The caudal lobe is called the , and is responsible for the release of antidiuretic hormone (ADH)/vasopressin and oxytocin. All the hormones that are secreted by the pituitary gland are produced in the hypothalamus, and many of these hormones act to control the function of other glands in the body.
Cushing’s Disease
Cushing’s disease is a state of where there is over stimulation of the adrenal glands by the pituitary hormone adrenocorticotropic hormone (ACTH) which causes the increased secretion of . of the ACTH secreting cells of the pituitary gland are known to cause an increase in ACTH secretion, and therefore are known to cause hyperadrenocortisim. 2. Decreased production of the neurotransmitter has been shown to be related to the hypertrophy of the pituitary. There are 2 known causes of Cushing’s: 1. Adenoma of the pituitary or Dopamine acts to suppress the function of a section of the adenohypophysis called the pars intermedia. When dopamine levels are suppressed by oxidative damage of the hypothalamus, pituitary function increases causing the gland to become hypertrophic. Adenoma may also result in hypertrophy of the pars intermedia. The hypertrophic pars intermedia secretes excessive amounts of the hormones ACTH and melanocyte stimulating hormone (MSH) into circulation. An increase in the circulating levels of ACTH stimulates the adrenal gland to produce and secrete increased amounts of cortisol into the blood.
Geriatric horses, ponies and
horses are predisposed to hyperadrenocortisim.
The clinical presentation of Cushing’s disease includes weight loss, muscle wasting, abnormal shedding patterns, , lethargy, weakness, hyperlordosis, bloated abdomen or “hay belly”, polydipsia, polyuria, laminitis, chronic infections and insulin resistance. Diagnosis is made through case history, clinical signs and symptoms, serology showing leukemia, hyperglycemia and increased circulating cortisol, positive ACTH-stimulation test and negative dexamethasone suppression test.
Treatment is primarily
including the administration of IV fluids and daily
low-dose corticosteroid therapy. The commonly used drug is called
.
Prognosis for long term survival is poor.
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