all abortions fall into this category. Remember it is normal for sows to farrow in the spring, and therefore, there is a natural tendency for pregnancies to be lost in the summer and autumn. There are many factors believed to be involved in the summer infertility/autumn abortion syndrome – reduction in light length, effect of heat, loss of appetite in the summer
Environmental abortions
Sows may be subjected to stress factors relating to their environment: draughts, excessive heat stress, inadequate cooling, change in the feeding routines, changes in stockpeople, bullying when introduced into a new group and trauma from moving through narrow doorways. All of these factors singly or combined can result in abortion in the individual sow. Injections can also result in abortions at times	Provide adequate cooling and sun cream
Broken window resulting in draughts	Fighting in sows can lead to abortions

Mycotoxins
Although difficult to prove, mycotoxins have long been suspected as being responsible for abortions. In any case of 2 or 3 abortions over a short period of time, clean out the feed bins and feed lines. Never feed mouldy feed to animals. Mouldy straw can also play a significant role in the causes of abortion			Never feed mouldy feed to pigs. Ensure good feeder hygiene at all times
Check straw for excessive mould	Regularly clean and check feed lines
Infectious causes
There are a range of infectious causes of abortion. Disease agents can cause abortion through one of two major routes: a) luteolysis – generally through a high temperature releasing prostaglandins b) Killing the piglet/placentitis Examples of diseases that cause luteolysis include swine influenza, erysipelas or swine fever. Diseases that kill piglets would include Aujeszky’s Disease or Japanese Encephalomyelitis virus How diseases such as Leptospirosis cause abortion is still unclear.		Aborted foetuses
Porcine Reproductive and Respiratory Syndrome virus
PRRSv can be responsible for severe abortion storms when a new stain enters a niave population of pregnant sows. PCR and sequencing can help identify the source of the new strain. Note however, not all abortion storms on PRRSv positive farms are associated with PRRSv. Note PRRSv cannot infect embryo’s or early fetuses.