The effect of pp'‐DDT on the rate, amplitude and weight of the heart of the pigeon and Bengalese finch

Abstract

Synopsis Fifty‐four homing pigeons were fed control diets and dose rates of pp'‐DDT ranging from 3 to 36 mg/kg d. At 3 mg/kg d there was an increase in the pulse rate and S wave amplitude after 3 weeks dosing followed by an increase in the heart weight. The pulse rate, amplitude and weight then decreased with increasing dose rate. At high dose rates the heart was flaccid and reduced to half the normal weight after 8 weeks. This pattern of results is similar to that obtained for oxygen consumption, body temperature and vitamin A storage, using this species. This suggests that DDT causes hyperthyroidism at low dose rates and hypothyroidism at high dose rates in pigeons. These results contrast with those for the Bengalese finch which suggest hyperthyroidism only. The possible mechanisms and effects of these reactions are discussed.