A few people have emailed with questions because their kids are interested in getting guinea pigs or other small pets of their own. I can’t claim to be an extensive resource for all things cavy, but I can share our experience with how much our kids really help take care of them.
We’ve had a dog and a couple of cats since before Eleanor born, but she had been asking for a new pet for about a year. Both Brandon and I grew up with pets (he had a rat and his family had dogs, cats, and bunnies — my family had a dog and a cat too, and over the years I’d had a rabbit, a hedgehog, fish, mice, and a hamster), and we agreed that E seemed ready for one of her own. She checked out a different book about animals each week from the library throughout kindergarten, in part because she loves all kinds of animals and in part because she was doing her research. For her, it came down to hamsters and guinea pigs. Hamsters have fun cages with crazy tubes and lookout towers, but they’re more fun to watch than to hold. Guinea pigs are larger and more docile so they’re easier for kids to play with, but they take up a lot of room. E made her decision and went with her grandparents for her sixth birthday to choose a pet, cage, and everything to go along with it. Guinea pigs are happier in pairs (thanks, library book), and after a week or so, we found another female to join our house… except she was a he, and then they had babies.*
So now we have two giant pet cages — one in Eleanor’s room with the girls (Speedy and Butterscotch), and one in August’s room with the boys (Gingerbread, Noisy, and Cute-Cute until he left yesterday for a new home). August likes them well enough, but either because of age (four) or temperament, he’s not as into them as E is. She loves the guinea pigs.

Cleaning the Cage(s)
I organized all of the small pet supplies along the floor of our linen closet — food pellets, hay, chew sticks and toys, and clean bedding. (The best bedding is paper-based — pine and wood shavings are messy, smelly, and best avoided.) Guinea pigs are little poop machines, but they do tend to go more near where their food is. We clean that section as needed with a small dust pan reserved for the job, and then we completely change out the bedding once a week.
Eleanor can do it. Kind of. It takes her a long time and she makes a bit of a mess, so I usually do it with her while she ‘helps’ by holding the garbage bag. I want her to be there, not because I need the assistance, but because her pets are supposed to be her responsibility and she should know that they aren’t magically being cared for with no effort on her part. As she gets older, she may be able to change the bedding by herself, but I assumed going into it that Brandon and I would be helping for a while so it’s not a shock that I’m doing it. I am unfortunately allergic to them, so I sneeze and sniffle through the process (about 15 minutes per cage).
Food and Water
Eleanor can and does make sure there is food and water for the guinea pigs at all times. They need fresh fruit and veggies, and E likes figuring out what they’ll eat each day. We often give them any leftovers (carrots, apples, etc.) that the kids didn’t finish from their meals, but sometimes E has me make a teeny tiny fruit salad to serve. Adorable. The only part she has trouble with is the hay because it can get messy, so Brandon and I usually do that part.
Socializing
The girl loves her pets. Eleanor couldn’t pick the guinea pigs up at first because they’re quick and nervous by nature, but she’s good at it now and no longer needs help catching them. She has done a good job of taming them, and even thinks they do tricks and communicate with her in a secret animal language! Calvin likes to watch them run around their cages, and August will pet them when they’re already out and being played with, but he doesn’t take the initiative like E does. She wakes up and pets them. She has gotten out of bed at night and slept on the floor to be next to them. We wondered (as a lot of parents do) if interest would wane but Eleanor is just as into them now as she was in the beginning, and I think the responsibility of caring for them has been good for her.

Cute-Cute Goes to School
Yep, we’re less one guinea pig around here; Cute-Cute is now a school pet! He won’t be in August’s classroom, but just down the hall with another teacher. Eleanor was in school when Brandon and August took the little guy over, so I had them take a bunch of pictures to show her. They used the pet carrier toy from Eleanor’s vet set, and she thought that was pretty funny. She was also excited to see that there is a cage all set up in the classroom just like the one he was living in here, and that he’s going to have lots of new friends visiting him each day.

* According to Eleanor: if our guinea pigs have any more babies (please no — but apparently they mate immediately after birth, which we didn’t know and I’m watching Speedy get fat…), the boys will be named George and Jr. and the girls will be Lily and Twilight.