Endocrine System

Question 1

Describe the sequence of events when a horse is approached with a needle

Answer 1

Sees it
Hypothalamus releases CRH
CRH acts on pituitary to release ACTH
ACTH acts on adrenal cortex to release cortisol
Cortisol acts on pituitary and hypothalamus to stop releasing ACTH and CRH

Question 2

Disease in older horses that results in excessive release of ACTH

Answer 2

Cushings or Pituitary pars intermedia dysfunction (PPID)

Question 3

What happens when the pituitary releases excessive ACTH

Answer 3

ACTH stimulates adrenal gland to released cortisol into the bloodstream

Question 4

What are the clinical signs of excessive cortisol ** (8)

Answer 4

Hirsutism (long, curly hair that doesn’t shed)
Abnormal fat deposits
Hyperhidrosis (increased sweating)
Loss of muscle tone
Polyuria (excessive urination)
Polydipsia (excessive drinking)
Increased susceptibility to infections
Laminitis

Question 5

What type of horse is most likely to have cushings

Answer 5

Older, pony, mare

Question 6

How is cushings diagnosed

Answer 6

Clinical signs
Bloodwork
- ACTH levels
- Low dose dexamethasone suppression test

Question 7

How does a low dose dexamethasone suppression test (LDD) work

Answer 7

Measure cortisol levels
Give dexamethasone
Exogenous corticosteroid should suppress normal release of cortisol through negative feedback
Measure cortisol level again
- suppressed = normal
- not suppressed = cushings

Question 8

What is an adverse effect of LDD

Answer 8

Dexamethasone may predispose or worsen laminitis

Question 9

Alternative to LDD test

Answer 9

Measuring ACTH levels in blood stream, horse with cushings will have 6X higher than normal horse

Question 10

How is cushings treated

Answer 10

Supportive
- clipping hair
- dental care
- foot care
Medications (pergolide)

Question 11

How serious is cushings

Answer 11

Manageable
Severe laminitis = life threat

Question 12

Complications of cushings

Answer 12

Laminitis
Infections (skin and teeth)

Question 13

Disease that looks like cushings, may even be called ‘peripheral cushing’s syndrome’

Answer 13

Equine metabolic syndrome

Question 14

EMS is similar to what in people? What does a horse look like

Answer 14

Similar to type 3 diabetes
Fat deposits (crest), resistance to insulin and laminitic

Question 15

What is EMS

Answer 15

Obesity-associated insulin insensitivity

Question 16

What is happening in a horse with EMS

Answer 16

Tissues non-responsive to insulin, glucose intolerance develops
Pancreas continues to release insulin = high insulin levels circulating

Question 17

What type of horse will have EMS

Answer 17

8-18 years
Fat foundered ponies, no job, hard to feed different than rest of herd (Mouse?)
Cresty neck and fat deposits over rump/back
Geldings have fat deposits on sheath

Question 18

How is EMS diagnosed

Answer 18

Clinical signs, high insulin in blood

Question 19

How is EMS treated

Answer 19

Weight control, exercise, trace mineral supplementation (?)

Question 20

How serious is EMS

Answer 20

Frustrating, difficult to manage
Laminitis could be life threatening

Question 21

Complications of EMS

Answer 21

Laminitis

Question 22

Equine metabolic syndrome is sometimes called

Answer 22

Peripheral Cushing’s Syndrome