Happily, a trip to the vet this morning quickly set the ailing kitteh back on the path to health. One geriatric blood and urine screening (eliminating the feared kidney and thyroid issues), one pair of anal glands expressed, one long-lasting antibiotic injection, one subcutaneous electrolyte drip, one kitteh morphine injection, and five hundred dollars later, Sputnik is returning to her sleek and sassy self.
She is now eating, drinking, urinating, and has a renewed interest in life. In fact, she even snuck back into the urban assault vehicle after I was so careful to carry her out of the car upon returning home, so that she wouldn't have to cross the ice field that they call our street. She is not a huge fan of car rides, so this desire to climb back into the car is highly unusual, and I strongly suspect that she simply didn't want to waste a good stone, when she could be grooving to tunes and watching the telephone poles whizz by.
Sputnik is definitely not the same feline she was yesterday, and that is worth every penny.