Sows: Behaviour and female health problems (including ovarian cysts)

[Wiebke]

1 Sexing on arrival
2 Important reproductive Facts
- Start of making babies - seasons - lack of menopause
- Pregnancy
3 Sows in season
- How a season runs
- Strong seasons (snap seasons; the social role of strong seasons; problem seasons)
4 Behaviour and social aspects
- Bonding (Possible combos; acceptance and dating; special bonding aspects)
- Typical sow dominance behaviours (arrival, bonding and group/territory changes)
- Failed bondings, fall-outs and bullying
5 Health issues of the reproductive tract
- Ovarian cysts (types, symptoms and treatment options)
- Other health issues affecting the reproductive tract (by symptoms)


1 Sexing on arrival

Please always, always, always double-check the gender of any guinea pig upon arrival and before any bonding!
Mis-sexing is still sadly very common. This can happen at any stage, from not separating dads and baby boars in time at the breeder's, during transport to a pet shop or at the shop. This means that you can buy an already pregnant shop or breeder sow/

Please use our illustrated guide to re-check the gender. Always check the secondary areas as well (absence/presence of a penis ridge under the skin and presence/absence of a fleshy seal just below the opening of the slit), as they are usually unequivocal on the gender, which the arrangement of the genitalia often isn't. You can be 100% sure if you get the same answer re. absence of a boar penis ridge and presence of a sow flesh seal in sows - or the other way around in boars!
Our illustrated sexing guide will show you exactly where to look and what to look for: Illustrated Sexing Guide
New Guinea Pigs: How to Best Manage Arrival and Settling In


2 Important reproductive facts
It is very important to know our biological facts with guinea pigs as there is still a lot of misunderstanding around, including with many general vets.

At which age start guinea pigs making babies?
Baby boars start making babies themselves between 3-5 weeks of age or even a little bit sooner if they are large and well developed, while sows have their first season at 4-6 weeks (or even a little bit sooner). This coincides basically with the weaning.
Many for sale breeders and many general vets are sadly not aware of the fact that boars can reproduce before they reach sexual maturity when their testicles descend between 4-6 months of age, which is the age generally quoted in veterinary literature.

When and how often do sows come into season?
Sows come into season every 15-17 days (roughly every two weeks). This is called the oestrus cycle (US: estrus cycle).

In the presence of boar pheromones, sows can come into season spontaneously if they are close enough in the oestrus cycle.
That is why play dates, even under your supervision, don't work. Making babies takes only a few seconds and happens too quickly for you to intervene. Boars also have hooks at the tip of their penis to anchor it in case the sow moves away too soon; if you try to rip them off, you can injure them. Boars can only mate if the sow is willing, by the way. Any sows that could be potentially pregnant need to be treated as such until you know for sure otherwise.

Sows come into season again within hours of giving birth. If they are still with a boar when giving birth, you need to put them on a 10 weeks pregnancy watch and take very good care of them as back-to-back pregnancies are very hard on sows and really take it out of them. The risk of complications and miscarriage is also higher.

Please be aware that a newly neutered/de-sexed boar is only 100% safe six weeks after the operation. The little baby in my avatar is the surprise daughter from a supposedly safe over 5 weeks post-op boar (not one of mine), just to prove this particular point! There is a crucial difference between 'mostly safe' and 'totally safe' - and like a lottery win, it can happen to anybody. This recommendation follows best UK welfare practice, by the way, and has stood the test of time.

There is no menopause for either sows or boars
They can make babies all their life long. The older they are, the higher the risk of miscarriage, dead-born babies and the death of the mother during birth or from birthing complications.


Pregnancy
A first pregnancy lasts on average about 10 weeks. This is also the observation period you need to put your sows on if they have had an accidental meeting with a full or too recently neutered boar until you know for sure otherwise.
You won't see generally see anything for about 7-8 weeks on average, depending on the size of the litter (a large litter will become noticeable sooner while a single baby may not show at all), and that is also the time when a vet can confirm a pregnancy reliably with a scan or x-ray.

Please be aware that about every fifth pregnancy ends with the death of either babies and/or mother even on the best of care. This percentage is going up quickly in less than optimal surroundings/ages. This is one of the main reasons why are a strictly no intentional breeding forum.

