One cause identified in surge of feline hyperthyroidism
- One cause identified in surge of feline hyperthyroidism
Albany Times-Union Friday, August 24, 2007
Sick cats sound human alarm
Feline hyperthyroidism linked to household chemical that may be
harmful to people, especially kids
By BRIAN NEARING, Staff writer
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GUILDERLAND -- Dr. Kelly Cooper sees a lot of cats with the telltale
symptoms. They are hungry all the time, drop weight no matter how much
they eat and can't get enough water.
Feline hyperthyroidism almost unknown in cats as recently as the 1970s
is now practically an epidemic, and a new study points to a link with
a toxic chemical flame retardant common in U.S. homes. It may
potentially harm the liver and nervous system and pose a risk to
humans, especially youngsters, though experts say more study is needed.
The nation's most numerous pet, which served as a sentinel in the
recent tainted pet food scandal, also may be the canary in the coal
mine for the health risk linked to the flame retardant, according to a
study this month by the U.S. Environmental Protection Agency, Indiana
University and the University of Georgia.
"We probably have three cats a day coming in that have the disease"
said Cooper, who practices at the Just Cats Veterinary Clinic in
Guilderland. "About 30 to 50 percent of our cats over age 10 are
dealing with it."
Polybrominated diphenyl ethers, or PBDEs, which slow the rate of fire
ignition and growth, have been used since the late 1970s in items like
furniture, carpet padding, computers and cellphones.
The constant grooming cats do is likely causing them to swallow
PBDE-tainted household dust, according to the study, which was
published in the peer-reviewed journal Environmental Science and
Of 23 house cats included in the study, 11 had hyperthyroidism, with
some cats having PBDE blood levels from 20 to 100 times higher than
normal human level in previous North American studies. The liver of a
cat is less effective at detoxification than those of other animals,
including humans and dogs.
The EPA study also raised questions about risks to children, who are
more prone than adults to place household objects in their mouths.
Cats and human beings are the only mammals with a high rate of
hyperthyroidism, although in cats, the condition is most often linked
to a tumor, while in humans, it is usually caused by an immune disorder.
Hyperthyroidism is overactivity of the thyroid, a gland that regulates
the body's metabolic rate. It is treatable in cats through medication,
radiation therapy or surgery.
"It is very concerning that cats and humans have high levels of PBDEs
in their bodies and we need to study it further," said Dr. Louise
Murray, director of medicine at the American Society for the
Prevention of Cruelty to Animals.
While the study raises questions, Murray said that it is difficult to
know whether better veterinary care and testing rather than a surge in
the illness is behind the increased number of reported cases in recent
"Cats are now routinely tested for this, even if they have just lost a
couple of ounces of weight," said Murray. Regardless, it is not known
what causes the illness or the tumor that sparks it, she said.
In 2004, the sole U.S. manufacturer of the types of PBDEs included in
the study agreed to phase out production because of concern about
toxicity in animals, but many homes have items that contain the chemical.
EPA's Web site reports "growing evidence that PBDEs persist in the
environment and accumulate in living organisms" and may damage the
thyroid, liver and nervous system.
"The sudden emergence of feline hyperthyroidism is one of the major
mysteries of the last 30 years in veterinary medicine," said Richard
Goldstein, associate professor of small animal medicine at Cornell
"There was almost no feline hyperthyroidism prior to the 1970s, and
what cases there usually happened from a thyroid tumor," he said. "Now
it is the most common endocrine disease in cats."
"After being found in the U.S., it wasn't in Europe at all, and then
it started to show up. It became common in different areas at
different times, and came late to some areas, like central Europe,"
Previous studies have found links between indoor dust exposure and
PBDE levels in first-time mothers in the Boston area. Another found
PBDE levels in Americans are three to 10 times higher than in
Europeans. And small studies in California and Norway show that
children have higher PBDE levels than adults.
In 2004, the European Union banned two types of PBDEs because of
health concerns, and is studying the remaining type before taking any
This spring, Washington became the first state to ban the use of all
forms of PBDEs in mattresses beginning next year. A ban on their use
in televisions, computers and residential furniture will be enacted in
2011 provided a safer, technically feasible substitute is found for
making the items fireproof.
Nearing can be reached at 454-5094 or by e-mail at