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Insulin Resistance and Equine Metabolic Syndrome - Coggle Diagram
Insulin Resistance and Equine Metabolic Syndrome
basics
defined as...
insulin dysregulation/resistance
tissues become less responsive
fewer insulin receptors
reduced intracellular signaling
pancreas responds to decreased response by secreting
more
insulin
persistent hyperinsulinemia
hyperinsulinemia with euglycemia
more insulin secreted to make up for reduced effectiveness
[glucose] is normal
hyperinsulinemia with hyperglycemia
severe cases
blood glucose can no longer be kept within the normal range despite elevated insulin levels
subclinical/clinical laminitis
obesity, regional adiposity
no evidence of concurrent
hypertension
atherosclerosis
cardiac disease
PPID and EMS exhibit some clinical overlap
predisposition to laminitis
will be difficult to control until primary dz ID'd
IR
hyperglycemia
why not both
pathophysiology
adipose tissue is physiologically and metabolically active
obesity is associated with....
up-regulation of systemic inflammatory responses
altered cellular metabolism and insulin regulation
genetics + obesity/adiposity + environment + diet
IR
increased risk of laminitis
hypothyroidism
obesity and laminitis commonly attributed to hypothyroidism in the past
no evidence to support hypothyroidism as a contributor to EMS
still helpful to manage thyroid hormone in some EMS horses
susceptibility
breeds and individuals with a geneic predisposition for metabolic efficiency
ponies
minis
Morgans
Saddlebreds
warmbloods
paso finos
overfed
high starch/sugar feeds
turnout on pasture
underexercised
obesity
Henneke BCS
1-9 score
7 or higher is obese
assess 6 points
neck
withers
back and rump
tail head
ribs
shoulder
may see regional adiposity rather than general
CS
acute or chronic laminitis
abnormal horizontal growth rings
radiographic evidence of P3 rotation/sinking
misshapened hooves
obesity or regional fat deposits
major differential PPID
diagnosis
confounding factors
if acute laminitis, delay testing until pain subsided
excitement (exercise, stress)
transient hyperinsulinemia
transient hyperglycemia
PPID
PE, BCS, regional adiposity
rads of feet
lab testing to demonstrate IR
rule out other common laminitis triggers
PPID
infectious diseaes
endotoxemia
testing for IR
baseline serum insulin and glucose, no grain fed > 4 hrs
insulin <20uU/mL is normal
20-50uU/mL is suspicious
do dynamic testing
over >50uU/mL consistent
dynamic testing
more sensitive
oral sugar test
fast 3-6hrs
administer corn syrup PO (68ml/1000lbs)
draw blood samples for serum insulin at 60 and/or 90min
results of insulin >45uU/mL is consistent with IR
insulin tolerance test
combined glucose-insulin test
management
diet
good news
equine food industry has fat horse products
bad news
many feed advertised as low carb are unsafe for IR horses
feed labels are not informative
supplements abound
low glycemic diet
avoid feeds containing significant sugar/starch
:forbidden: apples, carrots, candy
:forbidden: pasture grass
:forbidden: grain, sweet feed
sugar/starch should be restricted to < 10%
dry-lot and low-NSC hay
preferred
soak hay to reduce NSC
restrict calories
slow feeding strategies
grazing muzzle
mesh bagged hay
feed hay at ~1.5% of target BW/day + ration balancer
levothyroxine
accelerates weight loss and improves insulin sensitivity
use when
obesity is persistentdespite restrictions
laminitic
increases basal metabolic rate
48mg posid 3-6mo until target BCS is acheived, then taper for 4w
reverse obesity and insulin resistance
treat laminitis
avoid provoking insulin secretion
diet
exercise