Lecture 21 4/29/25

Question 1

What is equine metabolic syndrome?

Answer 1

collection of metabolic and clinical features that include insulin dysregulation as a consistent component resulting in an increased risk of laminitis

Question 2

What are the three key hallmarks of EMS?

Answer 2

-insulin dysregulation
-obesity and/or regional adiposity
-high risk for laminitis

Question 3

What are the characteristics of EMS and PPID?

Answer 3

many of the features of EMS are shared with PPID, and horses can have both conditions concurrently

Question 4

What are the characteristics of insulin dysregulation?

Answer 4

-disturbance of the relationship between plasma or serum insulin and glucose
-any combination of fasting hyperinsulinemia, postprandial hyperinsulinemia, and peripheral or hepatic insulin resistance

Question 5

What can lead to hyperinsulinemia?

Answer 5

-excessive secretion from pancreatic B cells
-possibly decreased hepatic clearance

Question 6

What are possible pancreatic B cell stimulators?

Answer 6

-diets high in non-structural carbohydrates (NSCs)
-incretins like GIP and GLP-1

Question 7

What leads to insulin resistance?

Answer 7

inadequate response of insulin-sensitive tissue to insulin

Question 8

Which tissues are stimulated to uptake and store glucose by insulin?

Answer 8

-skeletal muscle
-adipose
-liver

Question 9

How does insulin act on cells?

Answer 9

by increasing the availability of GLUT on the cell surface

Question 10

What are the characteristics of active adipocytes?

Answer 10

-fat is metabolically and hormonally active
-produce resistin, leptin, and inflammatory cytokines
-local cortisol excess
-diet and genetic factors can activate them

Question 11

What is the cause of EMS?

Answer 11

interaction between genetics and environment

Question 12

What leads to insulin dysregulation in EMS?

Answer 12

-excessive calories to genetically susceptible horses
-development of obesity
-fat produces adipokines that can lead to insulin resistance
-vicious cycle in which cellular functions are negatively impacted

Question 13

Which breeds are predisposed to EMS?

Answer 13

-pony breeds/AMH
-iberic breeds
-gaited breeds
-morgans
-arabians
-warmbloods
-donkeys and mules

Question 14

What is the typical history for horses with EMS?

Answer 14

-“easy keepers”
-laminitis that may be chronic

Question 15

What are the risk factors for EMS?

Answer 15

*age
-risk increases with age
-yearly testing of at-risk horses > 5 years of age
*obesity
-exacerbating factor
*diet
-high NSC diets
*PPID
-link between EMS and PPID unclear

Question 16

What are the clinical signs of EMS?

Answer 16

-obesity and/or regional adiposity
-laminitis

Question 17

How can insulin dysregulation be documented?

Answer 17

-resting insulin concentration
-dynamic insulin testing

Question 18

What are the differentials for insulin dysregulation?

Answer 18

-PPID
-systemic dz
-pregnancy
-glucocorticoid administration

Question 19

What are the characteristics of resting insulin?

Answer 19

-practical
-no grain given within 4 hours of test
-hay and pasture are okay before test
-low sensitivity/high specificity; can give false neg. results
-can be used to assess if management is focused on controlling hyperinsulinemia

Question 20

What are the limitations of resting insulin?

Answer 20

-elevations occur with pain or stress
-may not be elevated in mild/early cases or chronic cases

Question 21

What are the options for dynamic insulin testing?

Answer 21

-oral sugar test
-insulin tolerance test

Question 22

What are the characteristics of the oral sugar test?

Answer 22

-preferred dynamic insulin test; gives more complete picture
-requires 3 to 6 hours of fasting
-relatively low within-horse repeatability

Question 23

What are the characteristics of the oral glucose challenge?

Answer 23

-one flake of hay given night before test
-baseline blood insulin +/- glucose measurement taken in morning
-corn or karo syrup administered and blood collected 60 and/or 90 minutes later
-want to measure insulin +/- glucose in post-sample

Question 24

What are the characteristics of the insulin tolerance test?

Answer 24

-hay and pasture allowed
-measure glucose at baseline and 30 minutes after administration of insulin
-less than 50% decrease in blood glucose indicates insulin resistance

Question 25

What are the characteristics of leptin?

