HELP! - Boar with Sows; Boar Bullying :(

[CurvyCavies]

We adopted 5 guinea pigs, and one ended up being pregnant with one little boy. We named him Little Man and kept him seperate until he could be neutered. He is neutered and healed and we introduced him to the herd. They took a couple days to rerank themselves, which is always a hard transition. But it has been 2 weeks and Little Man seems to be really picking on one of the sows, Piegan. Ever time he sees her he chases after her and if she is walking around and sees him, she runs into the corner to hide. Last night he pulled out some fur and left a mark on her backside.

We have been holding Piegan more because we feel bad for her and we held them together this morning cuz I know sometimes they see how we interact with each other and we were hoping it would help her not be afraid. But then he lunged at her face and attacked her.

We really dont want our human emotions to go into the decision to separate them again but we're really not sure what to do. Do you think this will work itself out? Should we separate the boar again? Should we separate the sow? She has always been in a bonded pair and is very shy to begin with, but we have seen her come out of her shell until he came into the herd.

HELP!

 

[Piggies&buns]

Welcome to the forum and I'm sorry to hear they are having problems.

Has it been six weeks since he was neutered? That is the required time for them to wait to become infertile before a boar can be introduced to sows

If an injury causing attack has taken place, then it sounds as if they do need to be separated. It takes two weeks post introduction for them to fully form their relationship but if they decide they dont like each other and cannot form a relationship, then things will not work themselves out.
It would be best if Piegan and Little Man are kept apart but so that neither of them are kept alone, herd could be split so that each of them still have company - three piggies in one cage and two in another.

Bonds In Trouble

 

[CurvyCavies]

It has not been six weeks. We introduced 3 weeks out after research. Haven’t heard 6+ weeks anywhere =\ would waiting another couple weeks help with his aggression hormones as well as fertility?
We separated him and he is able to see the girls through a c&c barrier. This is how he grew up mostly, aside from after surgery. He gets along well with his mom but we are leaving town for a week and most likely will keep him by himself until we get back to avoid conflict with the pet sitter.

 

[Piggies&buns]

It has not been six weeks. We introduced 3 weeks out after research. Haven’t heard 6+ weeks anywhere =\ would waiting another couple weeks help with his aggression hormones as well as fertility?
We separated him and he is able to see the girls through a c&c barrier. This is how he grew up mostly, aside from after surgery. He gets along well with his mom but we are leaving town for a week and most likely will keep him by himself until we get back to avoid conflict with the pet sitter.

It’s nothing to do with aggression (neutering doesn’t change their behaviour) it’s all about fertility. Six weeks post surgery is standard - they can remain fertile for six weeks after neutering so there is a chance he may have caused pregnancy(ies). @Wiebke

The guide below has further details

Neutered / De-sexed Boars And Neutering Operations: Myths, Facts and Post-op Care

I would strongly consider splitting the girls and having two separate groups going forward for everybody‘s long term happiness.

 

[Wiebke]

The little baby in my avatar picture on the left (Tegan Syndod 'Little Beautiful Surprise' in Welsh, 2011-19) was the unplanned legacy of a supposedly safe over 5 weeks post-op boar (not one of mine, I hasten to add), just for a verifiable first-hand experience that it can really happen as late as that. A vet removes the testicles but not the tubes leading to the penis. Semen in those tubes can stay life for quite a few weeks or even months.
Practical experience in good UK welfare rescues has shown that our recommended cut-off point of 6 weeks is the 'sweet spot' between safety and the risk of an accidental prgnancy becoming so low as to winning a lottery. In all that time we haven't heard of an over 6 weeks pregnancy despite thousands of boars having been neutered in the last decade.
I hope that this explains the wait? A 2 weeks post-op a boar is only about 50% and by 4 weeks about 90-95% safe - this meant that while 4 weeks was still the general post-op wait recommendation before the switch to 6 weeks by the RSPCA and other good standard rescues, we would be contacted on here over a surprise birth often enough to know that this period was too short.

Please also be aware that neutering basically just takes away the ability to make babies; it doesn't change libido, social behaviour or outlook in personality. Neutered 'husboars' behave just the same around sows as full boars and will mate when in season. Bonding success is not guaranteed if acceptance fails on any level of the group hierarchy when the ranking cannot be amiably sorted, which is the hurdle your bonding attempt has unfortunately fallen short of.
Bonding and Interaction: Illustrated social behaviours and bonding dynamics (See chapter mixed gender bondings)

I do agree with the recommendation to split your group. A failed bonding is always very gutting but once piggies have made up their mind that they don't suit, they are not going to change their minds pretty much for the rest of their lives.