If you are worried about a pregnancy, please open an ongoing support thread for the whole duration of your pregnancy watch/until you need to separate any male babies in our pregnancy section, which is specially monitored by experienced and trustworthy members with a pregnancy signature.
You are welcome to ask any questions and concerns in your thread for as long as necessary to make sure that your sow and any babies are as well cared for as possible during the whole time. Pregnancy, baby care and sexing (no-breeding)

Please also read our comprehensive pregnancy, diet, birth and baby/mother care advice pack, which has been specially written for people without any previous experience and is as step-by-step and practical as we have been able to make it. The information pack also includes diet advice, hot weather care, baby sexing/separation and practical advice if you also have the dad as well as caring tips for orphans/small babies and baby development information.
Pregnancy & Baby Care Guide's

Our Pregnancy and Baby Care section and our information guides are only visible after you have registered with our forum and have agreed to our strict no intentional breeding policy.
Please note that any advice and support on this forum will only be given with the express aim to prevent any further pregnancies. Anybody found in breach of our very explicit no breeding rules will be summarily banned.
Terms of Service And Forum Rules
Our forum stance on breeding and showing explained: Our non breeding non breed showing forum policy explained

 

[Wiebke]

3 Sows in season

How often do sows come into season?
Sows come into season about every 15-17 days. Most of the time you won't notice it but sometimes they can be very hormonal and dramatic. I have observed that this happens more often with adolescent girls, freshly bonded or introduced sows (whether that is to another sow or a neutered boar) or after an operation that has interfered with the estrus cycle.

Typical behaviours during a season
A sow coming into season can be grumpy or temperamental for a few days (especially if she is the alpha sow).

Over the roughly one and a half day of her season, she will sniff bottoms, rumble, chase and mount her companion as if she were a male. Even when a neutered boar is present, they will chase and mount their female companions or even the boar himself before a sow is ready for mating for only a comparatively small spell at the end of her season.
A sow signals her readiness for mating by hunkering down and lifting her bum; a boar has to be very quick because she won't necessarily stay in that position for long and move off. A boar can only mate with a willing sow; it is the sows who are in control, not the boars.

Sows have a special whine when they are coming into season, but are not quite ready to mate yet. They will stick closely to a boar, whip him into a frenzy but will refuse to actually mate until they are fertile. It can be very dramatic, vocal and loud.

A strong season is a very smelly affair: Boars will spray their testosterone laden pee at the sows to mark them as theirs. Sows will also waft their own female-in-season pheromones (which are the reason for all the bum sniffing) in a boar's face but they will target pee at any boar that is too daring too early or sniffing too persistently. A yellow nose is the equivalent of a ring for a 'husboar' ( a neutered boar living with sows).

The harassed companion of a mounting sow will either kick her off straight away or allow her to hump until she's fed up, all accompanied by lots of squeaking and often a fair bit of kerfuffle! However, things should stay well below the level where fights would threaten. The humped sow will usually make it clear when she's fed up.

Well bonded piggies will often reaffirm their bond with exchanges of affection on the following day.


Strong seasons
Snap seasons
Sows can come into season spontaneously when coming into contact with boar pheromones or the boar themselves if they are close enough to a season in their estrus cycle.
This is the reason why play dates between boars and sows are a total No No. Any meeting with non-group members is a full-on bonding session for guinea pigs; they don't play with each other.
The actual impregnation takes only seconds

The social function of strong seasons
Seasons are also used to cement a group together by the Top Lady of a group having a strong one. The shared experience helps to bind the group closer together, especially during the ca. 2 weeks group establishment phase that follows a bonding introduction; but also after any changes in the group, be it a loss or new additions.
Reacting to group or territorial changes: Dominance and group establishment/re-establishment

The first season with a new 'husboar' is always a strong one. The shared excess of phermones and high emotions helps to gcement the new bond. Less dominant guinea pig dads can take an active interest in bringing up group pups so both sides have a viable investment in a strong relationship, which helps to enhance the survival chances of a group and their offspring. Interestingly, if they are socially minded, boars are not fussed about whose babies they are looking after. Some make very caring and diligent nursery nurses and maintain a life-long affectionate bond with their charges.

It is always the sows who accept the boar and not the other way round; the group (it would have been usually closely related sows) will want a strong male - he who has the most sonorous rumble impresses most. However, a strong Top Lady is not minded to share the lead; she wants to be in control of her group and may prefer a more submissive and socially minded boar.

