Autonomous hypersecretion due to hyperactivity (primary hyperfunction) of an endocrine gland can be due to what two things?
- Hyperplasia of gland
Secondary hyperfunction in an endocrine gland is usually due to what?
Lesion in one organ secreting excess trophic hormone leading to excess stimulation of target organ
Excess secretion of peptides similar to hormones causing hyperactivity can be caused by what?
Non-endocrine neoplasms (Adenocarcinoma or anal sacs)
What are some examples of iatrogenic syndromes of hormone excess?
- Corticosteroid administration
- Excessive insulin
- Excess T4 and T3
- Progestogens to dogs
What are three possibilities responsible for primary hypofunction of an endocrine gland?
- Destruction of secretory cells
- Failure of development
- Genetic/biochemical defect
What can be due to secondary hypofunction of an endocrine gland?
Lesion in one organ interfering with the secretion of of trophic hormone
What are two explanations for endocrine dysfunction due to failure of target-cell response?
- Alteration in hormone receptors on the cell surface
- Lack of adenyl cyclase in the cell membrane
In what breeds of dogs is it common to find pituitary cysts and pituitary dwarfism?
- German shepherd dog
- Toy pinscher
- Carelian bear dog
What is pituitary cysts and pituitary dwarfism due to?
Failure of the oropharyngeal ectoderm of Rathke's pouch to differentiate into the pars distalis
What lesions are associated with pituitary cysts and dwarfism?
- Multiloculated cyst in the sella turcica
- Absence of the adenohypophysis
What clinical signs are associated with pituitary cysts and dwarfism?
- Slower growth and stunting
- Bilaterally symmetric alopecia
- Progressive hyperpigmentation of the skin
If a tumor is producing trophic hormones that stimulate target organs, how is it described?
If a tumor is destructive to adjacent structures causing hypoactivity of an endocrine gland, how is it described?
What are the most common endocrine gland tumors of adults?
Adenomas and carcinomas
What are the most common endocrine tumors of younger animals?
What is the most common pituitary neoplasm in horses?
Adenoma of the pars intermedia
What is the second most common pituitary neoplasm of the dog?
Adenoma of the pars intermedia
What functionally active tumor is derived from corticotroph cells in the pars distalis or the pars intermedia of dogs and is common in adult aged boxers, boston terriers and dachshunds?
ACTH-secreting (corticotroph) adenoma (results in Cushing's disease)
In what animals is endocrinologically inactive chromophobe adenoma usually seen in?
- Laboratory rodents
What clinical signs are associated with endocrinologically inactive chromophobe adenoma?
- Decreased spontaneous activity
- Weakness and collapse after exercise
- blindness and dilated, fixed pupils
What benign tumor is derived from the epithelial remnants of Rathke's pouch and causes abnormal secretion of somatotropin (growth hormone)?
Craniopharyngioma (intracranial germ cell tumor)
What clinical signs are associated with craniopharyngioma (intracranial germ cell tumor)?
- Failure to attain somatic maturation
- Interference with release and synthesis of ADH
- Deficits in cranial nerve function
What type of inflammation is seen sporadically in ruminants and swine?
What is the etiology behind pituitary abscesses, common in ruminants and swine?
- Arcanobacterium pyogenes
- Mycotic agents
What can a lesion in the neurohypophysis that interferes with ADH synthesis or secretion cause?
Central diabetes insipidus
What form of diabetes insipidus is a hereditary defect resulting in lack of adenylate cyclase in the plasma membrane of epithelial cells in the distal tubules and collecting ducts?
Hemorrhage of the adrenal cortex can be due to what three things?
- Trauma in newborn
- Severe stress
What syndrome of the adrenal cortex is usually a fatal consequence of overwhelming sepsis but can also be due gram-positive organisms, anticoagulant therapy and trauma?
In what animals is nodular hyperplasia of the adrenal cortex seen in?
