Help! My guinea pig is pregnant, what can I expect?

This topic is huge, and unfortunately, not a lot of information is available on what exactly happens during a pregnancy, what the risks are, and what to do after the fact.

First of all it's important to realize that a sow is capable of going into her first heat cycle at about 24 days of age. She will then cycle every 16-18 days from then on. Baby boars on the other hand, are viable at about 20 days of age, as soon as the penis can penetrate out of the sheath. A boar typically will breed until he's about 4 or 5, the oldest boar I can validate was a silkie boar that sired a litter at the age of 6. A sow typically begins to slow down her reproduction around 3 or 3.5 years, and may not be receptive after 4 years of age. The oldest sow I personally know who delivered a live litter successfully was about 4.5 years of age - she had a litter of two babies and nursed them to weaning age, bounced back and lived another year. I have also seen a few baby sows that were impregnanted by their brothers before 4 weeks of age, so while it's not common, it is possible.

There is a lot of myth surrounding this 'pelvic fusion' theory. There are people out there who insist that a sows pelvis will fuse rigidly shut at about a year of age. It is more my opinion that the bones fuse shortly after birth, same as ours do, but the ligaments and muscles tend to lose their elasticity over time. This is much like an older woman giving birth for the first time - she's likely to have more problems than a 25 year old woman giving birth. An older cavy (over a year of age) who is having her first litter is simply at higher risk than a younger sow.

Now, should you choose to breed your sow, or even if you have obtained a rescued sow, a owner relinquished sow, or even purchased a sow from a pet store that ended up pregnant, it's important to have a knowledgable cavy vet on hand if you need it.

Sows gestate their young for 70 days. This is a very long gestation, but the babies are born fully haired, eyes open, and ready to go. Most of the time you have no idea when she was bred, but I'll list some basic time frames. You won't be able to see any outward signs of the pregnancy (other than lack of a heat cycle) for the first month. At about 35 days, the sow will start to plump out, and take on a thickened 'waistline' or pear shape. At this time, the babies can be palpated through the mom's tummy. At about 50 days, you can feel them kicking inside the mom. At this time, you should STOP handling the mom about the abdomen area, as a mere incorrect bump can cause a placenta to detach, and can lead to a toxicity in the mom, eventually leading to her death. I use a dust pan, or a small box to move mom about if necessary.

Her pelvic girdle will start to separate at her due date, which can be any time from 67 days to 72 days. You may place her on a flat surface, holding her head but not touching her abdomen, and slip your fingers under her. Slide them just above her vulva (towards her tummy) and you can feel two points. These are her hipbones, and they will 'dilate' when she is ready to deliver. The points are close together (feel a virgin or non-pregnant sow) nearly touching, and when she dilates, she'll be fully dilated when they are about 1/2" apart. This typically happens about 2 days before she delivers, but sometimes the sow will trick you - the hipbones will come back together again! Fear not, she will go into labour in the next few days.

She will typically have her young in the wee hours of the morning, around 5-6am. You will wake up and usually find warm, blinking confused looking youngsters, with no trace of afterbirth, bloody shavings, or any evidence. This is instinct for the mom, to fully clean up the 'den,' to avoid attracting predators to the blood.

If you are lucky enough to be present, you will see the sow actually contract, small ripples of muscles pushing up her body. She will then reach underneath her (as if she's digging for coecal pellets) and will help pull the baby out of her canal with her teeth, breaking the amniotic sac in the process. Now, the full delivery will usually take less than 20 minutes, so beware, it happens quickly! She will eat the sac off of the baby, and try to lick it clean, often times as the second baby is starting to crown. Sometimes in the furor, she can inadvertantly be attending to one baby and will not be able to attend to another baby in time to unsac it and you will occasionally have a baby drown in the sac. First litters are generally about 2-4 babies, backbred litters are generally larger. As you can see, there is a lot of work that the mom has to do very quickly! The mom must eat the afterbirth - it containst oxytocin, a drug which stimulates contractions of the uterus as well as milk production.

She will be busy for the next few weeks. Keep lots of good food in front of her, and plenty of water and vitamins. A trace mineral block is helpful, but some pigs ignore them. Vit C (about 30-50 mgs per day) is necessary as she passes this on to her babies. She should also have calcium available, to help with replenishing her own bodily resources, but to also help her produce calcium rich milk for the babies. Good sources of calcium are parsley, kale, collard greens, dandelion leaves and mustard greens. Some people use a slice of wheat bread soaked in whole milk or goat's milk (called bread or milk sop) and offer this to the mom and babies. Some folks will tell you that cavies cannot utilize milk products. It's up to you to decide what you want to try.

The babies can be weaned as soon as they are eating and drinking well. I like to leave babies in until they are 10 ounces in weight, but boars should be pulled as soon as their penis is able to be extended from their sheath - they are viable at this time and can impregnate their sisters. I will put them in with adult boars, often their fathers take to this job nicely. I will however, leave baby sows with their mothers, unless they are being coated out for show.

A week from when the sow is due to a week after she delivers, you want to make sure that she is eating, drinking, and active. She might slow down prior to delivery, but she should continue eating and drinking. Failure to do so might indicate a more serious problem, either her system is not able to handle the waste products of the babies and her own, and is starting to go toxic. If after the delivery she sits around not eating, looking 'fluffed,' this could be a sign of a retained placenta which can slowly poison the mom. She will need to go to the vet in either case, if you hope to save her. Another thing you will want to verify is that she gets her milk within the first 24 hours, failure of this will result in dead babies from lack of nutrition, as well as a systemic infection if the mom's mammary glands have mastitis, a blocked duct.

Other links for more info:
Cavyland - tips on breeding
Seagull's info on breeding
CavyCare site info
Peter Gurney's pregnancy info

If you have any questions, please feel free to email me at