Sows and even not over-sexed boars will also be generally very patient and supportive if their companion is experiencing a very strong season, especially for the first time. The shared excess of emotions and pheromones can serve to bond them more closely, especially at the start of a relationship.
Here are some videos taken over the course of a strong season, illustrating different stages of it: When Sows Experience A Strong Season (videos)

If you are interested in the social wiring of guinea pigs, you may find this link here interesting: Reacting to group or territorial changes: Dominance and group establishment/re-establishment

Problem seasons: Feuds and hormones
Coming into season can spark a reopening of an unresolved dominance dispute or long running smouldering feud, especially when the under-sow is not happy with the way things are. Sows are really good at holding grudges; once they have decided they don't want another piggy to be a member of their group, they rarely change their opinion until - and never guaranteed - very old age.

If an adult sow seems to be in season nonstop or constantly very aggressive/confrontational as a teenager whenever she is in season, then please see an exotics vet for ovarian cysts or hormonal imbalances. The nonstop seasonal behaviour is not just taking a physical toll on the affected sow (weight loss), it does impact on the whole group and can be especially stressful on under-sows (potential bullying) but it can lead to a group falling apart; especially when two sows having cyst issues at the same time.
Moody Guinea Pigs: Depression, Bullying, Aggression, Stress, Fear and Antisocial Behaviour

How to work out whether a group bond is still viable or not: Bonds In Trouble

 

[Wiebke]

4 Behaviour and social aspects

Bonding considerations
Guinea pigs live in strictly hierarchical groups. Any boar is part of the group hierarchy but not part of the sow hierarchy.
Establishing and sorting our a working hierarchy is therefore vital for any successful bond. The dominance phase, which lasts around 2 weeks after the bonding itself is there to work out the shape of the relationship. This can look very rough but you have to sit out.

Bonding should always happen in a neutral place to prevent the newbies from being seen/feeling as invaders and hostilities/over-reaction happening as a result. Before you start bonding at home, make sure that you have a plan B at the ready (usually next door companionship) in case things don't work out to plan.

Please take the time to carefully read this comprehensive guide here to which the following remarks are only an elaboration but no replacement: Bonding and Interaction: Illustrated social behaviours and bonding dynamics

Possible sow combinations
Sows can be kept in any number with or without a neutered boar in principle.
Our general experience over the last decade is that even numbers in smaller groups tend to work better, as does introducing a pair of not fully grown sows to an older pair instead of a single. A neutered boar can work beautifully if you want to go from two sows to a trio, but it will not prevent an outsider problem if the sows are not good friends in the first place. Small goups are doing best when they can rescue date for any new additions to make sure that the newbies fit in, as they are very much personality driven.

Acceptance issues and dating
Contrary to common perception, by far not all sows will accept a new companion or will happily bond with another guinea pig, whether that is a sow or a neutered boar. Especially sows that are feeling vulnerable in the presence of stange piggies, rebonding new mothers after the end of the nursing period, sows with active ovarian cysts and hormonal imbalances, bereaved sows who have lost their long term companion and older sows past ideal child bearing age can be very picky about who they want to live with!
Very difficult is also bonding two adult sow pairs as most top sows will not want to relinquish their position. Closely bonded pairs are also often not very willing to accept a third, sometimes even a single baby.

Dating single piggies for sows for a neutered rescue boar allows you to test the waters under expert supervision before you bring any new companions or a neutered husboar home. Rehoming sows and neutered boars from a rescue that offers dating also ensures that any new adoptee is fully quarantined/vet cared, properly sexed and guaranteed not pregnant. The adoptees' personalities are known. You also do not pay for the full neutering/spaying operation/vet cost (never mind upkeep while in rescue!) when adopting a de-sexed piggy and you will have the rescue to turn to if the bonding fails at any point in their adoptee's life. Many good standard rescues that in the majority offer dating have de-sexed bachelors and bachelorettes available to enable safer cross gender bonds.
Rescues (Adoption and Dating), Shops, Breeders or Online? - What to consider when getting guinea pigs

Bonding aspects particular to sows
For our detailed bonding advice which looks at both behaviour and dynamics during all stages of bonding from preparation to the end of the post-bonding dominance phase, please see the link below. The following remarks serve only as an addition to it and do not replace it.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics

Full-on fights in sows are comparatively rare. The sow equivalent of a fighting boar bite is a mouth full of hair since sows are wired to live together in a group where inner cohesion is necessary for the survival of the group as a whole. They can get into tussles (especially with a randy boar) but the are usually carefully judged to not cross the line into outright aggression.
Bloody bites or full-on aggression are the signs of a stressed out sow on edge; they are defensive and fear driven in nature. Please separate if you notice a sow being stressed out (stiff body language and no friendly overtures).
A - Z of Guinea Pig Behaviours

Insecure sows will usually hold themselves apart and refuse to interact. The may answer any intrusion into their personal space with lunges. Please abort the bonding; it won't work out.

