Since the late 1970’s, there has been a significant increase in the prevalence
of feline hyperthyroidism, making it the most common feline endocrine disorder in
the world. What causes hyperthyroidism, and why is it so common? Previous studies
of cats in the U.S., Great Britain and New Zealand have identified a number of risk
factors for the development of hyperthyroidism, including genetic predispositions,
the feeding of some canned cat foods and cross-breeding. Furthermore, some veterinarians
believe feline hyperthyroidism is simply an outcome of cats living longer. But,
if thyroid dysfunction is symptomatic of old age, why is it not more common in dogs,
or people for that matter?
Veterinarians first noticed a dramatic surge in feline
hyperthyroidism in the 1980’s. This rise coincided with the prevalent use of PBDE’s
as a flame retardant in many products. A chemical flame retardant used widely in
carpet pads, furniture, and electronics, PBDE (or, polybrominated dephenyl ethers)
were researched in a recent EPA study that suggested that these chemicals may partly
explain the current epidemic. PBDE’s linger in the environment, and cats ingest
the substance in both foods and by licking their fur which retains house dust laced
with toxic PBDE particles. Furthermore, studies have also shown a link between hyperthyroidism
and BPA in the lining of many canned cat foods. Life’s Abundance is proud to inform
our consumers that the lining in our canned foods is BPA-free.
Science & Technology study reported in 2007 looked at whether hyperthyroid cats
had greater body burdens of PBDE’s, and found that all cats have high levels compared
to humans, with some cats with incredibly high levels (Dye et. al, 2007). The potential
link between feline hyperthyroidism and PBDE exposure may be the veritable “canary
in the coal mine” when it comes to evaluating the human health impacts of PBDE’s.
People in the United States have the highest PBDE levels reported worldwide, according
to a 2004 study also published in Environmental Science & Technology. By gaining
a more complete understanding of chronic indoor PBDE exposure and its effects on
thyroid hormone levels in cats, medical researchers can better assess whether the
same risk exists for people. Researchers believe that further studies need to be
performed before concluding a direct link between PBDE’s and feline hyperthyroidism.
There is good news, however. It isn’t necessary to rip up your carpet and throw
out your furniture as these chemicals have been or are in the process of being banned
in many states. And cats still live longer, healthier lives if they live primarily
indoors, and the risk of being attacked by other animals or hit by a car while roaming
outside is still much greater than the risk of developing hyperthyroidism from PBDE
What can you do if your cat has already been diagnosed with hyperthyroidism?
What are the symptoms? In this video, Dr. Sarah reviews the signs of hyperthyroidism
and treatments available. If you suspect your kitty has hyperthyroidism, schedule
an appointment with your local veterinarian.
Potera, C. Environews Forum. Chemical
Exposure: Cats as Sentinel Species. Environ Health Perspect. 2007. Dec;115(12)A580.
Wakeling J, Everard A, Brodbelt D, Elliott J, Syme H. Risk factors for feline hyperthyroidism
in the UK. J Small Anim Pract. 2009 Aug;50(8):406-14.