I wouldn't use Gorilla glue on his incision. Has he been licking? That could be what is causing it to separate. You are now 5 days postop so the vet is not going to put more stitches into his incision. Do you have either a onsie or a ecollar that you could put on him so that he cannot lick? If I were you I would give your vet a call in the morning to be sure he does not need to be seen.
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