Equine Metabolic Syndrome

Question 1

What is EMS?

Answer 1

A collection of risk factors in horses leading to an increased risk of laminitis:

1. obesity - esp. regional adiposity
2. insulin dysregulation/resistance
3. dyslipidaemia or altered adipokine concentrations

Question 2

What is insulin resistance?

Answer 2

Decreased tissue response - fewer GLUT4 receptors translocated.

Question 3

EMS phenotype

Answer 3

~8-15yrs (middle-mature)
generally obese
regional adiposity - tail head, neck crest.

Overrepresented in pony breeds

Question 4

CSs EMS

Answer 4

overweight/obese/EMS phenotype
Acute or insidious onset laminitis/evidence of previous bouts
Brood mares - abnormal oestrus cycle, poor fertility

Question 5

Evidence of previous bouts of laminitis

Answer 5

Divergent growth rings, dropped sole, widened white line

Question 6

Dx EMS

Answer 6

NOT ONE SINGLE TEST PERFECT (also consider testing for concurrent PPID)

1. hyperinsulinaemia - single resting sample highly suggestive
2. measure resting glucose to detect the occasionally case of type 2 diabetes - hyperglycaemia
3. LOW high molecular weight adiponectin
4. dynamic testing - oral sugar test in-feed oral glucose test, combined glucose-insulin tolerance test (CGIT) and insulin tolerance test (ITT)

Question 7

Resting insulin test

Answer 7

High resting insulin = highly suggestive

Confounding factors - pain, stress, recent feeding (ensure no concentrates 4hrs prior)

Question 8

High molecular weight adiponectin

Answer 8

released from ‘healthy’ adipose tissue, down regulated by endocrinopathic adipose tissue. Values strongly correlate with insulin sensitivity
LOW values suggest insulin dysregulation
+ increased susceptibility to laminitis

Question 9

Dynamic testing

Answer 9

HIGHLY RECOMMENDED - many IR cases only detected by excessive endogenous insulin secretion in response to a glucose challenge and/or delayed return to normoglycemia.
oral sugar test in-feed oral glucose test, combined glucose-insulin tolerance test (CGIT) and insulin tolerance test (ITT)

Question 10

Problems with obesity

Answer 10

1. poor fitness
2. exacerbation of problems e.g. arthritis
3. EMS - increased laminitis risk

Question 11

Weightloss recommendations

Answer 11

Feed 1.5% ideal BW hay per day (or 1.2% current BW) + vit/mineral supplement or balancer.
DO NOT feed <1% target BW/day
Soak hay for 1-24hrs - reduce sugars and carbohydrates
Make gradual changes and ensure eating - risk of hyperlipaemia

Question 12

EMS management

Answer 12

1. weight loss
2. minimise increases in blood sugar - avoid cereals, grains, sweet feed.
3. restrict access to pasture - esp. avoid high light/low temp grazing
4. regular moderate exercise.

Question 13

EMS medical tx

Answer 13

1. Metformin - may increase insulin sensitivity
2. levothyroxine - thyroid hormone analogue - increases BMR & increases insulin sensitivity - encourages weight loss. TEMPORARY USE.