While I was at work today, Joe brought the Coop back to the vet to get re-stitched. A week and a half out, she was still gapping too much for his taste, and he could reportedly see a little patch of muscle through the wound. So she got closed up again. Luckily, she only needed some local this time, so she was as perky as ever after the procedure, not all stoned like before. The T-shirt will probably stay on for another week at least, and she'll be taking another course of antibiotics just to be safe.
The antibiotic, by the way, is called "Clavamox," which the vet told us is the canine equivalent of Augmentin.