The good news is, it needn't be that cerebral haemorrhage I'd feared. I'd reached that conclusion on the basis of one of my previous cats, Dickie, displaying the same symptoms 13 years ago, and I had to have her put to sleep; but veterinary science appears to have come on since then and Leila's condition has now been diagnosed as vestibular ataxia. The bad news is that in this early stage, it's impossible to tell whether we're dealing with central or peripheral vestibular ataxia. If it should be the first, then the prognosis is bleak; if the latter, she ought to improve with treatment over the next 3-4 days. She's been given a steroid injection, and another one to combat the nausea she's experiencing (as evidenced by her throwing up just before we left to see the vet), and I have been given strict instructions to keep her warm, safe and to make sure she gets enough food and water down her, for which purpose I have been given a special kind of formula food and a syringe. If despite my best efforts to force feed her, she still refuses to take nourishment, I am to go back to the vet's to have her put on a drip tomorrow.
There's a slight chance the ataxia may be caused by a brain tumour, and to show it, there's the option of a CT scan being performed, but it's priced at 700 euros and the vet didn't recommend it at this stage. I can always push for it if Leila doesn't improve in the next few days.
Poor little puss. I've put her in a cardboard box lined with old towels, as the vet's explained that it's best to keep her in a small and confined space for now: it should help keep the nausea to a minimum. I've also called work to let them know I'm taking the rest of the week off to care for my cat.