Understanding Equine Metabolic Disorders

Lydia F. Gray, DVM, MAMedical Director/Staff Veterinarian

Jessica NormandDirector of Supplement Marketing

June 8, 2011

Agenda1. What are the problems?2. A Review of Cushing’s Disease3. A Review of Equine Metabolic Syndrome (EMS)4. Questions

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What are the problems?

1. ObesityA 1998 USDA study estimated less than 5% of the US horse population to be overweight or obese while a paper published in 2008 by Virginia Tech showed this value to be closer to 51%.

2. Laminitis“Studies have shown that about half the adult horses that founder for no apparent reason have evidence of Cushing’s Disease.”

Dr. Dianne McFarlane, Asst. Professor, Oklahoma State University

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Equine Cushing’s DiseaseWhat is it?

A collection of clinical signs caused by chronic elevation of cortisol in the blood.

*Pituitary Pars Intermedia Dysfunction (PPID)

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Equine Cushing’s DiseaseWhat types of horses commonly get it?

• Between 18 - 23 years of age• Any breed• (Though common in ponies and Morgans)

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Equine Cushing’s DiseaseWhat does it look like?• Hirsutism and excessive sweating• Weight loss and muscle wasting OR• Weight gain and abnormal fat deposits• Lethargy and poor performance• Increased appetite• Increased drinking (and urination)• Delayed wound healing and increased infections• Chronic laminitis

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Equine Cushing’s Disease

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Equine Cushing’s Disease

What causes it?A enlarged and overactive pituitary gland normally

kept in check by inhibitory dopamine from the

hypothalamus.

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Equine Cushing’s DiseaseHow is it diagnosed?

• Physical appearance of the patient• Results of routine blood tests• Elimination of causes of similar findings• Low-dose dexamethasone suppression test• ACTH (stimulation) test• Combined dexamethasone suppression/thyrotropin-

releasing hormone stimulation test• (Domperidone) “Correlation of pituitary histomorphometry with

adrenocorticotrophic hormone response to domperidone administration in the diagnosis of equine pituitary pars intermedia dysfunction.”

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Equine Cushing’s DiseaseHow is it treated?

1. Good general health care2. Body clipping3. Improved nutrition

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Equine Cushing’s DiseaseHow is it treated?

4. Medicationa. Pergolideb. Cyproheptadinec. (Trilostane)

Efficacy of trilostane for the treatment of equine Cushing’ssyndrome. McGowan CM, Neiger R. Equine Vet J. 2003 June; 35(4):414-8.

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Equine Cushing’s DiseaseConsider Supplements

• Antioxidants: Vitamins E and C, Se, GSE• Immune Support: Adaptogens/other herbs• Weight Gain (if needed)

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Equine Metabolic SyndromeWhat is it?

A syndrome of obesity*, insulin resistance and laminitis in middle-aged horses.

*or regional adiposity

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Insulin: a hormone secreted by the pancreas that stimulates the uptake of glucose by tissues when sugar is abundant (after feeding)

Insulin Resistance: failure of tissues to respond appropriately to insulin

Equine Metabolic SyndromeDefinitions

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– a system for estimating fat cover over six different body areas to develop a single score for overall condition; ranges from 0 to 9

Body Condition Score (BCS):

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Cresty Neck Score (CNS) – a system for assessing fat accumulation in the crest, a particularly “risky” place for fat that may be associated with an increased risk of laminitis, ranges from 0 to 5

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Equine Metabolic SyndromeWhat types of horses commonly get it?

• Obese or with regional adiposity• Between 8 – 18 years of age• Specific breeds or types:

– Domesticated Spanish Mustangs– Pony breeds– Peruvian Pasos– Paso Finos– Tennessee Walking Horses– Rocky Mountain Horses– Saddlebreds– Morgans– Warmbloods

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Equine Metabolic Syndrome

What does it look like?• Obesity (7 – 9 body condition score)• Abnormal deposits of fat in the crest of the neck, behind

the shoulders, over the tailhead, above the eyes and in the sheaths of male horses

• Insidious onset of laminitis• (also, abnormally cycling or difficult to breed mares)

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Equine Metabolic SyndromeWhat causes it?

Although there is a strong genetic influence, obesity is the primary problem that sets off

the cascade of metabolic abnormalities

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Equine Metabolic SyndromeHow is it diagnosed?

• Physical appearance of the patient• Results of routine blood tests• Elimination of causes of similar findings• Fasting hyperinsulinemia• Glucose tolerance tests (CGIT, FSGIT)

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Equine Metabolic SyndromeHow is it treated?

Reverse the obesity!1. Increase exercise2. Provide strict diet3. Consider supplements4. Appropriate use of Thyro-L

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1. Increase ExerciseGuidelines:

• Under veterinary supervision if laminitic

• Start slowly• Turnout ≠ Exercise

Effect of short-term exercise training on insulin sensitivity in obese and lean mares. Powell DM, Reedy DR, Fitzgerald BP. Eq Vet J. 2002 Sept;34(S34):81-4.

