Endocrine Diseases, Pt. 2 Flashcards
Equine Metabolic Syndrome vs. Pituitary Pars Intermedia Dysfunction:
What 3 criteria are seen in equine metabolic syndrome? What 2 things contribute to these criteria?
- obesity and/or regional adiposity
- insulin dysregulation
- clinical or subclinical laminitis
genetics and environment (diet, pasture)
What are some higher genetic risk breeds associated with equine metabolic disorder?
“British-derived” ponies and “Andalusian/Spanish/Portuguese” breed
- ponies, miniatures
- Analusians
- Morgans
- Paso Fino
- Saddlebreds
- Warmbloods
What are the most common changes in BCS indicative of adiposity of EMS?
- generalized obesity
- cresty neck
- regional fat deposits
- absence of ribs
- creased topline
“easy keepers”
What kind of tissue is adipose tissue?
active endocrine organ that secretes adipokines and cytokines that contribute to adverse local and systemic effects —> more weight gain, laminitis
BCS and EMS:
What kinds of horses have naturally cresty necks?
STALLIONS - used to attract females
NOT SEEN IN MARES
What are the most common sites for regional adiposity associated with EMS?
- crest of neck
- withers
- behind shoulder
- over the ribs
- along the back
- tailhead
How is insulin affected by EMS? What 2 things does this result in?
hyperinsulinemia (resting and in response to carbohydrate challenge) - increased secretion or decreased clearance
- insulin resistance
- insulin dysregulation
What is insulin resistance? When is it considered compensated and uncompensated?
cells fail to respond to insulin
- COMPENSATED = hyperinsulinemia + decreased insulin sensitivity
- UNCOMPENSATED = hyperinsulinemia + hyperglycemia
How is insulin dysregulation diagnosed?
- fasting hyperinsulinemia
- postprandial hyperinsulinemia
- insulin resistance
What are 5 possible causes of hyperinsulinemia in EMS? What does this lead to?
- PPID
- obesity
- lack of exercise
- genetics
- high non-structural carbohydrates
laminitis (founder)
What is laminitis? What clinical signs are associated with laminitis in cases of EMS?
separation of the sensitive laminae that connect the horses hoof to the coffin bone (3rd phalanx), resulting in it rotating away and sinking into the sole of the hoof
- front feet situating in front of horse instead of straight underneath
- narrow-based stance when all hooves are affected
- increased digital pulse
- increased temperature of hoof
- recurrent abscesses
- hoof rings
What are the 3 forms of EMS?
- obese
- lean
- EMS + PPID
What clinical signs are associated with the 3 forms of EMS? What other signs are seen?
- OBESE - weight loss resistance, laminitis, cresty neck, SQ adipose deposits
- LEAN - laminitis
- EMS + PPID - laminitis +/- signs of EMS
DM, metabolic derangements, hyperlipemia, infertility, pedunculated lipomas, preputial/mammary gland edema
What endocrine tests are used for diagnosing EMS?
- RESTING insulin
- DYNAMIC post-prandial (OST) and tissue sensitivity (ITT) tests
When is resting insulin concentrations not able to be used to diagnose EMS?
winter exacerbation of insulin levels = no testing December-Februrary
How are resting insulin concentration levels performed?
- keep pasture/hay the same, but keep horse fasted from grain 4 hours before the test
- collect baseline blood in EDTA and serum separator tubes
- centrifuge in 4 hours
- separate plasma/serum
- plasma = insulin; serum = glucose
How is the oral sugar test performed?
- fast for 3-6 hours
- feed horse corn syrup
- collect blood at 60 and 90 minutes
- centrifuge samples within 4 hours of collection
- separate plasma/serum
- plasma = insulin; serum = glucose
How is the insulin tolerance test performed? What risk is associated? How is it avoided?
- horse does not need to be fasted
- collect baseline blood sample in serum separator
- administer 0.1 U/kg of insulin IV
- collect another sample of blood within 30 minutes
- centrifuge samples within 4 hours
- separate serum and measure glucose levels
hypoglycemia - feed meal immediately after last sample
Diagnosing EMS, endocrine testing:
What are some endocrine tests used to diagnose EMS?
- insulin baseline
- OST
- leptin baseline (increased internal adiposity)
- adiponectin (Europe)
- triglycerides
What aspects of the 3 criteria of EMS are managed for treatment?
- OBESITY/ADIPOSITY - BCS, weight
- INSULIN DYSREGULAYION - insulin status, leptin
- LAMINITIS - clinical, radiological
How is diet altered to manage EMS?
- STOP treats and grain
- hay intake should be 1.5% of BW and can be soaked
- put horse in a dry lot or allow in regular pasture in the morning or with a muzzle
What should be encouraged to help horses with EMS to lose weight?
evaluate foot health first, then encourage regular exercise an walking on pasture
What 3 medical treatments are available for EMS?
- Levothyroxine
- SGLT2 inhibitors - Velaglifozin, Canagliflozin, Ertugliflozin
- Metformin
When is Levothyroxine recommended to treat EMS? What is its purpose? How should dose be altered?
if EMS is resistant to management changes
induces mild hyperthyroidism to increase metabolism
reduce once weight loss is achieved and progressively wean off
What 3 side effects are noted with Levothyroxine?
- hyperexcitability
- increased appetite
- coprophagia
When are sodium-glucose cotransporter 2 (SGLT2) inhibitors recommended to treat EMS? What is its mechanism of action?
if there is laminitis and severe insulin dysregulation and owners are able to afford (expensive!)
inhibits glucose reuptake from glomerular filtrate = lost in urine
What SGLT2 inhibitors are available for EMS?
- Velagliflozin (not available commercially)
- Canagliflozin, Ertugliflozin (DM in humans, limited equine data)
When is metformin recommended to treat EMS? What does it do?
if there is poor owner compliance with diet
given 30 min prior to feeding or turnout (up to 3x daily) to decrease glucose absorption from the intestine
What are 5 other alternative treatments for EMS?
- omega fatty acids - flaxseed, fish oil, algae DHA (decreases inflammation)
- resveratrol
- cinammon
- chromium
- apple cider vinegar
(derived from human diet strategies to lose weight)
How does EMS compare to PPID?
EMS = all ages, diagnosed by insulin and glucose levels
PPID = comorbidity > 10 y/o, diagnosed by TRH stimulation and ACTH concentration
(insulin dysregulation is exacerbated by PPID)