Answer 25

-produced by adipocytes -tends to decrease appetite -elevated in horses with EMS due to obesity and leptin resistance

Question 26

What are the characteristics of adiponectin?

Answer 26

-adipokine that improves insulin sensitivity -has anti-inflammatory effects -tends to be decreased in EMS horses

Question 27

What substance is often increased in the blood of EMS horses besides insulin?

Answer 27

triglycerides

Question 28

What are the keys to EMS management?

Answer 28

-weight control through dietary management and exercise -control of laminitis

Question 29

What are the characteristics of exercise therapy in EMS horses?

Answer 29

-sound horses should be cantered/"fast" cantered -want to exercise sound horses for at least 30 minutes 5x a week while maintaining HR between 150 and 170 -previously laminitic but currently sound horses should be exercised unridden on a soft surface -previously laminitic but currently sound horses can do walking and brisk trotting 5x a week -any exercise is good unless laminitis is present

Question 30

What are the characteristics of dietary management in EMS horses?

Answer 30

-want diets low in NSCs with restricted calories -no grain or sweet feed -forages must be low in NSCs -avoid/limit pasture -provide a ration balancer to provide adequate vitamins and minerals

Question 31

How is weight loss achieved in EMS horses?

Answer 31

-foundation of diet should be hay -feed 1.5% of body weight in pounds -reassess every 30 days; can feed 1.2% of body weight in pounds if struggling to lose weight

Question 32

Why is it important to do a forage analysis?

Answer 32

low NSC content depends on hay type, growing conditions, stage of growth, drying conditions, and time of day

Question 33

What are the characteristics of soaking hay?

Answer 33

-possibly more effective with grass hay than alfalfa hay -must drain off water; contains the extracted NSCs -want to soak at least 60 minutes in cold water; longer soaks lead to greater NSC decreases -do not want to soak more than 12 hours; decreases other nutrients -steaming hay does not decrease NSCs as well

Question 34

What is Triple Crown Safe Starch?

Answer 34

a fortified commercial forage for horses that is low in NSCs

Question 35

What are the characteristics of straw as part of a low-NSC diet?

Answer 35

-want to use good quality straw -can make up as high as 50% of daily feed -want to introduce gradually and monitor for signs of colic

Question 36

When are low starch commercial feeds most appropriate?

Answer 36

-animals with appropriate BCS but insulin dysregulation -pregnant mares

Question 37

What is the best feeding regimen for glycemic control?

Answer 37

-small, frequent meals -hay before concentrates

Question 38

Why should pasture be eliminated or limited when trying to achieve weight loss?

Answer 38

the sugar content varies widely, especially when the grass is rapidly growing

Question 39

When are the carbohydrate levels lowest and highest in grass?

Answer 39

-generally lowest in evening -peaks at mid-day

Question 40

What are the characteristics of limiting pasture in EMS animals?

Answer 40

--limiting time may cause horses to eat faster -should consider checking insulin after 1 to 2 hours of grazing -can use grazing muzzles or maze/track systems to reduce grazing and weight gain

Question 41

What can be done if diet alone does not achieve weight loss in EMS horses?

Answer 41

*thyroid hormone supplementation -accelerates weight loss and improves insulin sensitivity in non-hypothyroid EMS patients -want to gradually reduce dose -only used as part of a complete management program *metformin -insulin sensitizing *chromium, magnesium, and/or cinnamon

Question 42

What are the characteristics of velagliflozen?

Answer 42

-SGLT-2 inhibitor -reduces reabsorption of glucose by kidneys so more is lost in urine -can lead to development of hypertriglyceridemia

Question 43

What are the indications for prescribing drugs for the treatment of insulin dysregulation?

Answer 43

-horses with hyperinsulinemia-associated laminitis (HAL) and severe insulin dysregulation not responding to other measures -first line management in horses with acute HAL to rapidly decrease insulin

Question 44

What is important about the use of drugs for management of insulin dysregulation?

Answer 44

-generally used for 3 months -want to monitor post-prandial insulins as well as hepatic enzymes and triglycerides

Question 45

What are other considerations for management of EMS?

Answer 45

-insulin tends to be higher in winter; want to avoid overfeeding or adding high NSC feeds -regular hoof care allows for monitoring for early signs of lameness