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Pork production: More on abortions in your sows

Question: My sow aborted during the weekend. Unfortunately, I only discovered this when I was approaching her pen and noticed she was eating something unusual. It turned out to be an afterbirth. She’d almost finished it and I wasn’t able to examine it or show it to someone who might have been able to tell me why this happened. Why, do you think, did she abort? Is there anything I can do to prevent this from happening again? It would have been her first litter and was due in about 6 weeks.

There are a number of reasons why a sow might abort, and it’s often quite difficult to find out what went wrong. There are both infectious and non-infectious causes of abortion in sows. Those not resulting from infection include feed and temperature related problems.

Also read: Pork production: Getting the basics right for housing


Breeding a gilt (young sow) too young also occasionally results in abortion because, if she’s still growing herself, she might not be able to sustain the pregnancy, particularly if she’s on a diet not high enough in protein. Gilts should not be bred before they are at least 8 months old and they should be close to their adult weight when bred for the first time.


  • Feed-related problems are either not enough feed (the sow will be too thin) or mouldy feed.
  • Some moulds produce poisonous substances that can cause abortions (or stop the sow from becoming pregnant).
  • Dry feed should look and smell fresh, not mouldy, and should be stored in a dry place, off the floor, to avoid dampness.
  • It’s important to clean feed containers well because food sometimes packs down in the corners and becomes mouldy and could be eaten with the fresh food.


  • High temperatures or too little shade can result in abortions.
  • This is more likely in summer but, depending on where you’re farming, winter days can be sunny and too hot for a pregnant sow if there isn’t any shade.
  • Outdoor pigs must have enough shade to be able to be completely out of the sun, and indoor pig housing needs to be well-ventilated to keep the temperature down on hot days.

Also read: Pork production: Protecting your pigs from sunburn


  • Fever resulting from an infectious disease can cause a sow to abort at any time during pregnancy.
  • There are also some infectious diseases that cause abortions by attacking the foetuses or making the uterus unsuitable for their survival.
  • Such diseases usually cause abortions at a particular stage of pregnancy.
  • For example, a disease called leptospirosis causes abortions when the sow is close to her farrowing date.
  • To find out whether the cause of the abortion was infectious, you need to get the help of a veterinarian who will take samples to send to the laboratory.
  • The best sample is the afterbirth, along with the aborted foetuses, but if that isn’t available the veterinarian will probably take a swab of the vagina and perhaps a blood sample.
  • This should be done as soon as possible after the abortion has taken place.

In the case of your sow, if she’s fully grown and in good condition, and doesn’t appear to be ill, she can be bred next time she comes on heat. Provided her food is good quality and her surroundings are comfortable, she’ll probably be able to carry her piglets to term.

If she looks sick or there’s pus coming from the vagina, there’s probably an infection and she should be treated for that and allowed to recover fully before being bred again. Vaccines are available for some of the common infectious causes of abortion in pigs.

  • This article was written by Dr. Mary-Louise Penrith and first appeared in Farming SA.

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