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Changes
→Consequences of Iodine Deficiency
#'''Thyroid changes''': In a long-term feeding trial of dogs receiving low dietary levels of iodine (0.3 mg/kg dry matter – DM), thyroid glands became hyperplastic and hypertrophic during the first 9 months. Significant increases in the thyroid uptake of radiolabelled iodine were also reported<ref>Norris, C, Fritz, T, Taylor, J (1970). “Cycle of accommodation to restricted dietary iodide in thyroid gland of the beagle dog”. Am. J. Vet. Res. 31:21-33.</ref>. However, the dogs seemed to adapt as the study progressed beyond 9 months because the thyroid glands eventually returned to normal size and appearance.
#'''Thyroid changes''': In a long-term feeding trial of dogs receiving low dietary levels of iodine (0.3 mg/kg dry matter – DM), thyroid glands became hyperplastic and hypertrophic during the first 9 months. Significant increases in the thyroid uptake of radiolabelled iodine were also reported<ref>Norris, C, Fritz, T, Taylor, J (1970). “Cycle of accommodation to restricted dietary iodide in thyroid gland of the beagle dog”. Am. J. Vet. Res. 31:21-33.</ref>. However, the dogs seemed to adapt as the study progressed beyond 9 months because the thyroid glands eventually returned to normal size and appearance.
#'''Serum levels of thyroid hormones''': When adult beagles were fed very low intakes of iodine (50 or 20 µg/day, equivalent to a dietary iodine content of about 0.27 and 0.11 mg/kg DM respectively) marked reductions in serum T<sub>4</sub> but not T<sub>3</sub> were observed<ref>Belshaw, BE, Cooper TB, Becker Jr. DV (1975). “The iodine requirement and influence of iodine intake on iodine metabolism and thyroid function in the adult beagle”. Endocrinology 96:1280-1291.</ref>.
#'''Serum levels of thyroid hormones''': When adult beagles were fed very low intakes of iodine (50 or 20 µg/day, equivalent to a dietary iodine content of about 0.27 and 0.11 mg/kg DM respectively) marked reductions in serum T<sub>4</sub> but not T<sub>3</sub> were observed<ref>Belshaw, BE, Cooper TB, Becker Jr. DV (1975). “The iodine requirement and influence of iodine intake on iodine metabolism and thyroid function in the adult beagle”. Endocrinology 96:1280-1291.</ref>.
#''''Goitre and other clinical signs''': In dogs fed low iodine levels primarily as a result of receiving an all-meat diet, signs consisted of goitre (enlargement of the thyroid gland), weight gain and adverse effects on hair condition<ref>Thompson, T (1979). “Iodine-deficiency goitre in a bitch”. New Zealand Vet. J. 27:113.</ref><ref>Nuttall, W (1986). “Iodine deficiency in working dogs”. New Zealand Vet. J. 34:72.</ref>.
#'''Goitre and other clinical signs''': In dogs fed low iodine levels primarily as a result of receiving an all-meat diet, signs consisted of goitre (enlargement of the thyroid gland), weight gain and adverse effects on hair condition<ref>Thompson, T (1979). “Iodine-deficiency goitre in a bitch”. New Zealand Vet. J. 27:113.</ref><ref>Nuttall, W (1986). “Iodine deficiency in working dogs”. New Zealand Vet. J. 34:72.</ref>.
====Cat:====
====Cat:====
There is little information on iodine deficiency in the cat but one study identified changes to the thyroid gland linked to a low iodine diet.
There is little information on iodine deficiency in the cat but one study identified changes to the thyroid gland linked to a low iodine diet.