Forty years ago, feline hyperthyroidism was virtually nonexistent. Now it’s an epidemic — and some scientists think a class of everyday chemicals might be to blame. By EMILY ANTHES MAY 16, 2017
Most days, the back room of the Animal Endocrine Clinic in Manhattan is home to half a dozen cats convalescing in feline luxury. They lounge in their own individual “condos,” each equipped with a plush bed, a raised perch and a cozy box for hiding. Classical music plinks softly from speakers overhead. A television plays cat-friendly videos — birds chirping, squirrels scampering. Patients can also tune in to the live version: A seed-stuffed bird feeder hangs directly outside each window.
One afternoon in April, a jet-black cat named Nubi assumed a predatory crouch in his condo as a brawny pigeon landed on a feeder. Dr. Mark Peterson, the soft-spoken veterinarian who runs the clinic, opened the door to Nubi’s condo and greeted the 12-year-old tom in a lilting, high-pitched voice. “How are you?” Peterson asked, reaching in to scratch his patient’s soft chin. Nubi, who typically is so temperamental that his owner jokes about needing a priest to perform an exorcism, gently acquiesced, then turned back to the bird. Peterson seemed eager to linger with each of Nubi’s four feline neighbors — Maggie, Biggie, Fiji and Napoleon — but, he warned, “these cats back here are radioactive.”
He meant that literally. The previous day, all five animals received carefully titrated doses of radioactive iodine, designed to destroy the overactive cells that had proliferated in their thyroid glands and flooded their bodies with hormones. These cats are among the millions suffering from hyperthyroidism, one of the most mysterious diseases in veterinary medicine. When Peterson entered veterinary school in 1972, feline hyperthyroidism seemingly didn’t exist; today, he treats nothing else. In the intervening decades, hyperthyroidism somehow became an epidemic in cats, and no one knows why. “I’ve devoted most of my time in the last 35 years to this,” said Peterson, who noted that he has treated more than 10,000 hyperthyroid cats, “and I still have more questions than I have answers.”
Although definitive answers remain elusive, scientists are narrowing in on one possible explanation: A steady drumbeat of research links the strange feline disease to a common class of flame retardants that have blanketed the insides of our homes for decades. But even as the findings may answer one epidemiological question, they raise another in its place. If household chemicals are wreaking havoc on the hormones of cats, what are they doing to us?