Sows that will go on the attack without a by your leave right from the word go are thankfully pretry but it means that they feel totally out of their water and are maxed out on their survival instincts. They are generally the result of human action (abuse, neglect, lack of correct or any species socialisation from a young age).
Giving piggies time to get used to each other through the bars before any meeting can minimise the occurrance of extreme overreactions.
Understanding Prey Animal Instincts, Guinea Pig Whispering and Cuddling Tips
Arrival in a home from the perspective of pet shop guinea pigs

If the wrong kind of signals is exchanged, tension can build up extremely quickly and fights can happen seemingly out of nowhere. Have your oven gloves at the ready! This is definitely the end of the road for any bonding attempt. Sows rarely bite deeply into the rump the way fighting boars do; but they can bite full-on onto the mouth if they feel cornered/trapped when they are already very stressed and on edge.
" Biting" And What You Can Do

While not every teeth chattering is necessarily a fail in a bonding, persistent tension and unfriendly exchanges do not bode well. You can interrupt a bonding and resume the next day if the general tension is not coming down, but please be aware that guinea pigs don't bond in 5 minute meetings; they usually need several hours in one go to really work out a hierarchy.
If things are much calmer on the second meeting, then acceptance of the new hierarchy has happened and your piggies want to be together. Any hierarchy establishment always happens from the top down. The worst dominance usually comes from the sow ranked just above; she wants to ensure her own ranking.
However if tensions resume pretty immediately again, the problem has not been solved and is not likely to so even if the bonding as such is not violent. Sows are masters at grudge matches; if there is an underlying issue, they will bring it up again and again and again over the coming years!


Typical sow dominance behaviours
Typical dominance behaviours in the ca. 2 week period (can last short or much longer) after the bonding include rumbling while shifting the weight from one back leg to the other ('rumble-strutting'), teeth chattering, head-butting and nipping (a carefully judged gesture of power that lets the recipient only feel the teeth but not harm it, with the under-sow protesting loudly/squeaking submission) and bullying practices like taking over the hut, food bowl, hay etc. (answering defiant clucking noise), yawning, going chin to chin (pushing their heads up facing each other), chasing, nipping and little scuffles can result. It can look pretty rough to us humans. Don't separate unless there are serious bloody fights or there is no gradual softening of the attitude even after 2-3 days; the piggies NEED to sort out their differences without your interference!

Dominance against babies can look very unpleasant because they are emphatically put at the bottom of any hierarchy (including by their mothers) after they have been weaned. Please keep in mind that most dominance behaviour is much more show than substance - it only hints of the power. Babies are much faster and agile than adults, and they are also very vocal and dramatic, especially when submission screaming (which is NOT pain). As long as you do not have any hideys and corners with just one exit during that phase, babies can always escape easily and won't come to any harm. Ideally you only ever have hideys with two exits in a cage; this cuts massively down on any bullying.

After they have sorted out the terms of their relationship, your piggies will hopefully become more relaxed and friendlier with another.
A - Z of Guinea Pig Behaviours
Reacting to group or territorial changes: Dominance and group establishment/re-establishment


Failed bondings, fall-outs and bullying
A bonding has failed if two sows cannot come to an agreement as to which of them comes top or if there is systematic and persistent bullying of the under-sow that is in resulting in weight-loss/no weight gain in sub-adults or depression/staying away as much as possible from the bullying piggy well beyond the normal dominance phase.
Please be aware that sows can be a lot sneakier, more inventive and underhand about bullying in their interaction with other sows than the more upfront boars. They can also hang onto a grudge or perceived sleight for the rest of their lives.

Any weight loss in sows should be first vet checked for medical reasons, but it in can in some cases be caused by systematic bullying (keeping a sow from accessing food, including hay, and water; 'locking her in' by blocking hut exits or ramps etc.,).
Please make sure by only using hideys with two exits, access to hay by more than one way/offering hay in more than one place, having two water bottles at different ends and serving veg and pellets in smaller amounts that can be eaten in one go in a bowl each that is at least body length apart. Remove the bowls in between meals; this will also encourage your guinea pigs to eat more hay, of which should make over 80% of the daily food intake.

