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,

1. Equine Endocrine Disorders
Clare Ryan, DVM, PhD, DACVIM
Badger Veterinary Hospital
Client Education Seminar
February 7, 2013

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

12. Treatment for Cushing’s
 There is no cure
 Pergolide (Prascend®)
 Cyproheptadine

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!

15. Questions?