I'm quite happy to report that Anna has wholly recovered from whatever ailment struck her last weekend. For several days, as I reported earlier, she was unable to eat or drink, nor could she control her bowel movements. For a fastidious cat like Anna, that was a sure sign of serious problems.
Dr. Lane, an old friend and a wonderful vet who owns the Cat Clinic of Cobb, gave her subcutaneous fluids and several medications on Monday, the 13th. It didn't appear that we were seeing any significant improvements through the morning of the 14th, and I was becoming more concerned that something was seriously wrong with Anna. I made arrangements to take her back in for more fluids on Wednesday morning.
However, Tuesday night was a turning point: she began to drink on her own and to eat sparingly but steadily. By Wednesday morning, she was eating and drinking regularly, and she was wandering the house just as she always did prior to her illness. I postponed the second round of fluids, taking the vet's office up on their offer to see her almost immediately if the situation deteriorated.
Thankfully, we never had to make that second trip to the Cat Clinic. Anna has improved every day, and now she's absolutely back to her old self. I still have no idea what was wrong, since the tests revealed no toxins or infections--but Dr. Lane's treatment of the symptoms was remrkably efficacious, for which I'm eternally thankful.