Any piggy can get ringworm if they have been in contact with the spores.
Pet shop piggies are more at risk of bringing home illnesses whereas rescue piggies from a reputable centre will have been vet checked and declared healthy before they are available for adoption.
There is more to consider than just ringworm though.
When adding a single sow to an already bonded pair, you have to be prepared that the bonding may not work out.
There is also the outsider situation which can occur when working in trios of sows.
Adding a baby piggy (ie one younger than the two you currently have) has a better chance of success because the baby cannot challenge your dominant sow for the hierarchy.
Adding an adult (ie one the same age as or older than your two) means that she may well challenge your dominant sow for the hierarchy. If you end up with two dominant sows, the bonding will not work out successfully.
Adding a neutered boar will stand an even better chance of being successful as sows of the age yours are would be much more likely to accept a boar than they would another sow. He will be a natural outsider to your dominant sow but he still has to be accepted by both your sows for the bonding to work.
If you were to bring home a piggy (either an adult
Or a baby) from anywhere other than a reputable rescue centre for you to try an on spec bonding, then you would need to:
1. Need to quarantine any pig over four months of age in a separate room for two weeks before bonding. A baby piggy under four months of age cannot be quarantined so you would need to bond straight away and take the risk of it bringing in an illness.
2. Have a plan b in case the bonding fails. That is having a separate cage for the new piggy to live in side by side with your pair (as well as the possibly of having to bring in a fourth piggy to bond with the one who is single).
The best thing is for you to contact a reputable rescue centre who offers dating. You then take your two sows to the centre so they can be tried with either a neutered boar or other sows - whichever you choose to want to try.
That way you can be sure of compatibility and a successful bond (without the risk if the bonding failing) before you bring another piggy home.
Also ensure your cage is big enough - that is a 5x2 c&c or a cage is 180x60cm for three piggies
I’ve added some guides below to help further
1 Singles and Pairs
Singles: Challenges and solutions for different singles situations (link)
Pairs: A closer look all possible pairings (link)
2 Trios and More by Gender
Boars
- Trios and quartets - Why better avoided
- Large Groups...
1 Intro: Reality check on where your pets come from
2 Are guinea pigs really the right pet for me?
3 Rescue adoption
- What extra services do good rescues provide that other places don’t?
- What about not recommended rescues? How can I spot a bad place?
- Shelters and rescues – is there a difference?
- How does the adoption process run?
4 Pet shops
- How will you choose your pets?
- Why...