It is also a myth that sows do not fall out. They do, just not as often as boars; but once they have made up their mind that the other piggy is no longer part of their group, then they won't change their mind. Ever! Or at least not for the next five years or may be close to death, whichever comes sooner... Including with a sister they have been living with since birth
(PS: They eventually did join for the last weeks of their lives coming up to 7 years after spending half of it in different groups.)

More information about failing/failed bonds and bullying at any stage during a relationship
Bonds In Trouble
Moody Guinea Pigs: Depression, Bullying, Aggression, Stress, Fear and Antisocial Behaviour

 

[Wiebke]

5 Health issues of the reproductive tract

Here is a list of health problems that are related to the reproductive tract that you should be aware of as a sow owner.
Please be aware that any necessary operations or hormone treatments can run into the hundreds of pounds and dollars and that you save up for any vet cost right from the start as part of the regular feeding and maintenance cost on a monthly or weekly basis.


Ovarian cysts

Wild guinea pig sows (cavia tschudii or montane guinea pigs is the still existing ancestor species living in the Andes) have not been engineered to live for more than ca. 3 years (although a few wild guinea pigs can live to 8 years). They have a distinct breeding season between spring and autumn with 3-4 pregnancies during the time when rich fresh grass is available in abundance. A menopause was therefore biologically not needed.
The domestication of guinea pigs ca. 3000-6000 years ago and the human-driven breeding out of what was a farmed species and is now also our pet guinea pigs (cavia porcellus) have brought some major biological changes: nonstop pregnancies all year round and longer lives without the high hormone output ever stopping. This causes increasing problems in older age. In fact most older sows (an estimated 75-80% of them) have ovarian cysts.

Cysts are not all the same
Please be aware that the majority of cysts don't produce any physical or behavioural symptoms but that they can still grow to a huge size. It is also worth keeping in mind that not all ovarian cysts are hormonal.

- Active hormonal cysts
It is often the smaller cysts that cause the aggressive hormonal behaviour during a growth spurt. Grumpiness, irritable/confrontational behaviour and what looks like a nonstop season (which can lead to a gradual weight loss from the constant stress on the body) are typical for a high hormone output. The behavioural changes are usually a much better give-away than physical symptoms, which often fail to manifest.
Physical symptoms can include crusty nipples (the most common symptom) and much less often balding sides which can extend across the belly and then also spread up the flanks to the shoulders and the back in untreated hormonal cysts.
Hormonal cysts are typically most active during the age of 2-4 years although the very earliest have been found in very hormonal teenagers. 18 months is the usual early onset age and they can carry on into old age.

- 'Silent' fluid-filled large cysts
In fact, the majority of ovarian cysts - which are increasingly present in many older sows - do not present with any hormonal symptoms at all and often go unnoticed. They are generally fluid filled and can grow to quite a large size, which can cause its own problems (gut adherence). Some will however still have enough hormones to react to hormone treatment but others won't.
You can generally spot the the really large one because they look like baby balls sticking out to the sides or the back in guaranteed not pregnant sows. It is worth having a look during your weekly body onceover and weigh-in health and grooming check.
Fluid filled cysts become more common from 4 years onward.

- Cancerous cysts
Unfortunately, a small percentage of ovarian cysts can turn cancerous.
There is a likely genetically driven variety that happens in younger adulthood, around 2-3 years of age. Any bleeding from the anus should be vet checked. It is always serious and can be your only symptom that you may be dealing with a cancerous ovarian cyst.
Any ovarian cysts that are hard to the touch need removing; if they are not cancerous now, they are likely to turn cancerous later on in older age; they are the second group of cancerous cysts.

- Burst cysts and peritonitis
Cysts can unfortunately burst. Sometimes it is not necessarily the biggest ones. Quite often, this is not causing any problems but some can cause peritonitis (infection of the lining of the inner body cavity that contains the gut, the urinary and reproductive tracts). Peritonitis is often fatal.

Possible treatments for ovarian cysts
- Hormone treatments
There are now increasingly hormone treatments (chorulon injections for the UK or hormone implants, which are more commonly used in the US) available as an alternative to a full spaying operation provided the cysts are hormone based (not all ovarian cysts are). However, by far not all vet are willing to use them due to the risk of major side effects. They can however even help to shrink large cysts without active symptoms in some cases.

