Endocrine Flashcards
A pituitary cyst may cause what disease?
Juvenile Panhypopituitarism (Pituitary Dwarfism)
What breeds are predisposed to Juvenile Panhypopituitarism (Pituitary Dwarfism)?
Brachycephalic breeds German Shepherds Spitz Toy Pinschers Karleian Bear dogs
How is pituitary dwarfism inherited in cats?
Autosomal recessive
Slower growth rate, retention of puppy coat, lack of primary guard hairs, bilaterally symmetrical alopecia are all signs of what disease?
Juvenile Panhypopituitarism (Pituitary Dawrfism)
What are examples of neoplastic diseases of the pituitary?
Corticotrophic (ACTH-secreting) adenoma
Pars intermedia (melanotroph) adenoma
Somatotroph adenoma
For corticotrophic (ACTH-secreting) adenomas, is the size of the tumor related to the severity of the disease?
No
But, larger tumors may cause compression and lead to CNS signs, diabetes insipidus, blindness
What breeds are predisposed to having corticotrophic (ATCH-secreting) adenomas?
Bostons
Boxers
Dachshunds
What is the most common pituitary tumor in horses?
Pars intermedia (melanotroph) adenoma (PPID)
Older horses
Females > males
How do pars intermedia (melanotroph) adenomas present clinically in horses?
Pu/PD, laminitis, increased appetite, muscle weakness, somnolence, intermittent pyrexia, hyperhidrosis, hyper glycemia, glucosuria, hypertrichosis/hirsutism (failure of seasonal shedding)
What disease is caused by somatotroph adenomas?
Acromegaly
Characterized by overgrowth of connective tissue, increased appositional growth of bone, coarsening of facial features, gingival hyperplasia, increased separation of teeth, macroglossia, enlargement of viscera
What disease is a predisposing cause of insulin-resistant diabetes mellitus in cats?
Acromegaly (caused by somatotroph adenomas)
What are the two forms of diabetes insipidus? What are the clinical signs?
Hypophyseal form - inadequate ADH
Nephrogenic form - target cell defect
Clinical signs: PU/PD, hypoosmotic urine
What are the ACTH dependent regions of the adrenal gland?
Zona fasiculata (glucocorticoids)
Zona reticularis (sex steroids)
What are the zones of the adrenal gland and what does each zone produce?
Glomerulosa- aldosterone
Fasiculata- glucocorticoids
Reticularis- sex steroids
Medulla- catecholmines
What is a normal adrenal gland cortical:medullary ratio
1:1 to 2:1
What causes adrenal cortical hyperplasia and what sequelae results from this disease?
Cause: excessive ACTH from functional pituitary adenoma
Sequelae: hyperadrenocorticism (Cushing’s)
If on necropsy you find an animal with diffuse bilateral adrenal cortical hyperplasia, what you might suspect the animal has?
Pituitary adenoma
If on necropsy you find a single, unilateral, well-demarcated, enlarged adrenal gland with atrophy of the contralateral adrenal, what would you suspect?
Adrenal cortical adenoma
How might you differentiate an adrenal adenoma from adrenal carcinoma?
Carcinomas- older dogs, larger than adenomas, can be bilateral
What would cause hyperadrenocorticism?
- Functional ACTH-producing pituitary adenoma
- Functional adrenocortical adenoma or carcinoma
- Idiopathic hyperplasia of adrenal cortex
- Iatrogenic from chronic corticosteriod administration
What causes bilateral adrenal atrophy?
Iatrogenic hyperadrenocorticism (cushing’s)
What pathologies are seen as a result of hyperadrenocorticism (Cushing’s)?
Hepatomegaly Delayed wound healing Frequent infections Increased appetite CNS signs Muscle wasting Alopecia Calcinosis cutis
What clinical pathology is associated with hyperadrenocorticism (cushing’s)?
Neutrophilia without L shift
Lymphopeia
Eosinopenia
Monocytosis
Elevated glucose
Elevated ALP
Low urine SG
What is the main clinical sign of hyperadrenocorticism in cats?
Skin fragility
What causes hypoadrenalcorticism (Addison’s)?
Idiopathic adrenocortical atrophy
Immune -mediated destruction
Abrupt cessation of long-term steroids
What clinical signs are associated with hypoadrenocorticism?
Weight-loss
Non-specific gastroenteritis
Impaired stress tolerance
Hypotensive shock
What clinical pathology is associated with hypoadrenocorticism (Addison’s)?
High K
Low Na+ and Cl-
Eosinophilia
Lymphocytosis
What gross lesions are assictaed with hypoadrenocorticism (addison’s)?
