Attacking the Cage!
Guinea pigs will either bite on the cage wires or bars or chew and gnaw at it's plastic edges--no matter what kind of cage or metal or plastic.
- #1 -- They want your attention, usually for food!
They may not be very hungry, but they know they don't always get food when they want it, so they pretty much insist on food all the time. Their constitution in the wild would have them grazing at grasses and foraging most of the day. They are hard-wired to be eating all the time. So, if you can, accommodate that as much as possible. Multiple, smaller meals are much better for them than one or two big meals. But at least be sure to feed them twice a day, not just once a day.
- #2 -- Lack of Hay
Provide a LOT of good quality, green, fresh-smelling hay all the time. Also, ideally provide it in two locations in the cage and not just a small hay rack. Be generous with the hay. It's the closest they come at all to a natural environment. Let them enjoy it. They need to help keep their teeth (especially their back molars) ground down and they need it for the long fibers for their digestion.
- #3 -- They like the feeling on their teeth of whatever it is they are chewing -- whether it's Coroplast or cage bars. They may have some dental issues or it may just feel good for them to bite something.
- #4 -- They are bored and attention brings activity
It may be the issue even if they run from you. But, it's usually about just wanting food. However, if your cage is too small, it could also be beyond boredom -- they are going stir crazy from being in the equivalent of a jail cell and want a real life!
Biting the Bars Prevention
Chewing the Coroplast Prevention