Until today, it is still unknown why both grapes and raisins are deemed fatal to dogs. I've made a research on what kinds of foods that won't do any good for dogs and when grapes fell into that category, I thought it was because of the seeds. Further research explained in turn that it doesn't matter if the grapes ingested by dogs were with or without any seeds. I know that practically anything processed is bad for them because their kidneys cannot filter salt the way humans do. Perhaps it's the same with grapes because of the possible sugar content? I'm not sure about this so until a new study has come up with regards to renal failure in dogs, all we pet owners need to do is to steer them clear away from grapes and raisins.
