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Breeding This 20% statistic


Cavy Slave
Nov 29, 2010
I've been reading a lot of the posts on these forums and one thing I keep seeing crop up is this 20% mortality rate for pregnant sows.

Now as i'm sure many people are aware 83% of statistics are made up and approximately 112% of all statistics are incorrect, however this particular statistic has been making me think.

Is 20% the mortality rate for pregnant sows under optimum conditions (whatever those might happen to be) or the actual mortality rate for pregnant sows which must be inflated by the fact that the majority of preganant sows are in the hands of breeders, the majority of which probably don't keep their pigs under optimum conditions? (I know thats one hell of a long question btw but bear with me)

I ask because as a teenager I used to take in a lot of unwanted guinea pigs (back in the days when I had the space to do it), many of which were pregnant and I can't remember losing a single one in his way.
  • Post hidden due to user being banned.
I took a quick look for the origin of that statistic. I found a number of cavy breeding sites that caution about high maternal and pup deaths, but not a reliable source of that figure. I don't have time to do it now, and may not get to it until tomorrow, but will search to see if it comes from a research study or just from observation.
It comes from a direct quote from the past president of the ACBA, Tracy Iverson: Breeding Guinea Pigs

*This is the only instance I have seen actually referencing this specific number. I'm yet to find a journal article that states a specific number.
I've actually been thinking about posting this question myself. The breeder referenced in the link is speaking of a specific guinea pig who almost certainly is over the maximum age for initially breeding a sow. I have no doubts that breeding older (over 7 months) pigs for the first time would result in mortality rates that high. But, unless I'm presented with real research to the contrary, I'm not buying that 20% of young sows (or older, previously bred sows) die during birthing. That said, I 100% encourage rescue and discourage breeding based on overpopulation alone.
Read the quote closely. It states "...since breeding a sow means a 20% chance she will die...". This is not a reference to a specific pig, it is a deliberate reference to sows in general, used to relate why she isn't going to breed such a "show-worthy" pig. Coming from the president of the official cavy breeding society in the US, I would say it is likely an accurate figure.
Surfing Pigs - point taken. If I can see the research I'll believe it. But I worked for 10 years at a veterinary clinic - and never saw numbers nearing that. One of our technicians bred her pigs during that entire time and never lost a sow. Not saying it doesn't happen, but from what I saw then and even what I see on these boards now, the 20% statistic is hard to swallow.
I, too, would like to see the research before I begin espousing that number, but since I have yet to find it, I will continue phrasing my issue as "risking the life of the sow." That is an undeniable fact, that sows can and do die from breeding/pregnancy in general.

Think about the typical person who comes to these boards for a second... are you going to assume they are "average" caregivers? Of the probably more than tens of thousands of guinea pig owners out there, only a fraction of a percentage of them participate on internet forums. These owners must really care to be doing research, and thus overall are likely providing a higher-than-average level of care. So of course you don't see this number on the boards. Hell, many people here are volunteers/vet techs/fosters/rescuers, of course we have a higher standard of care for our animals.

I would bet that your average pregnant pig in the average American home probably has a mortality rate nearing 20%, and that is what this is about.

Congratulations to your work friend. My grandmother smoked a pack of cigarettes a day and lived to a healthy 95, I guess that means smoking doesn't cause lung cancer.

Perspective, people...
You are absolutely right, SP. Breeding is most certainly risky for the sow, regardless of the statistics. I'm really not trying to be a brat, and I apologize if I've come off as contrary. I truly am as anti-breeding as anyone here. In a way, I'm hoping that the 20% can be documented. Obviously I don't want piggers dying, but I think numbers that high can be an extremely effective deterrent - and I'm all for using any deterrents we can find.
HCB: You didn't come off bratty. I think you and I are both a bit disappointed that we can't find the source of that number. I tend to believe the President of the society would have a fairly strong understanding of that and of the implications of making that statement if she didn't have something to back it up, but I could be giving her too much credit. Either way, I think we see eye to eye on most of this.

I was just trying to make the point that, at least for me, I find myself forgetting that the way I care for my guinea pigs is probably much better than most. When a parent goes to Petco and is told to house two pigs in a tiny cage, and to just feed the pigs some hay and an orange slice a day and some water with vitamin c in it, the parents unknowingly provide a really poor level of care. These are also the people who get the pigs from Petco that are already pregnant, which is ridiculously common. Then, these pigs die from the poor nutrition and poor care because these parents, who did just what Petco said, were providing a terrible, unsustainable life. I think this is a very common and unfortunate situation.
Of course if I was to put on my anti-breeding hat (I do have one somewhere... ah, there it is under my 'hit irrisponsible bankers with large mallets' hat) the statistic could easily be turned around and it could be said that those of us who do provide a high level of care are in fact dragging the average down, thus the mortality rate of pregnant sows owned by breeders and muppets (you know the kind of people i'm talking about) may be significantly higher.
I think, like many other "statistics" cited on this forum and others, it's something that was mentioned somewhere once or twice or may have once been thought to be correct (the "proper" balance of calcium to phosphorus in pig diets comes to mind) and most folks tend to take those types of things as gospel and perpetuate them rather than doing what you've done, which is question where it originated and whether or not it's accurate and/or still valid.

That said, I personally know of three sows who died during labor or as a complication from labor - two of which were accidental pregnancies, one of which was a breed-back, the other was with a breeder whose facilities I have seen and while I disagree with what she's doing, I can't say that her conditions are insufficient or her care lacking in any way. THAT is enough for me to suggest that a potential risk of pregnancy is death, and therefore not advisable.
Statistics have a lot to do with the population size reporting. You may never get a reliable statistic, so the OP has a point about the number.

That said, guinea pigs are unique rodents in that they give birth to fully developed offspring - full teeth, hair, claws, etc. - which means that regardless of the statistic of other rodents that reproduce providing altricial offspring (undeveloped and completely dependent on the mother, hairless, toothless, clawless, etc.), the mortality rate of the sow is going to be higher. Once the pubic symphysis is irrevocably fused (the cartilage joining both halves of the pelvic girdle), the likelihood of death goes up even more.

I'm not sure the statistic is the point. I personally believe that biology - the reproductive cycle and developmental biology and anatomy in particular - would give a curious person enough of a basis to take an anti-breeding stance. There is anecdote and there are trends. The question any individual should ask is if you really *need* another guinea pig and is it really that important to obtain them from conception. My feeling is no, albeit I'm sure others would disagree.
It annoys me that there's a constant "need" to quantify things - if you were looking at quantifying and clarifying this 20% figure then you'd be looking at huge sample sizes, control groups and data collection under experimental conditions - none of which are exactly representative of breeding practices that go on across the world. I think there comes a point when people need to accept that breeding (any animal, including humans) comes with a risk attached and base their decision on that.
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