Built in Pregnancy Indicator
One of the questions I get a lot is how to tell if a pig is pregnant. Well, first, is it female? You think I jest but I had a government official who was here once looking at our big boar Archimedes and said, “My what a big sow!” Yes, well… she was a little sheltered, perhaps – The Department of Agriculture officials need to get out more.
So, once you’ve made sure it is female, how do you tell if your pig is pregnant? Well the first thing I do is look at the pregnancy indicator built into the back end of every female pig.
No, this is not piggy porn. What you’re looking at in the photo above is the clitoral hood of a gilt, that is to say a female pig who has not yet had a litter. This gilt’s pregnancy indicator is pointing up. Thus she is pregnant.
In fact, in her case she is very pregnant and nearing the end of her gestation term which is about 114 days (three months, three weeks, three days or so). If you look under her belly you can see that her breasts, her udder and teats, are beginning to fill out and cone up. She will farrow, that is to say, deliver her littler of piglets this coming week out in our south pastures.
In a non-pregnant gilt or sow the tip of the hood would be pointing downward or straight out, the latter the tendency in older sows. This effect is the first thing we see when a pig becomes pregnant. Later there are other signs as she progresses through her gestation.
It is important to know the lady in question before evaluating her pregnancy status since you’ll want to know what she normally looks like. Gilts tend to have downward pointing clitoral hoods since they have not yet had a litter of piglets. As they have litters there is some stretching of the feminine tissues back there which will cause gradual changes and loosening such that by the time she has had eight or ten litters her hood may well be level when she is not pregnant. Not to worry and don’t mention it to her. She’s still beautiful, right? It’s just a sign of her great fecundity – appreciate her but take it into account when evaluating her pregnancy status.
FAQ: Walter when does the “visual” sign of pregnancy that you mention on the website show for a pregnant gilt?
It is going to depend on the gilt, her condition and how many embryos are implanting and thus how much she starts to grow in the uterus. I spot them as early as a few weeks. But, this requires knowing quite intimately the normal anatomy of the ladies since it is not an absolute but rather a change that you’re looking for.
It was an old farmer by the name of Archie who first alerted me to the “pointy thing” as he put it. He didn’t know why but had observed over his 30 years of pig raising that it told him a lady was in that piggy way as he put it. I add about another decade of observation to confirm his note.
Through reasoning and then dissection for confirmation what I have found is that the effect is caused by:
- Lady becomes pregnant – how is a discussion for another time if you are not familiar with these dynamics;
- Uterus begins to enlarge as the walls thicken and fills with fluid and a lot of developing but tiny fetuses;
- Uterus sags down in belly hanging from connective tissue and pulls downward on vagina;
- Vagina pulls down on external genitalia (e.g., vulva) pulling inward the entrance to the vagina just a little;
- Clitoral hood is beyond the fulcrum at the front point of the mons pubis so as the point of the clitoral hood is pulled upward – simple leverage; and finally
- Farmer Walter walks by and looks at her vulva and thinks to himself, “ah, good” giving her a scratch behind the ears.
As the lady nears her farrowing time her vulva will swell as the tissue prepares to pass piglets. This typically causes the clitoral hood to then point back down right before birthing. By this time her bag should be fully developed and she may well be producing milk.
Sows do change over time as they have litters and get stretched out and there are individual differences. This is more of a relative indicator than absolute. Know your pig parts.
There are all sorts of expensive high-tech gadgets you can buy which do ultra-sound and the like to detect pregnancy. In my experience with around a thousand pig pregnancies I have found this method to be a highly accurate at detecting pregnancy in pigs. Keep It Simple. I’ve never had one of my pig pregnancy indicators break down and they don’t require electricity. They’re also inexpensive – they come built in with each female pig. Sorry but male pigs do not have pregnancy indicators. If you’re not sure of the difference between males and females then please check this post and this post about essential differences. The first of that pair also shows an example of a non-pregnant gilt for comparison with the pregnant gilt’s photo at the top.
Update: Some subsequent thoughts based on decades of using this with hundreds of sows as well as talking with other people who it worked for or didn’t work for… The clitoralhood works very well for me but as a funny side thought I may have inadvertently selected for sows that show their pregnancy status this way since I’ve been using this method for decades – Selective pressure creating a little bit of unintended evolution here on our farm, perhaps. On the other hand, all sows I have bought in over the years have clearly shown this too – an argument against selective pressure causing this. Reading it is also a skill. Lastly, at the end of pregnancy as the sow approaches farrowing the tip points back down as the vulva loosens and swells. That could also cause confusion. Studying the vulvas of a lot of ladies – purely educational…
This method, unlike the ultra-expensive ultra-sound imaging machinery, does not tell you how many piglets are there but I would not suggest counting your piglets before they’re weaned. By then they’ll be easy to count and if you have a lot you can use this method.
Note that this does not work the same way in humans due to structural and postural difference between sows and women. Fortunately in pig society it is considered perfectly polite to investigate someone’s butt. However, I would very much suggest suggest that you don’t go walking down the street looking at ladies of non-swine species like this as you might get in trouble.
See In a Piggy Way for another picture of a pregnant gilt a little further along.
I do not do pregnancy diagnostics over email so please don’t send photos of your vulva. The pregnancy diagnostic is really something where you need to know the lady in question before being able to consider if her private piggy parts indicate pregnant or open. As explained, this changes with age. It also varies with breed. It can also give a false indication if she just ate a lot and is feeling rather full – never caller her fat, just fine. The best thing to do is watch for change in your gilt or sow and get to know her normal indicator positions. Then observe the change after mating.
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