Owners should think very seriously before deciding to breed from their pets.  More pigs mean more expense, more space requirements, more waste matter to dispose of and, especially, what are you going to do with the extra piglets?  Do you want to sell them, keep them or give them away, and have new owners been found beforehand?  These matters all require very careful consideration before you start to breed more litters.


Points about breeding

All domestic female pigs can breed about twice every year.

Breeding Vietnamese Pot Belly females will start their first cycle or heat period (which means that they will accept the boar for mating) at about four months of age and will continue to cycle regularly every 21 days for very many years. 

Vietnamese Pot Belly boars are ready to begin breeding at about four months of age.  Miss understanding this most basics of biology have lead to massive increase in the pig population of a household creating serious welfare problem for both the pigs and their owners.

Over population that just started with three pigs – rapidly became a herd of over 60

The uncontrolled breeding of these pigs resulted in atrocious welfare conditions and abandonment by the owners


It is not always very easy to recognize ‘cycling’ in individual female pigs that are kept on their own, so a boar is usually needed to highlight the physiological signs of willingness or readiness of the female to be mated. These signs are:


The sow may be more alert, her ears may be ‘pricked’ (erect), her voice may be pitched higher, she may carry bedding in her mouth, she may squeal, she may go off her food, but especially, very soon after showing signs of heat, she will stand very firmly and be unwilling to move when her owner leans on her back.  This ‘standing position’ is perhaps the best way of telling when a female pig is ready for mating.  Some of the white breeds of pigs may, with their first heat only, show reddening of the vulva (the outside part of the female reproductive organs), which also may be a little swollen and moist. 

Some sows will change their normal pleasant behaviour during oestrus to a very aggressive animal.  This can be very alarming and serious particularly for children.  If this occurs spaying may be the only option.


The period of heat will last for about 24-36 hours-but this will vary depending on the time of year and the nearness of the boar (smell, touch, hearing and sight of the boar will always intensify the signs of heart in the sow.)



If a family of pigs is kept together, then there should be no need for any help by the owner with mating.  However, if the male and female are kept apart, then the owner may have to give some assistance.  If a boar is available, then the sow should be mated twice, with a 24-hour interval between matings.  If a boar is not available and the sow has to be artificially inseminated, then semen must be ordered at the first sign of heat (good record keeping will also help to predict this date) and there must be two inseminations spaced about twelve hours apart, with the first one being made between 12 and 24 hours after the onset of heat, which is as soon as the female adopts the ‘standing for service’ position.  Always make sure that plenty of time is allowed both for natural mating and artificial insemination.  Too much of a hurry will inevitably result in a failure to achieve pregnancy.  If any problems occur at any stage of the mating process then call your vet. 


Owners who don’t want their pet sows to become pregnant:

Have the sow sterilized between 4-6 months of age.

Have the boar sterilized as early as possible.  At 10 days of age is ideal otherwise with anaesthesia at about 4-6 months of age.

Don’t keep a boar.


If left as a group mating will occur from 4 months of age resulting in an explosion of the population

Some owners prefer to have their pet sows sterilized even though they don’t have a boar because when the sow has a heat period she often forgets her toilet training and this will cause problems in the house.


Assuming that the pregnancy was intended

Observe the sow or gilt and determine when she comes into heat.  This can be difficult without a boar.  However, one determined, the sow or gilt will come back into heat in 21 days (18-24).  At this heat keep the sow and boar separate.  Each day put the sow into the boar’s pen, for at least 20 minutes.  When the sow stands readily allow the boar to mate.  Once mating is finished, normally 10-20 minutes later, remove the sow and return her quietly to her pen or paddock.  The next day put the two back together and allow mating to happen again.  If you carry out artificial insemination, mating the sow in the presence of a boar.


After the double mating the sow must not be stressed for the next 28 days.  It is possible to pregnancy check the sow after 24 days using ultrasound examinations.


Pregnancy will last 112-120 days (normally about 115 days – 3 months, 3 weeks and 3 days).


Precautions to take when your pet sow has piglets

When the babies are due, your pet sow will usually make a nest and she will usually be very active for the final 1 or 2 days. Provide the sow with plenty of dry clean straw to enable her to make an adequate environment for her piglets.  Just before delivery begins the sow will settle down by her nest, she may refuse food, but water must always be available.  Imminent signs of giving birth include milk in the teats, a relaxed areas of skin around and below the tail and, of course, straining.  When the piglets are being born the sow’s tail will wag as the piglets pass through her pelvis and her uppermost hind leg may be drawn forward during straining.  Generally the piglets are born about 15 minutes apart or sometimes there is a rush, with several of them being born almost at once.  Because of the small size of the piglets, they can be born front-end or tail-end first and delivery problems very rarely occur; if they do then you must call your vet immediately.  Once farrowing has finished, a ‘bag-like’ after-birth will be passed by the sow and this really indicated that the birth process has ended.  Apart from checking that all the baby piglets are breathing well, have been rubbed dry with a towel and are sucking, nothing further needs doing to them as the sow will now take care of all their needs.  One work of caution: sows with newly born litters can be very protective and will defend them very vigorously – so take care – disturb mother and piglets as little as possible.  Once the novelty has passed, many sows will allow their piglets to be picked up and handled, but always be on your guard.  Once the piglets have been born they need to be put into an area next to the sow where the air temperature is not less than 29oC.  This temperature must be kept for at least 7 days, after which it can gradually be reduced to normal room temperature of 21oC.  If the sow has made a good nest, she while will be able to provide this temperature it may be best to provide a ‘creep’ area to reduce the chance of overlaying by the sow.



This will take place at about 6-8 weeks of age, although some people like the piglets to wean themselves which may not be complete until 12 weeks. You must be careful that the sow does not lose too much weight or too much calcium during a prolonged lactation period.  When the piglets are eating solid food and mum’s milk supply is decreasing, then the piglets can be removed, weaned and housed on their own.    While the sow is lactating well she will not come into heat.  However, once she is weaned, she will normally cycle in heat within a week.



Pet pigs may undergo surgery.  The most common reason for surgery is associated with castration in the male and spaying in the female.  A sow may require a caesarian section at the point of farrowing.  As pigs age, tumors become more common and pigs may need to undergo surgery to remove these tumors.

Basic reproductive anatomy



General anatomy of the female reproductive tract. 

1 Vulva. 2 Urethral opening. 3 Vagina. 4 Cervix. 5 Uterine body. 6 Uterine horn. 7 Oviduct. 8 Infundibulum. 9 Ovary.





General anatomy of the male reproductive tract superimposed on the outside of the pig

General anatomy of the male reproductive tract dissected

Detail of the testes of the male pig