Bald spot with sore

[destinyheaven]

Hi all,
I have 2 guinea pigs. I rescued one about a month ago and after he was better I adopted another one so he could have a friend. They are friends most of the time but they are both male and fight a little. The younger one gets annoyed and chatters his teeth at the older one if he bothers him too much. They have a little fight here and there.
I noticed a little bald spot on the end of my older one’s tail bone. It has a little sore that looks like it’s mostly healed. The cage is clean, they have a good diet. It’s only on my one older guinea pig. Any idea what this might be? Hopefully it’s just a fight mark that’ll heal up on its own. I inspected both of my guinea pigs throughly and this is the only mark. No signs of mites, lice. He’s not a very itchy pig. The closest vet to me is 3 hours. I’m in a very rural area.

 

[destinyheaven]

 

[Piggies&buns]

That’s his grease gland.
They can get infected so it should be checked by a vet if there is any soreness

Bathing (including cleaning grease glands)
Boar Care: Bits, Bums & Baths

Compatible and happily bonded guinea pigs do not fight. There will be dominance behaviours but there should never be any fights.

How long have they been together?
Did you bond them properly on neutral territory?
Is their cage 180x60cm (70x24 inches)? (Anything less doesn’t provide enough space for two boys).
Is there two of everything in the cage?
Do all hides have two exits?

You have to be very clear about what you are seeing in their behaviour.

If it is just dominance (ie what you are describing as fights are not actually fights and they are not causing any injury whatsoever to each other) , and their environment meets size, hides etc - then you leave them to it. Fully bonding takes two weeks so during those first two weeks there is additional dominance while they establish their hierarchy. You will also see dominance throughout life as they keep their bond going and if either of them are teenagers (between 4 and 14 months of age) then the hormones will cause additional dominance.

If your piggies are actually fighting or are having any bond issues more than just dominance (some bullying does not cause physical fights but it would cause a very unhappy piggy), then they cannot and must not remain in the same cage as each other any longer.
Fights are a failed bond and piggies who don’t like each other and if you keep them together things will get much worse.
In that event They must be separated into their own 120x60cm cages which need to be side by side for interaction between the bars but no more physical contact with each other.

Pictures can be deceptive but the little run in the picture does not big enough for two boys. Lack of space will cause big issues between the boys potentially enough to end a bond.
We would also recommend that there are hides and hay provided when they are outside.
Do note that any access to fresh grass has to be built up slowly over several weeks as fresh grass on an unprepared gut make them unwell.

Bonds In Trouble
Boars: Teenage, Bullying, Fighting, Fall-outs And What Next?
A Comprehensive Guide to Guinea Pig Boars