Our token black cat Bastet has matching bald spots on both sides, following a visit to the vet today. She's had occasional coughing spells and unwarranted panting for some months, so we finally took her in for an exam. An X-ray found fluid around the lungs, so she got shaved, then drained like a boxed wine at a frat party.
The fluid's been sent off for testing, so we'll have a better idea of possible diagnosis in a few days.
Our Siamese, Tyr, had an interesting reaction when Bastet wasn't brought back to the house right away; he went around the house with his back arched, tail fluffed, and a wild look in his eyes. "Am I next? AM I NEXT?"