Lecture 18 4/25/25

Question 1

What is the most common pathological cause of endocrine disorders?

Answer 1

disorders of growth, including atrophy, hyperplasia, and neoplasia

Question 2

What are the characteristics of hypothalamus anatomy and physiology?

Answer 2

-continuous with posterior pituitary pars nervosa
-loss of ADH production leads to central diabetes insipidus
-patients experience loss of ADH-mediated urine conc. and diuresis

Question 3

What are the main components of the pituitary gland?

Answer 3

*anterior pituitary
-pars intermedia
-pars distalis
*posterior pituitary
-pars nervosa

Question 4

Which hormones are produced by each part of the pituitary gland?

Answer 4

-pars intermedia: MSH
-pars distalis: ACTH, GH, TSH, LTH, FSH, LH
-pars nervosa: ADH, oxytocin

Question 5

What are the characteristics of pituitary dwarfism?

Answer 5

-rare
-main breed is GSDs
-lesion involved is a pituitary cyst in place of the anterior pituitary
-pathogenesis is developmental anomaly of Rathke’s pouch

Question 6

What are the consequences of pituitary dwarfism?

Answer 6

-no GH: symmetrical dwarfism
-no ACTH: Addison’s dz
-no TSH: hypothyroidism

Question 7

What are the characteristics of pituitary abscesses?

Answer 7

-seen in ruminants, especially males
-can form from hematogenous spread with bacteremia or extension of infection in adjacent tissue
-various bacteria possible

Question 8

What are the characteristics of pituitary neoplasms?

Answer 8

*typically adenomas
*pars distalis can see the following types:
-corticotroph/ACTH-secreting
-somatotroph/GH-secreting
-nonfunctional
*can also occur in pars intermedia

Question 9

What are the characteristics of corticotroph/ACTH-secreting adenomas?

Answer 9

-seen in dogs
-results in bilateral adrenocortical hyperplasia
-leads to hypercortisolism and pituitary dependent/secondary hyperadrenocorticism

Question 10

What are the characteristics of somatotroph/GH-secreting adenomas?

Answer 10

-seen in cats
-rare
-leads to hypersomatotropism, resulting in acromegaly and diabetes mellitus

Question 11

What are the clinical features of acromegaly?

Answer 11

-broad facial features
-prognathia inferior
-enlarged paws

Question 12

What are the characteristics of pars intermedia neoplasms?

Answer 12

-can be hyperplasia or adenoma
-cause equine pituitary pars intermedia dysfunction/PPID
-common in older horses and ponies

Question 13

What are the consequences of hypothalamic dysfunction and Pro-OMC peptides in PPID?

Answer 13

-hirsutism/long, shaggy hair coat
-insulin resistance
-adiposity
-laminitis

Question 14

What is the normal ratio of adrenal cortex to adrenal medulla?

Answer 14

1:1

Question 15

What are the three zones of the adrenal cortex and their hormones produced?

Answer 15

-zona glomerulosa: mineralocorticoids
-zona fasciculata: glucocorticoids
-zona reticularis: sex hormones

Question 16

Which hormones stimulate the adrenal cortex?

Answer 16

-ACTH (stimulates all zones, primarily ZF)
-renin/angiotensin (stimulates ZG only)

Question 17

What are the characteristics of adrenal cortex nodular hyperplasia?

Answer 17

-old age change of many species
-not clinically significant; incidental finding

Question 18

What are the characteristics of adrenal cortex diffuse hyperplasia?

Answer 18

-consequence of ACTH-secreting pituitary adenoma
-finding in pituitary-dependent/secondary hyperadrenocorticism

Question 19

What are the types of neoplasia affecting the adrenal cortex?

Answer 19

-cortisol-producing
-sex hormone-producing
-nonfunctional

Question 20

What are the characteristics of cortisol-producing adrenal cortex neoplasms?

Answer 20

-seen in dogs
-lesions underlie adrenal-dependent/primary hyperadrenocorticism
-50% are adenomas, 50% are carcinomas

Question 21

What is the appearance of the adrenal glands in iatrogenic cushing’s?

Answer 21

atrophied cortex; no need to produce hormones because they are being provided

Question 22

Which lesions are associated with each type of cushing’s?

Answer 22

*pituitary-dependent/secondary:
-ACTH-secreting pituitary adenoma
-adrenocortical hyperplasia

*adrenal-dependent/primary:
-cortisol-producing adrenocortical neoplasm

*iatrogenic:
-adrenocortical atrophy

Question 23

What are the consequences of hyperadrenocorticism?

Answer 23

-pendulous abdomen
-steroid hepatopathy
-bilaterally symmetrical alopecia
-calcinosis cutis
-lesions of immunosuppression

Question 24

What are the common sites of secondary infection in cushing’s animals?

Answer 24

-skin
-ears
-urinary bladder
-oral cavity

Question 25

What are the characteristics of sex hormone-producing adrenal cortex neoplasms?

Answer 25

-common in ferrets, esp. females -hyperplasia most common; then carcinoma; then adenoma -early neutering leads to chronic stimulation of ZR by LH

Question 26

What are the consequences of hyperestrogenism?

Answer 26

-alopecia -vulvar enlargement -endometrial hyperplasia (females) -prostatic squamous metaplasia (males) -bone marrow hypoplasia and anemia

Question 27

What does adrenal cortex atrophy lead to?

Answer 27

hypoadrenocorticism/Addison's

Question 28

What are the possible pathogeneses of hypoadrenocorticism?

Answer 28

*primary/idiopathic: -young adult dogs -may have lymphocytic adrenalitis early on; later just atrophy *iatrogenic: -abrupt cessation of exogenous corticosteroids OR -mitotane/trilostane over-treatment *secondary: -loss of CRH/ACTH due to brain lesion

Question 29

How does primary Addison's differ from secondary Addison's?

Answer 29

*primary: -affects all three cortex layers -deficient in mineralocorticoids and glucocorticoids *secondary: -impacts ZF primarily -deficient only in glucocorticoids

Question 30

What is produced by the adrenal medulla?

Answer 30

catecholamines; epinephrine > norepinephrine

Question 31

What are the characteristics of pheochromocytoma?

Answer 31

-seen in dogs, bulls, and horses -gross appearance of a grey/brown mottled red tumor -rarely functional -functional tumors lead to tachycardia and cardiac hypertrophy/myonecrosis