Hi and welcome!
Your boys have obviously hit the teenage hormones! For the next 10 months, they are being subject to hormonal spikes, which influences their behaviour. Whether two unmatched baby boars make it together to a hormonally more settled adulthood depends largely on whether their personalities mesh or not; generally more than half of the pairs that were not character matched at the beginning do, but if both of your boys are on the dominant side, they will never really get on even as adults.
Neutering in guinea pigs takes only away the ability to make make babies, but is does not change personality or dominance behaviour and in that respect it won't help your boys to get on, unlike in rabbits (where neutering bucks really makes a difference)
Your current options are:
- Give your boys as much space as you can and - after a day or so of cooling down - carefully follow our instructions for re-introductions. Brace yourself for dominance behaviour that you will have to sit through even if it is hard to bear. Separate if there are fights or if it is really very close to a fight.
Please be aware that any change of territory will trigger a new show dominance.
https://www.theguineapigforum.co.uk/threads/introducing-and-re-introducing-guinea-pigs.38562/
https://www.theguineapigforum.co.uk/threads/dominance-behaviours-in-guinea-pigs.28949/
https://www.theguineapigforum.co.uk/threads/boars-a-guide-to-successful-companionship.76162/
- lt your boys live alongside each other with interaction through the bars for mutual stimulation, so each has his own territory. There is a slim chance that they will tolerate each other to the degree that they will share run or lawn time if they have never fully fallen out, but that very much depends on how character compatible they are as adults. None of the bonding tricks that you find online can ultimately cover up the fact that two piggies don't mesh; in that respect, they work very much like human marriage/partnership.
- Here in Britain, it is much easier to find a rescue that offers boar dating, i.e. bonding with a rescue boar under expert supervision for mutual liking, so the bond has got a better chance of making it through the teenage hormones. Boars with their full hormones coursing through their bodies are the most difficult to bond for that reason, especially right now when the testicles are starting to drop until that process is finished after 6 months old.
Many boar pairs have spikes at the onset, then again around 6 months of age, which are the two times when the more obviously personality clashes happen. Around 8-10 months comes a difficult period again where it is often touch and go for many pairings. Previously mostly unaffected pairs can get into major trouble right at the end before they turn into more settled adults when most other pairs have either split or finally settled down. Adult boar pairs don't fall out much more than sow bonds; often it is due to a major change in territory/surroundings and in most cases they can be rebonded with each other again.
https://www.theguineapigforum.co.uk/pages/guinea-pig-rescue-locator/
- Neutering, so each boy can live with a sow or two. Cross gender bondings are the most stable of them all, provided that the sow accepts the boar right at the beginning. After that, fall-outs are extremely rare.
The tricky bit in going down that way is that you really need to find either a general vet with lots of practice in guinea pig neutering or an exotics vets with experience in operating on small furries to avoid adverse reactions to general anaesthesia and the sadly still common risk of post-op complications, namely abscesses. Finding a good vet it really crucial and can make all the diffierence; it is really worth going further afield for a good one. Boars can be neutered from about 4-6 months of age, depending on their physical development, weight and health; they need to pass a pre-op check by the vet.
Your boys would also face a full 6 weeks post-op wait until they are 100% safe. I have the daughter of a supposedly safe over 5 weeks post-op boar living me, just to prove that particular point and I have since heard of a few more cases of a pregnancy happening at that late stage. Neutering is not a quick and easy fix.
https://www.theguineapigforum.co.uk/pages/guinea-pig-vet-locator/
Sadly, there is no easy cure-all solution for the situation you are finding yourself in. Guinea pigs are sociable animals, but they have got very firm ideas about who they get on with in either gender, which sadly places that sell young babies for the sake of money like shops or breeders don't take into account or simply don't care about.
Boars can very happily live together if they are carefully personality matched, and they can be bonded and re-bonded throughout their whole lives. It is not they that fail, but the humans that fail
them. It takes time and experience to bond boars of any age, which is why only good rescues will do it; on average, it takes 1-3 boars to find a matching boarmate through dating, but it can take more with some esepcially rumbunctious boars. Because it is so time intensive, by far not all rescues can offer full residential bonding.
Please take your time and do your research before making any quick decisions to find the solution that is best suited to your own possibilities.
As we have members from all over the world, we find it very helpful if you please added your country and - preferably - your county as well, so we can tailor any advice and recommendations to what is as locally available to you as possible, like vet or rescue recommendations in your specific case. Click on your username on the top bar, then go to personal details and scroll down to location.