Rio has a hernia!!

Well we took Rio to the the vets today because she has had diarrhea since yesterday. She is fine in herself so wasn't to worried but thought we better just have a check up to rule anything more serious out. But when the vet examined her belly she found she has a hernia apparantly she can push her finger right through the whole in her belly
She said it should be fine and they will remove and stitch it when she is neutered after her 1st season. But what i don't really get is what will they remove and how has it caused a hole?? Has anyone else's dog had this and could it be affect her future health??

P.s the diarrhea is nothing to do with it, she thinks one of her treats may have disagreed with her

My Frankie had one and it was sorted when he was castrated, it never bothered him but as he was having a GA anyway it seemed prudent to get it sorted. Lots of dogs have them and never have any issues with them at all, basically its a gap in the muscle wall with a bit of the intestine poking through as far as I'm aware they just repair the tear by stitching and reinforcing with mesh if necessary.

Thanks trouble i've never heard of it with dogs, the vet said its a big one and that they can wrap round their internal organs which was the part that worried me. Will try not to worry to much.