More space for underweight guinea pig

A vet flagging both underweight and insufficient space at the same time is really useful information — those two things are often connected. Guinea pigs that don't have room to move, graze freely, and express normal behaviour can become lethargic, lose condition, and struggle to maintain weight. Before I point you toward anything specific, can I ask: is your White Crested on their own or do they have a companion? And are you looking to replace the current enclosure entirely, or add to it?

Good that she has a companion — that matters a lot for condition and stress levels. And yes, most pet shop cages are genuinely too small for two guinea pigs; the minimum recommended floor space for a pair is around 120cm x 60cm, and many sold cages fall well short of that. What does your current setup look like — are you indoors, and do you have a rough sense of how much floor space you can give them?

In that case I'd go straight to the Midwest Homes for Pets Guinea Habitat Plus. It's 151cm x 79cm of floor space, which is genuinely one of the best footprints available for an indoor pair without going full DIY C&C grid. The mesh panels fold flat for cleaning, there's a canvas bottom that's easy to spot-clean, and it's low-sided enough that guinea pigs can actually see out and feel part of the household — which matters for an animal that can become withdrawn when stressed or underweight. It's also widely available on Amazon UK, usually arriving within a day or two. For a vet-flagged underweight pig specifically, more usable floor space to graze hay continuously is one of the most practical things you can give her alongside any dietary changes the vet recommended.

It's manageable if you stay on top of spot-cleaning every day or two. Most people put a layer of fleece liner over the canvas bottom — fleece wicks moisture away from the surface, it's washable, and it doesn't harbour bacteria the way paper bedding can when it gets damp and sits. A weekly full clean of the canvas with a diluted pet-safe disinfectant is enough. Given your girl is already underweight, keeping the environment clean and low-stress will support her recovery alongside whatever the vet has prescribed.

Great choice. Once she's settled in the larger space, keep a close eye on her weight weekly — a kitchen scale and a small notebook is genuinely one of the most useful tools you can have with guinea pigs. If she's not gaining after three or four weeks despite the extra room and any dietary adjustments, it's worth going back to the vet to rule out dental issues, which are a common hidden cause of weight loss in guinea pigs her age.