Dog(s) might have eaten ate something they shouldn't have, help!?

so i have two labradors. today they were outside and i went over to them and found that there appeared to be part of this old corncob chewed up. it was dry and brittle, so if chewed it's quite possible it was in small pieces, and wouldn't result in a problem. it's also possible that they didn't even eat any of it, or that only one of them did. we called the vet and asked what to do, and they said to induce vomiting for both of them, so we did, and they vomited. is there anything else we should do/be worried about? are there any similar stories? the vet said if there was a problem it would be an "obstruction" or something like that, and they said just to look out for lethargy. which isn't easy because they're lazy anyway.