In the United States, 1 in 3 households has a pet cat.

But many aspects of feline health remain a mystery, even to experts.

And when one of our kittens became critically ill last year, no one could explain why.

pet theory

When my husband and I took our cat to the vet early last year, we were hoping to hear that we had nothing to worry about. Olive, a longhaired tortoiseshell kitten who had been the runt of her litter, was naturally quiet and skittish, prone to hiding in closets and napping behind the shower curtain. That made her hard to read — and sometimes simply to find.

But days earlier, we had started wondering whether she might be sick. Did she seem even more reserved than usual? It was hard to say, but we decided to ask her vet just to be safe. The vet immediately noticed that Olive’s gums were pale and that her heart was racing. A quick blood test revealed that she was severely anemic, with a blood-cell volume so low, the vet said, it was “incompatible with life.”

So began a monthslong ordeal featuring repeated visits to the veterinary I.C.U., more than a dozen blood transfusions and few solid answers.

“Cats have been so understudied,” said Elinor Karlsson, a geneticist at UMass Chan Medical School and the Broad Institute. “They’re going to remain a black box unless something changes on the research side.”

Dogs as the default

Over the last few decades, veterinary medicine has made enormous strides, allowing pets like Olive to receive highly advanced care. But feline medicine has lagged behind its canine counterpart, and it is not always easy to provide evidence-based medicine for cats. “It’s still considered a bit of a niche interest,” said Dr. Karen Perry, a veterinary orthopedic surgeon with a focus on feline health at Michigan State University.