Edinboro C, Scott-Moncrieff C, Tetrick M, Glickman L.
School of Veterinary Medicine, Purdue University, West Lafayette, IN, USA
PURPOSE: The prevalence of hyperthyroidism in pet cats (benign nodular
hyperplasia) has reached epidemic proportions, since it was first described in
1979. Therefore, we tested the hypothesis that consumption of canned foods
compared with dry foods increases the risk of hyperthyroidism. Furthermore,
the risk associated with lower iodine concentrations in canned foods and
chemicals in can linings was evaluated. Secondary hypotheses were that
hyperthyroid risk is increased by well water consumption and exposure to
environmental endocrine disrupters.METHODS: Case cats (n = 109) had serum
T4 concentration >/=5.0 &mgr;g/dl and >/=1 clinical sign of hyperthyroidism;
control cats (n = 173) had a serum T4 concentration /=50% canned: OR = 3.45, 95% CI: 1.77,
6.74; <50% canned: OR = 2.84, 95% CI: 1.48, 5.46). Other significant risk
factors were use of cans with easy-open lids (vs. dry) (OR = 3.79, 95% CI:
1.68, 8.54), foods without iodine supplementation in any life stage (OR = 4.09,
95% CI: 1.09, 15.40), years of well water consumption (OR = 1.12, 95% CI:
1.02, 1.23), years of exposure to gas fireplaces (OR = 1.16, 95% CI: 1.02,
1.31), age (OR = 1.15, 95% CI: 1.03, 1.29), and female gender (OR = 2.73,
95% CI: 1.38, 5.43).CONCLUSIONS: Endocrine disrupters in food can
linings and the environment may explain the recent epidemic of
hyperthyroidism in cats, since easy-open cans have gained popularity. This
same relationship should also be evaluated in humans.