- Old horses
- Female ferrets
What is the result of nodular hyperplasia of the adrenal cortex?
- Androgen excess leading to:
- Greater muscle mass
- Well-developed crest
- Hypertrophy of the clitoris
- Involution of the mammary gland
In what animals are cortical adenomas of the adrenal cortex seen in?
- Older dogs
- Castrated male goats
- Neutered ferrets
In what hyperplasia/neoplasia of the adrenal cortex do you see multiple small foci, usually bilateral and without encapsulation?
In what hyperplasia/neoplasia of the adrenal cortex do you see larger, unilateral and encapsulated growths?
In what animals are coritcal carcinomas usually seen in?
What type of tumor of the adrenal cortex is larger than adenomas, often bilateral, and may invade the vena cava?
What is the second most common neoplasm reported in adult ferrets?
Adrenal gland neoplasms
What clinical signs are associated with functional proliferative lesions in ferrets?
- Vulvular enlargement
- Bilaterally symmetrical alopecia
- Increased plasma concentrations of estradiol-17B
What percent of Cushing's disease is due to primary hyperadrenocorticism?
What percent of the Cushing's disease is due to secondary hyperadrenocorticism?
What percent of Cushing's disease is due to pharmacological (iatrogenic) hyperadrenocorticism?
What possible pathogenetic mechanisms can cause Cushing's disease?
- Primary hyperadrenocorticism
- Secondary hyperadrenocorticism
- Pharmacological (iatrogenic) hyperadrenocorticism
- Ectopic ACTH syndrome
What clinical signs are associated with Cushing's disease (hypercortisolism)?
- Pendulous abdomen
- Skin lesions
- Bilateral symmetric alopecia
- Calcinosis cutis
- Eosinopenia and lymphopenia
What are some pathogenetic mechanisms responsible for primary hypoadrenocorticism?
- Bilateral idiopathic adrenal cortical atrophy
- Bilateral destruction of adrenal glands
What primary hypoadrenocorticism involves the destruction of all three cortical layers, a deficiency in production of all cortical hormones, and is see most frequently in young to middle-aged female dogs?
Bilateral idiopathic adrenal cortical atrophy
What primary hypoadrenocorticism is due to adrenalitis, infarction, hemorrhage and tumors?
Bilateral destruction of adrenal glands
What type of primary hypoadrenocorticism involves sudden withdrawal following prolonged excessive administration of synthetic steroids?
What must be done for a dog to usually get Addison's disease (hypoadrenocorticism)?
All three layers of the adrenal gland are destroyed
ACTH deficiency from a destructive pituitary lesion usually only leads to which two zones in the adrenal gland to be destroyed (mineralocorticoids are not affected)?
- Zona fasciculata
- Zona reticularis
What clinical signs are usually seen with hypoadrenocorticism?
- Stress intolerance
- Hyponatremia and hyperkalemia
- Hypernaturia and hyperchoriduria
- Skin may be hyperpigmented
What is the most common neoplasm of the adrenal medulla in animals?
In which animals i pheochromocytoma usually seen?
What pathogenetic mechanisms can cause goiter (hyperplasia of the thyroid gland)?
- Iodine deficient diet
- Excess dietary iodide
- Goitrogenic compounds (Brassica and Cruciferae plants)
- Genetic enzyme defects
What type of goiter do you see in young adult and adult animals following the correction of the problem in diffuse hyperplastic goiter?
What type of goiter do you see in young animals born to dams on iodine deficient diet or excess iodine, fed goitrogenic substances or plants of Brassicacceae family?
Diffuse hyperplastic goiter
What type of goiter is an incidental lesion in old animals (horses, cats, and dogs) and is nonfunctional in most animals except cats?
Multifocal nodular hyperplasia
What type of goiter is the result of an autosomal recessive disorder in some breeds of sheep, Afrikander cattle, and Saanen dwarf goats?
Congenital dyshormonogenetic goiter