Diagnosis is made through case history, serology, glucose tolerance testing and the elimination of Cushing’s disease as the cause of symptoms. Treatment includes strict weight control through diet and a controlled exercise program that regulated daily exercise.
Disorders of the Thyroid Gland The thyroid gland is located caudal to the larynx. It produces two hormones, thyroxine (T4) and triiodothyronine (T3), which regulate the body’s . The thyroid hormones are the only iodonated organic compounds in the body, meaning that is an essential part of the thyroid hormones. T3 and T4 production is stimulated by the hormone thyroid stimulating hormone (TSH) which is secreted by the pituitary gland.
Hypothyroidism
Hypothyroidism is a disease characterized by a decrease in the production and secretion of thyroid hormones. It can be caused by dysfunction of the thyroid gland, breakdown of the hypothalamus-pituitary axis, or by a deficiency in iodine. Without sufficient stimulation from the pituitary in the form of TSH the thyroid gland produces less of the thyroid hormones. If this situation persists for some time the thyroid gland will as fewer cells are required to be functional. Once the gland has atrophied it may not be able to return to previous levels of hormone production and secretion and may not be able to produce sufficient amounts of hormone to maintain normal metabolic rate. Another cause of hypothyroidism is the insufficient intake of dietary iodine. This causes the thyroid gland to as the gland attempts to filter iodine out of the blood more efficiently by increasing its mass and its vasculature. Increased blood flow to the thyroid results in inflammation of the gland tissue which impairs the production of thyroid hormones even if iodine levels become adequate.
, horses fed forage grown in iodine deficient soils and horses fed goitrogenic plants
such as soy are predisposed to hypothyroidism.
The clinical presentation of hypothyroidism includes formation, lethargy, anorexia, sluggishness, weight gain, fatty deposits in the crest, exercise intolerance, thinning haircoat, cold intolerance, laminitis and the development of myopathies.
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