Hi, first time post,
I'm in the US and I adopted a 2-3 mth old guinea pig who was misgendered (I know I'm really sorry, this is a learning lesson, all guinea pigs will be taken to the vet from now on for gendering) both myself and the breeder checked them and didn't see anything.
We think he may have gotten my almost 4 year old pregnant. It's been 12 days and she's been steadily gaining weight. My vet says she's too old to have babies and needs to have it,"taken care of" through being spayed. Is this right? Also, my vet doesn't do this, so she wants me to go to a specialist that may or may not exist within 3 hours of us.
What should I do? I'm really scared for my girl and am not sure what course of action to take.
Hi and welcome
I am very sorry for the nightmare you are finding yourself in through no fault of your own. Sadly many owners learn the lesson of double-checking their piggies upon arrival the hard way.

You may find our sexing guide helpful as we have included how to check on less obvious areas where the gender is MUCH clearer yourself. Unfortunately, vets that don't see lots of baby piggies may struggle with the sexing as much as you do.
You are of course always welcome to ask us for our opinion, but you have to be prepared to be asked to please do these hands-on safety checks as sexing from pictures has got its limits, and we refuse to play guessing games on here.
Sexing Guide
How long has your baby been with your sow and how long since the separation? A pregnancy lasts 10 weeks on average. Weight gain is not steady; for about two-thirds of a pregnancy (a bit sooner with a larger litter and later with a small litter), you don't see any real signs and weight gain while the real weight gain happens in the last about 3 weeks and depends very much on the size of a litter.
It is very much a between a rock and a hard place decision you have to make; unfortunately there is no easy option and you have to weight up the various pros and cons.
On one hand, in older sows, the risk of a miscarriage with dead-born babies or babies that are not able to survive is generally much higher. The risk of embryos failing early on and only one large pup developing that cannot be pushed out and requires an emergency cesarian is also higher.
On the other hand, a spaying operation is a major operation that comes with its own risks.
I would say from my experience, the risk of fatality for your sow is about even in either case but without quick access to a piggy savvy vet in case of birthing complications, a spaying op is well worth discussing with a more experienced vet.
Unless your sow has got a single larger baby, your mother has a good chance to survive on a good nutrionally balanced diet without overfeeding on veg and pellets (which are the main contributors to large babies). Please see our pregnancy advice link; you will find precise diet advice right at the start of it. Whether any or all babies make it is very much more in question with older sows.
We have seen several old mothers make it through giving birth OK on here over the years, but in many cases the babies have not made it.
If it does help you, I am currently looking after one of my own sows, a five year old that has been spayed on Thursday because she was found to have one of the rarer ovarian cysts that would have turned cancerous if left. She had a dodgy night after her return here and needed syringe feeding support as well painkillers and gut stimulants but she is now back to eating fully by herself and her operation wound is healing well.
She is the fourth sow I have had to spay for medical reasons and the second 5 year old (who did come through her operation well and without any problems).
Thankfully I have got access to a very good operating vet about an hour from me.
Sows: Behaviour and female health problems (including ovarian cysts)
Tips For Post-operative Care
I would recommend to seek a second opinion from the vet you have been referred to before making any decisions.
The problem is that you will have to need to make the decision blindly. There is no pregnancy test for guinea pigs.
In our experience, the earliest that babies can be found reliably by ultrasound with a very piggy savvy vet is about 5 weeks; ideally from 7 weeks when inner organs can no longer be mistaken for embryos (which we have seen a number of cases of over the years). Since I don't know how far along your sow is, I don't know whether a scan to check for babies is an option or not.
Here is our pregnancy and birth advice collection, which also contains a link to a thread with a collection of pregnancy ultrasounds and x-rays:
Pregnancy & Baby Care Guide's
Again, I wish there was an easier solution to your problem!