Feline hyperthyroidism a mystery.

Feline hyperthyroidism a mystery

When an older cat becomes restless, loses weight despiteeating heavily or develops an increased heart rate, it may be suffering from overactive thyroid function, or hyperthyroidism. Scientists in several veterinary research centers across the United States are trying to unravel the cause or causes of what can be a fatal disease if left untreated. Although hyperthyroidism has long been described in humans, the feline form of the disease -- similar pathologically to a rare human type -- apparently is a new disease.

Recent research has focused on environmental factors, suchas food or toxic agents, as potential causes of the disease. As yet, no hard data have confirmed these suspicions or supported observations that the disease is more prevalent in the Northeast. Scientists at Tufts University School of Veterinary Medicine in Boston hope to provide more concrete answers to some of these questions within the next few months.

First noticed by veterinarians in New England in 1980, thedisease affects cats more than 6 years old. Certain cats may develop goiter while retaining normal thyroid function, suggesting that the thyroid gland may enlarge first, leading to secondary hyperthyroidism. Diagnosis is made using a simple blood test; possible treatments include surgical removal or irradiation of the thyroid, with subsequent hormone therapy.