I give them lots of fresh grass. They are actually eating the cardboard though. Is there any way to keep them from eating the coroplast?
I don't know if it's ok to give them just fresh grass and no hay, but is that what you meant to say you are doing in that quote? If it is, then maybe try giving them unlimited hay, and supplement with limited fresh grass.
Do you try to follow Ly's nutrition chart as far as daily veggies and occasional fruits? Also, how are you feeding them their pellets? Like, what brand pellets, how much, how often do you feed them?
Just curious, because although I don't know about cavies and pica, or if they can even get that, but I know that sometimes when dogs eat inappropriate objects (which are oftentimes paper/tree-based items like cardboard), they might have a dietary insufficency of fiber. Or at least thats what a vet once told me. Some dogs just do it inexplicably.
Maybe Ly&Pigs knows whether or not piggies can do that, or if they can get it as bad as pica.
But I like what deenanicole08 said, about their teeth in the back still needing to be ground down by something, since hay really only takes care of the front ones.
Many people on here give their cavies twigs from non-pitted fruit trees. Make sure it's non-pitted (like for example, choose apple wood sticks instead of peach wood sticks, peaches have pits, apples do not), and free from chemicals and fertilizers, and pesticides. Thats about one of the few safe things to give them to chew on, Ly told me to avoid giving them the chews found in pet stores, because those are artifically colored, and sometimes artifically fruit flavored too, and some are just materials that aren't healthy for cavies to munch on. If you can find some of the Tropical Fiddle Sticks, I bet your pigsters would love those. One of mine, Opal, sits there and gnaws away on the rim/edge from the inside. And she likes going all the way in and reaching up a bit and nibbling the ceiling. She also liked chewing on those snak-shak tunnels and huts, but I realized she was actually eating those because they are technically edible, and the ingredients are a no-no, so...had to take those away.
You could try some of that bitter apple spray or gel, but I have personally found that that stuff doesn't even work for my dog, which is the species it is aimed at, but you could give it a try, just keep the receipt. It did work for my very first hamster when he wouldn't quit chomping away at the top of his water bottle. He didn't go up there that often after I put that stuff on there. I've gotten it in my mouth before, and it's absolutely horrible:yuck: ....and wear gloves if you decide to try it, b/c it absorbs into your skin and doesn't come off with washing, it takes a few days until it dissapears.
Or try spraying some 50:50 water and white vinegar solution on the coroplast. There's some website that has photos of some lady actually climbing inside the c&c cage, and in the one where she's sponging it down with that solution, she put a caption that said if her piggies come too close and sniff the solution, they scatter like a bolt of lightning. So, apparently her pigs are very averse to the smell of vinegar, maybe yours are too..
Oh and I'm sorry everybody that my posts are always so long...it just happens, sorta like the process of cavy pooplets..they don't have the same highly functional sphincter muscle that people have, or that dogs and cats have. Its just like: "La dee da dee da.....
oh my! What do we have here?"
Good luck!
Hope that helps!!