Lecture 21: Endocrine 3

Question 1

Where are the parathyroid glands located

Answer 1

2 pairs in the Cr. cervical neck region

lots of species variation

Question 2

What cells comprise the parathyroid glands and what do they do?

Answer 2

chief cells that secrete parathyroid hormone in response to low blood calcium

It acts on kidney and bone to increase blood calcium

Question 3

What are the 4 causes of hypoparathyroidism

Answer 3

lymphocytic parathyroiditis

primary or metastatic tumor destruction

parathyroid gland atrophy

iatrogenic (ex. accidental surgical removal)

Question 4

What are the clinical signs of hypoparathyroidism

Answer 4

hypocalcemia =
- weakness
-ataxia
-tremor
- tetany
- seizure
- restless

Question 5

What are the 3 types of hyperparathyroidism? What are the main causes?

Answer 5

primary (chief cell neoplasia)

secondary (renal or nutritional)

pseudohyperparathyroidism (hypercalcemia of malignancy)

Question 6

What species is most affected by hyperparathyroidism? What type of tumor is more common?

Answer 6

old dogs > old cats

adenoma > carcinoma

Question 7

What are the clinical signs of primary hyperparathyroidism

Answer 7

fibrous osteodystrophy
- increased resorptive bone lesions

hypercalcemia
- NS = weak/lethargy/tremble
- GI = anorexia/v/constipation
- urinary = PU/PD (disrupt ADH impact on kidney) + urolithiasis

Question 8

What are the gross changes associated with primary hyperparathyroidism? How does it influence the tx/supportive care?

Answer 8

one gland is larger (with tumor) and the others are atrophied

If you remove the tumor
- must supplement PTH and watch for hypocalcemia because the other glands are atrophied

Question 9

How does renal disease result in hyperparathyroidism?

Answer 9

increased PTH levels because there is low blood calcium
- low GFR = retain P = P+Ca bind = low blood Ca

impaired vit D production

mechanism = disease in a non-endocrine organ

Question 10

How does nutrition influence development of hyperparathyroidism

Answer 10

3 ways:
- low Ca
- Low vitD
- high P (most common)

all cause low Ca

Question 11

What is bran disease/big head disease? What species does it occur in?

Answer 11

secondary nutritional hyperparathyroidism due to excessive phosphorus in diet

horses

Question 12

What are the gross changes associated with secondary hyperparathyroidism

Answer 12

bilateral enlargement of all glands

Question 13

What are 2 common causes of pseudohyperparathyroidism

Answer 13

lymphoma
anal sac carcinoma

They make PTHrp (PTH analog)

Question 14

What are the gross changes of pseudohypoparathyroidism

Answer 14

all glands should be small/atrophied

associated C cell/thyroid hyperplasia

Question 15

What cells comprise the endocrine pancreas and what do they make?

Answer 15

islets of langerhaans
- beta cells = insulin
- alpha cells = glucagon

Question 16

What are the effects of insulin

Answer 16

increase blood glucose

muscle and liver and adipose uptake of glucose

anabolic metabolism

Question 17

What are the effects of glucagon

Answer 17

reduced blood glucose

increased energy release
- gluconeogenesis
- glycogenolysis
- lipolysis

Question 18

What are 4 risk factors for developing equine metabolic syndrome

Answer 18

• easy keeper (pony/donkey/spanish breeds/mustang)
• inactive
• high glycemic index diet (grass)
• obese with regional adipose (neck)

Question 19

What are the clinical signs of equine metabolic syndrome?

Answer 19

endocrinopathic laminitis

+/-PPID concurrant

Question 20

What are the 2 types of diabetes mellitus? What species are most affect

Answer 20

type 1/absolute def:
- dogs
- juvenile
- insulin dependent
- autoimmune destruction

type 2/relative def
- cats
- adults
- insulin independent
- impacted by lifestyle/obesity/genetics
- islet amyloidosis

Question 21

What are the gross lesions associated with diabetes mellitus?

Answer 21

few pancreatic lesions
- except if it was chronic pancreatitis

diagnosis when alive is best

Question 22

What are the extrapancreatic lesions and signs associated with diabetes mellitus

Answer 22

low body condition
dehydrated
secondary infection: emphysematous cystitis (specific to diabetes mellitus because high sugar urine ferments in bladder)

hepatic lipidosis

bilateral cataracts in dogs (not cats)

chronic renal or retinal disease

rarely
- gangrene
- peripheral neuropathy

Question 23

What is the most common islet cell hyperfunction and what species does it affect?

Answer 23

insulinomas

ferret (mainly)
- adenoma

dogs
- carcinoma

Question 24

What are the clinical signs of insulinoma

Answer 24

weak
ataxic
confusion
restless
seizure
coma
death

Question 25

What is the function of chemoreceptor organs?

Answer 25

sense O2/pH/CO2 in blood to regulate respiration and circulation

Question 26

What are examples of 2 chemoreceptor organs and where are they located?

Answer 26

base of heart = aortic body

bifurcation of common carotid = carotid body

Question 27

What is the main disorder of chemoreceptor organs

Answer 27

chemodectoma/paraglanglionoma

Question 28

What organ do chemodectomas usually affect?

Answer 28

aortic body > carotid body

Question 29

What animals are primarily affected by chemodectomas and why?

Answer 29

dogs
- bracheocephalics because they are always hypoxic and so the chemoreceptors are constantly being stimulated = increased risk of adenoma or carcinoma

Question 30

What is the main mechanism of chemodectoma damage?

Answer 30

non-functional but space occupying
- compress thin walled structures like atria and the right ventricle = can cause right sided CHF