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 EP