This document summarizes equine endocrine disorders including equine metabolic syndrome (EMS) and equine Cushing's disease (equine pars pituitary intermedia dysfunction or PPID). EMS is characterized by insulin resistance, obesity, and laminitis. It commonly affects ponies, Morgans, and other breeds aged 10-20. Clinical signs include laminitis, reproductive issues, and regional fat deposits. Testing includes insulin/glucose ratios and oral sugar tests. Treatment focuses on weight loss through diet, exercise, and limiting carbohydrates. PPID is a pituitary gland dysfunction causing high cortisol levels. It mainly affects horses over 15 and clinical signs vary but include long hair coat, increased drinking,
2. Equine Metabolic Syndrome
Horses with:
insulin resistance
obesity and/or
regional adiposity
prior or current laminitis.
Are often “easy keepers.”
Typical age of onset is 10-20 years.
Pony breeds, Morgans, Paso Finos, and Norwegian
Fjords most common.
Arabians, Quarter Horses, Thoroughbreds,
Saddlebreds, Tennessee Walking Horses and
Warmbloods have also been diagnosed.
3. Equine Metabolic Syndrome
Clinical signs:
Laminitis – often begins in the
spring with rapid growth of
grass
Abnormal reproductive cycling
in obese mares
General obesity and/or regional
adiposity (fat deposits)
Cresty neck, fat deposits around
the tailhead, sheath and above
the eyes, with occasional
subcutaneous masses on the
trunk
4. Testing
Insulin/Glucose ratio
EMS horses are “insulin- resistant”, so insulin levels are elevated
Leptin
Oral Sugar Test:
feed Karo syrup, measure insulin and glucose
Combined Glucose-Insulin Test:
Give IV dextrose and insulin, measure glucose and insulin
5. Treatment
Weight loss
Restrictive diet
Dry lot or grazing muzzle
No access to rapidly growing/ spring* grass
No grain or specially formulated low calorie
supplement
Levothyroxine (Thyro-L, thyroid supplement)
*can happen any time of year!
6. Treatment Goals
Improve insulin sensitivity via:
Weight loss
Exercise
Reduction in carbohydrate (NSC) consumption
Continue to monitor weight carefully
Repeat insulin: glucose testing
7. Equine Pars Pituitary Intermedia
Dysfunction (PPID )
PPID or “Cushing’s syndrome”
A dysfunction of the pituitary gland resulting
in increased levels of cortisol.
Different disease process
than dogs or humans
8. Equine Cushing’s Disease
The age of onset is 7-42
years of age. Over 85% of
the horses are > than 15
years of age.
Ponies and Morgans have a
high incidence of the
disease but all breeds can
be affected.
9. Equine Cushing’s Disease
Clinical signs vary depending
on the stage of disease but
include:
Hirsutism- failure to shed a
long curly hair coat.
Increased drinking and
urination;
intake of water over 25-
30L/day; consistently wet
stall
Laminitis
Lethargy or docile attitude
Increased sweating
Ravenous appetite
10. Equine Cushing’s Disease
Clinical signs
(continued):
Muscle mass atrophy
(sway- backed or pot-
bellied appearance)
Regional adiposity
Recurrent infections:
sole abscesses, tooth
root infections,
sinusitis, and skin
disease
Infertility
Blindness
Seizures
11. Testing For Cushing’s
Dexamethasone supression test:
Injection of dexamethasone given, measure cortisol in 19 hours
Seasonal variation
ACTH
Single sample
Seasonal variation
TRH stimulation test
If screening tests are normal but Cushing’s still suspected
13. Supportive Care
Keep adequate body condition
Monitor clinical signs closely
Retest to assess drug dose, progression of
disease
Management of feet with appropriate farrier
care
14. Does this sound like your horse?
Early diagnosis and treatment is the best way to prevent
laminitis and other complications.
Call to get more information about testing and treating
your horse.
Spring is the best time to test!