In 1980, the number of cats diagnosed with hyperthyroidism was around one in 200. Today, that number is closer to one in 10.
On Monday, thanks to an innovative silicone pet tag developed at Oregon State University, researchers are one step closer to understanding the alarming spike in the feline disease.
The cause might just be embedded in the fibers of your couch.
To study the epidemic, Carolyn Poutasse, a doctoral student in the Oregon State College of Agricultural Sciences, attached silicone tags to the collars of 78 cat, some with hyperthyroid, others without. The specially-made tags, developed at the university, measure exposure to environmental chemicals.
“The tags are porous and chemically very similar to human cells,” Kim Anderson, an environmental chemist who helped create the tags, said in a statement. “Molecules of contaminants embed themselves in the silicone in the same way they’d go into the cells in your body. The silicone is a pretty good mimic of the types of chemicals that you can absorb – what we call passive sampling.”
The animals kept the tags on for a week and their owners filled out a survey. Poutasse found that levels of tris (1,3-dichloro-2-isopropyl) phosphate, a flame retardant commonly referred to as TDCIPP, corresponded with thyroid hormone levels in the cats.
“The way a cat is diagnosed with feline hyperthyroidism is by extremely elevated concentrations of thyroid hormones,” Anderson said. “Seeing the correlation is suggestive of a connection between thyroid function and exposure to TDCIPP.”
The results of the study were recently published in the journal Environmental Science & Technology.
TDCIPP is used to treat foam in some upholstered furniture, plastics and certain types of air fresheners. Demand for the chemical in the U.S. has been on the rise, from 450 tons in 1997 to 22,700 tons in 2006, the researchers said.
In cats, hyperthyroidism is caused by an increase in thyroid hormones and symptoms can include weight loss, increased appetite, vomiting, diarrhea, and hyperactivity. The increased size of the thyroid glands can cause non-cancerous tumors called adenoma. Animals with hyperthyroidism can be treated with medication, radiation therapy or surgery to remove the enlarged glands.
Left untreated, the disease can lead to heart disease and elevated blood pressure.
The tumors caused by hyperthyroidism are identical in humans and cats, leading Anderson to ask whether the chemicals that appear to be causing elevated hormonal levels in felines could have the same effect on people who come into contact with flame retardants. They don’t have an answer yet, but Anderson said the recent findings warranted further study.
“If we follow these cats for five years, would those cats on the higher end of normal thyroid hormone levels continue to progress to have higher and higher levels assuming their exposure to TDCIPP continues to be elevated?” Anderson said. “That would be the natural question if cats end up with hyperthyroidism.”
-- Kale Williams
503-294-4048
Visit subscription.oregonlive.com/newsletters to get Oregonian/OregonLive journalism delivered to your email inbox.