Fur loss in guinea pig?

[Nancyclancy]

We have 2 guinea pigs and have in the last week taken in two more.
When I collected the 2 recent ones, they were bedded on hay only, no shavings etc. The hay was also damp.
I bought them home, cleaned them out. Their cage is lined with newspaper, wood shavings, straw in the bed area. They have been eating well and had veg daily and plenty of hay along with their hard food.

Anyway, one guinea pig (the more nervous of the 2) is absolutely fine, but the 2nd (slightly braver) has patches of fur missing around her neck.
When we handle them, we've not noticed her itching or showing any signs of distress. I wondered if it was mites as one bit has a bit of blood. But if one had mites surely the other one would too??

When I first collected then I did notice once I'd got them home that her fur around her neck was a bit patchy so have kept an eye.
I'm just wondering if she's stressed, being bullied by the other guinea pig or whether it's her new diet? Any ideas?

[grunty]

I would bring it to the vet in the morning. The only time I have seen hair loss was mites and you need to treat asap. I would bring both of them.

[70isaLimitNotaTarget]

I routinely treat for mites even with no symptoms.

Mites tends to give a snapped off look to the hair strands and is usually on the rump BUT obviously not all cases are alike.

Your guinea could be self barbering or her cagemate might be barbering her.

Most guineas do carry a low grade mite load but if they are stressed, the problem can take hold and their skin flare up. Mites can kill.

Your vet would most likely treat the pig pair (we use drops on the neck Xeno 450, but not all pig users favour this as there have been cases of sensitivity and fitting. We just have to keep ours apart for a while till it dries so they don't groom each other. The boar is the one who preens his cagemates)

You'd need to disinfect /dispose of all their bedding and start afresh ( steamers are brilliant to clean piggie houses. No residue to worry about)

[70isaLimitNotaTarget]

And as things are never straightforward you need to rule out fungal/ ringworm/scurvey/lice