Thyroid Gland Overview
Posted: Monday, October 18th, 2021 | Updated: Monday, February 7th, 2022
Posted: Monday, October 18th, 2021 | Updated: Monday, February 7th, 2022
The Thyroid Gland
The thyroid gland, located on each side of the larynx, consists of two lobes connected by a narrow band called an isthmus. This gland produces thyroid hormone and calcitonin. Thyroid hormone helps regulate the metabolic rate of the body and calcitonin helps regulate the calcium levels in the blood. Thyroid hormone actually includes two hormones; T3 and T4. T4 is known as thyroxine and T3 is triiodothyronine. T4 is mostly converted to T3 before having any effect on the target cells. When thyroid stimulating hormone (TSH) is secreted by the anterior pituitary gland and reaches the thyroid gland, T3 and T4 are produced. Thyroid hormone helps heat the body in cold temperatures by increasing the overall metabolic rate. This increase also causes nutrients to be burned at a faster rate. Proteins, carbohydrates, and lipids are metabolized for energy under these circumstances. Calcitonin helps provide homeostasis of blood calcium levels by telling the body to deposit any excess calcium in the bones. This helps prevent hypercalcemia
Hypothyroidism
Hypothyroidism is a deficiency of the thyroid gland to produce hormones that regulate the metabolic rate. Thus, animals with hypothyroidism have a below normal metabolic rate. In most cases, it's cause is autoimmune related or idiopathic and results in the destruction of the thyroid tissue. Skin and coat changes are most notably seen in these patients prior to diagnosis. Patients experience poor hair regrowth, increased hair loss, and have hair that is overly dry or brittle. Their skin is often dry, thick, and pigmented darkly. Patients may gain weight easier, have an intolerance to the cold, have a slower heart rate, be lethargic, and lack heat cycles. Long term patients may be diagnosed with blepharitis, corneal ulcers, deafness, megaesophagus, constipation, DCM, strokes, von Willebrand's disease, myasthenia gravis, high cholesterol levels, and anemia
Hyperthyroidism
Hyperthyroidism is a result of too much thyroid hormone being produced. This increase in thyroid production speeds up the body's cellular metabolism. Nervousness, weight loss, an increased appetite, a faster heart rate, vomiting, and diarrhea may be seen with this disease process. Polyuria and polydipsia are commonly observed as well. Occasionally, hyperthyroidism may result in a medical emergency. Patients usually present febrile, tachycardic, and hypertensive leading to CHF, pulmonary edema, and collapse
The thyroid gland, located on each side of the larynx, consists of two lobes connected by a narrow band called an isthmus. This gland produces thyroid hormone and calcitonin. Thyroid hormone helps regulate the metabolic rate of the body and calcitonin helps regulate the calcium levels in the blood. Thyroid hormone actually includes two hormones; T3 and T4. T4 is known as thyroxine and T3 is triiodothyronine. T4 is mostly converted to T3 before having any effect on the target cells. When thyroid stimulating hormone (TSH) is secreted by the anterior pituitary gland and reaches the thyroid gland, T3 and T4 are produced. Thyroid hormone helps heat the body in cold temperatures by increasing the overall metabolic rate. This increase also causes nutrients to be burned at a faster rate. Proteins, carbohydrates, and lipids are metabolized for energy under these circumstances. Calcitonin helps provide homeostasis of blood calcium levels by telling the body to deposit any excess calcium in the bones. This helps prevent hypercalcemia
Hypothyroidism
Hypothyroidism is a deficiency of the thyroid gland to produce hormones that regulate the metabolic rate. Thus, animals with hypothyroidism have a below normal metabolic rate. In most cases, it's cause is autoimmune related or idiopathic and results in the destruction of the thyroid tissue. Skin and coat changes are most notably seen in these patients prior to diagnosis. Patients experience poor hair regrowth, increased hair loss, and have hair that is overly dry or brittle. Their skin is often dry, thick, and pigmented darkly. Patients may gain weight easier, have an intolerance to the cold, have a slower heart rate, be lethargic, and lack heat cycles. Long term patients may be diagnosed with blepharitis, corneal ulcers, deafness, megaesophagus, constipation, DCM, strokes, von Willebrand's disease, myasthenia gravis, high cholesterol levels, and anemia
Hyperthyroidism
Hyperthyroidism is a result of too much thyroid hormone being produced. This increase in thyroid production speeds up the body's cellular metabolism. Nervousness, weight loss, an increased appetite, a faster heart rate, vomiting, and diarrhea may be seen with this disease process. Polyuria and polydipsia are commonly observed as well. Occasionally, hyperthyroidism may result in a medical emergency. Patients usually present febrile, tachycardic, and hypertensive leading to CHF, pulmonary edema, and collapse
Sources:
Colville, Thomas, and Joanna M. Bassert. Clinical Anatomy and Physiology for Veterinary Technicians. 2nd ed. Mosby Elsevier, 2008.
Giffin, James M. and Lisa D. Carlson. Dog Owner's Home Veterinary Handbook. 3rd ed. Hungry Minds, Inc. 2000.
Kahn, Cynthia M. The Merck/Merial Manual for Pet Health. Home Ed. Merck & Co., Inc. 2007.
Colville, Thomas, and Joanna M. Bassert. Clinical Anatomy and Physiology for Veterinary Technicians. 2nd ed. Mosby Elsevier, 2008.
Giffin, James M. and Lisa D. Carlson. Dog Owner's Home Veterinary Handbook. 3rd ed. Hungry Minds, Inc. 2000.
Kahn, Cynthia M. The Merck/Merial Manual for Pet Health. Home Ed. Merck & Co., Inc. 2007.