Adrenal cortical atrophy, diffuse bilateral
Lymphoplasmaytic infiltrates
What Na+/K+ ratio is highly suggestive of hypoadrenocirticism (addison’s)?
1:23
What is the most common neoplasia of the adrenal medulla?
Pheochromocytoma
What lesions are a result of functional pheochromocytoma?
Catecholamine overproduction
Edema
Cardiac hypertrophy
What can cause adrenal hemorrhage?
Birth trauma
Exhaustion phase of the “stress response”
Toxemia
Spticemia
Where are ectopic thyroid tissue nodules commonly found in dogs?
Ascending aorta at the base of the heart
Where is thyroid carcinoma commonly found in dogs?
Mediastinum/heart base
Ectopic thyroid tissue that has migrated
What are thyroglossal duct cysts?
Cysts formed from thyroglossal duct remnants seen along the ventral midline of neck
Contain watery to mucoid secretions
Can become inflamed, rupture, and form fistulous tracts to skin
What is goiter?
Non-neoplastic enlargement of the thyroid gland as a result of follicular cell hyperplasia
Diffuse = TSH-induced Multinodular = TSH independent
What causes goiter?
Iodine deficiency
Iodine excess
Goitrogens
Defects in the synthesis of hormones (congenital dyshormonogenic goiter)
Diffuse, bilaterally, enlarged and reddened thyroid glands are indicative of what?
Iodine deficiency goiter
What are goitrogens?
Compounds that cause hyperplastic goiter
Include plants, drugs, or excess iodine
How does colloid goiter cause follicular atrophy?
Cause by involution after repletion of dietary iodine deficiency
Thyroid gland remains enlarged but follicular cells have undergone atrophy because of decreased TSH
What is the most common form of hypothyroidism?
Acquired, Primary
What causes canine hypothyroidism?
Idiopathic follicular atrophy
Lymphocytic thyroiditis
What are the gross lesions associated with with idiopathic follicular atrophy?
Shrunken and pale thyroid gland
Most parenchyma lost or replaced by adipose tissue
What is lymphoplasmacytic thyroiditis?
Auto-immune disease that causes infiltration of thyroid-reactive lymphocytes
Triggered by genetic and environmental factors
A discrete, tan nodule on the thyroid found more commonly in cats than dogs and are often functional is probably what?
Follicular adenoma
A thyroid tumor mainly diagnosed in dogs that is typically invasive, nonfunctional, and arises from ectopic thyroid tissue is probably what?
Thyroid carcinoma
Dairy bulls fed a high calcium diet are prone to what?
Thyroid C-cell hyperplasia and neoplasia
What is the most common equine thyroid tumor?
C-cell adenoma
Thyroid C-cell carcinoma is most commonly found in what species?
Dogs and bulls
How many parathyroid glands do pigs, cattle, sheep, and horses have?
Pig- only one pair; either embedded in thymus (young pigs) or adipose tissue (older pigs)
Cattle and sheep - two pairs; larger external is cranial to thyroid along common carotid. Smaller internal to thyroid
Horses- two pairs; larger (lower) parathyroid is in caudal cervical region and smaller (upper) is near thyroid gland
What breed has familial hypoparathyroidism?
Miniature schnauzers
What disease is associated with hypocalcemia and hyperphosphatemia?
Hypoparathyroidism (chief cell atrophy)
What causes primary hyperparathyroidism?
Parathyroid (chief cell) adenomas or carcinomas
Idiopathic
What causes secondary hyperparathyroidism?
Nutritional imbalances (excessive phosphorous, deficient calcium)
What sequelae result from secondary hyperparathyroidism?
Fibrous osteodystrophy
What is renal secondary hyperparathyoidism?
When renal disease is severe enough to decrease GFR and increase K+ levels
Increase in K+ causes decline in Ca++
Causes “rubber jaw”
Hypofunction of the pancreatic islet cells may result in what disease?
Diabetes mellitus
May be due to aplasia, necrosis, immune-mediated lymphoplasmacytic inflammation, chronic pancreatitis
Animals that have urinary tract infections, emphysematous cystitis, PU/PD, cataracts, hepatomegaly, glomerulopathy, retinopathy, and gangrene probably have what disease?
Diabetes mellitus
Histopathology of the pancreas of an animal with diabetes mellitus will have what two characteristics?
- Hydropic degeneration (vacuolar) or beta cells
2. Inflammation targeting islet cells
A small, yellow to red, sharply-delineated mass on the pancreas is probably what?
Beta cell adenoma
An animal that is neurologic from hypoglycemia probably has what disease?
Beta cell carcinoma
Multiple, small, grey to tan nodules on the pancreas is indicative of what disease?
Pancreatic nodular hyperplasia- incidental!