Effects of exercise training on adiposity, insulin sensitivity, and plasma hormone and lipid concentrations in overweight or obese, insulin-resistant horses. Carter RA, McCutcheon LJ, et al. Am J Vet Res. 2010 Mar;71(3):314-21.

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2. Provide Strict DietGuidelines:

• Hay should be the basis• Feed 2.0% then 1.5% of current body weight daily• (Then feed 2.0% then 1.5% of ideal body weight daily)• Make sure NSC < 10%• Soak hay in warm water 30 minutes (cold 60 minutes)• Limit grass

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2. Provide Strict DietProducts that can help:

Grazing Muzzle

Small Hole Hay Net

Freedom Feeder

Withers & Withers IR Horse Treats Hilton Herballs (treats)

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2. Provide Strict Diet, cont.Guidelines:

• Do not feed grains, molasses, or other sources of sugar• Use vitamin/mineral supplement (“multi-vitamin”) or

ration balancer• Give sugar-free treats• Prevent scavenging!

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3. Consider SupplementsAntioxidants: Vitamins E and C, Se, GSEMinerals: Chromium, MagnesiumVitamins: BiotinAmino Acids: TaurineHerbs: Cinnamon, Fenugreek, BanabaDietary supplementation with scFOS improves insulin sensitivity in obese horsesPsyllium lowers blood glucose and insulin concentration in horses.

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4. Appropriate use of Thyro-L“Administration of L-T4 decreases blood lipid concentrations, improves insulin sensitivity and increases insulin disposal in horses.”

(it is not used as a treatment for hypothyroidism)

New drugs: Metformin, PioglitazoneEffects of the insulin-sensitizing drug pioglitazone and lipopolysaccharide administration on insulin sensitivity in horses. Suagee JK, Corl BA, et al. J Vet Intern Med. 2011 Mar;25(2):356-64.

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Summary

EMS Cushing’sWho? Middle-aged Seniors

What? Obesity, IR, Laminitis Pituitary dysfunction leads to increased cortisol; also immunosuppression (laminitis, IR)

Diagnosis “Drive-by” diagnosis (obesity or regional adiposity), bloodwork

“Drive-by” diagnosis (hirsutism), LDDST, ACTH

Medication No (Thyro-L short-term) Pergolide, cyproheptadine

Diet/Exercise Low sugar/starch Low sugar/starch

Supplements Antioxidants, IR Support Antioxidants/Immune,Weight Support (if needed)

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Questions?

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Questions?1. Is it okay to give glucosamine to a horse with IR or Cushing’s? Can I give my IR

horse a joint supplement?2. My horse is really sensitive to any grass and sugars it makes her feet really sore.

How does this happen?3. My horse has small feet & stands 15.3. I worry about his weight since he seems

to go from Lean & Mean to Fat & Ouchy overnight. I've taken him off alfalfa & put him on grass hay. His blood work is normal. What kind of diet should my performance horse be on?

4. I have a 15-year old Mustang that has foundered. She was severely overweight also. She has lost over 100 pounds, but is still crested. Can you suggest tests or supplements to her diet?

5. How can I help my geriatric pony reduce her excess fatty tissue build-up on her neck and buttocks area? She is slender otherwise and on a very restricted diet. I am afraid she starting to lose too much main body weight.

6. Did I cause my 9-yr old TWH to develop founder/insulin resistance by giving him too many SmartPak supplements i.e. 4 at one time? Are they sugar based for more palatability?

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Questions?7. My TWH gelding is hungry all the time. How do I keep his weight down and still

satisfy him? Is soaked, molasses-free beet pulp something I can feed him safely?8. Pergolide made my horse lose too much weight and still did not shed out. I

started him on Chaste tree berry and he shed out in one week. How can I safely put weight back on him and can he get turned out on pasture now? He foundered 4 times and is still being ridden.

9. My horses receive Thyro-L to assist with equine metabolic issues. Can this be managed just as effectively with a product like SmartControl IR?

10. My horse has Cushing's but has no signs of insulin resistance. Is it still important to limit the amount of sugars in his diet?

11. I am interested in mineral balancing to address imbalances in our hay.12. I have two Welsh Ponies who get sore feet if they are allowed on grass in the

spring/early summer. I have hesitated having them checked for metabolic disorder because my vet insists on doing a “dex” suppression test which I've read can be dangerous.

13. Side effects, if any, to worry about from long-term use of Pergolide. So far my pony has been on Pergolide for about 3 years & is doing great.

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Questions?14. I understand that omega fatty acids are important for Cushing's horses but they

all seem to be high in carbs. Can you address?15. Can metabolic disorders cause a mare who is barren for over 5 years to lactate?16. My horse Bandit takes thyroid medication through my vet. He is a very

aggressive eater, like he is starved to death. What can I do so he can enjoy some grass?

17. Can a horse have Cushing’s and Insulin resistance at the same time? How do you go about treating both at the same time? My mini is on Pergolide and a low starch diet. I exercise her everyday and she is beginning to lose a little weight.

18. If you have performed blood tests to confirm insulin resistance and they are normal but horse is showing some clinical signs, should you try treating with medication/supplements anyway?

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