- Two types of operations
- Ovariectomy: This is the removal just of the ovaries from the back; it is generally a less invasive procedure. In this case, the womb is left in the body.
- Full spay: This the removal of the whole reproductive tract (womb and ovaries), usually from the belly. A full spay may be necessary over problems with the womb or cancer concerns for the whole reproductive tract.
If your vet particularly favours a specific type, please consider going along with it because they will be more confident and quicker with the operation method, which can contribute to an operation success.

- Draining under GA and scan
For very frail and/or older sows with large cysts draining large cysts under sedation by using a scan can be a minimal invasive procedure when a major operation may be no longer a consideration. The result is not permanent, but will last for a number of months and can be repeated at need.
It is also a somewhat cheaper option if you can't afford the other expensive treatments/operations for large soft fluid filled cysts but it will not affect any disruptive hormonal behaviour or any do anything for any hard, potentially cancerous ovarian cysts.

Guinea Lynx :: Ovarian Tumors
Moody guinea pigs: Depression, Bullying, Aggression, Stress, Fear and Antisocial Behaviour


Other problems connected with the reproductive system

Bleeding from the anus (potential cancer in the womb or ovaries)
Sows do NOT bleed when they are in season.
If you see any bleeding from the anus (often in small drops or patches and often as a one-off event) please have our sow's reproductive system checked by a piggy savvy vet. It can be the first sign that something more serious is going wrong with the womb or a cyst and can be a sign of potential cancer in the womb or in an ovarian cyst.
You may also have a sow checked if you find a large gelatinous/rubbery mass in a sow cage; this can also be an indication of something not right in the reproductive system.

Very wet from bodily fluid under the belly (fluid-filled womb/pyometra)
It your guinea pig is suddenly very wet around the genitals, belly and legs even on absorbent bedding and if there is a somewhat strong stale smell, then please see a vet promptly and remember to ask them to not only check the urinary tract for cystitis, but also for a possible infection of the womb lining (early stages of pyometra) or for the womb being enlarged, fluid filled and/or containing potentially cancerous lumps. A full spaying operation can take care of any cancer in the reproductive tract before it can spread into the body.
Sudden increased peeing (when the urine is like water) can also be a symptom of kidney problems or more rarely diabetes. It is however important to keep the reproductive tract angle in mind when seeing a vet; it may need a scan or x-ray for any diagnosis.

Swelling/hotness around the genitalia (pyometra)- LIFE AND DEATH EMERGENCY
- Infection of the womb lining (pyometra) after giving birth ('childbed fever')
If you have a new mother or any sow not in season whose genitalia are suddenly noticeably swollen and hotter to the touch (and not just sticking out more from loss of weight - although that is also reason for a prompt vet trip!), then see a vet within 24 hours as soon as you can.
It is a symptom of pyometra, which can be easily healed in the early stages but is fatal if too far advanced. Even sows in good care can occasionally get it if their womb is going wrong.

- Burst ovarian cysts and not birth-related pyometra
Swelling of the genitalia can also be a symptom of a not birth related pyometra (womb lining infection) - which does occasionally happen even in good care. It can spread further into the reproductive tract and be fatal if not picked up promptly.
Burst cysts are thankfully not all that common, but they do happen. The sooner you can see a vet, the better the chances of recovery.

Fly strike (flesh eating maggots typically around the genitalia)
If there are small red raised dots or white dots in that area in summer or you see tiny white maggots wiggling around the genitalia, please race your piggy to vets or out-of-hours vets at any time of the day or night as a matter of life and death - this is fly strike and one of the most awful things a piggy can die from! The dots you see is flesh eating maggots.
A piggy (or other pet) can be saved if the maggots are removed in time, otherwise it will die horribly and will need to be euthanised as the kindest thing you can do. Please note that flesh-laying flies can occasionally make their way indoors and affect especially the frail and elderly that struggle to keep their genitalia clean.
More information on fly strike and what to do: Fly Strike

Lump/swelling under a nipple
Mammary tumour
Sow and (more commonly) boars can both develop mammary tumours, which can be benign or malign. A vet visit and diagnosis is a must because any mammary tumor needs to be removed in an operation; otherwise they can keep on growing and growing until a piggy can not longer have all four feet on the ground. It is generally a successful operation since it is not very invasive when done early enough.
Blood filled soft mammary tumours will go septic within a couple of weeks and will kill that way. This is an urgent operation. This type is thankfully rather rare.
Guinea Lynx :: Mammary Tumor