Equine metabolic syndrome Flashcards
Both EMS and PPID are characterised by
Both are characterised by hyperinsulinemia.
Both need management and medication for control.
PPID = pituitary pars intermedia dysfunction
main complication of both EMS and PPID
laminitis
Both are manageable, but incurable.
Differing features of EMS vs PPID. (5)
- EMS has breed predilection,
PPID doesn’t. - EMS can affect any age,
PPID affects older horses. - EMS is a metabolic disease,
PPID stems from central nervous system. - EMS horses often obese (but not always),
PPID horses often not. - EMS controlled mostly by management,
PPID mostly by medication.
Equine metabolic syndrome is
A clinical syndrome associated with an increased risk of laminitis that includes insulin dysregulation and any combination of increased generalized or regional adiposity, weight loss resistance, dyslipidemia, and altered adipokine concentrations.
EMS horses often obese, PPID horses often not. Affects any age but usually only certain breeds.
Main 3 risk factors of EMS:
- Insulin dysregulation/insulin resistance (ID/ IR)
- Generalized obesity (BCS >6/9)
- Local adipose tissue (“cresty neck”)
Also:
* Arterial hypertension
* Infertility
* Increased production of adipose tissue derived inflammatory cytokines.
* Higher level of circulating free fatty acids.
NB! EMS is usually associated with obesity, but not all EMS horses are obese.
Describe EMS Genetic predisposition.
Several breeds are at increased risk.
* Pony breeds are more insulin resistant compared to horses: estonian horse, finnhorse, Icelandic horse etc.
* But also: andalusian horses, arabian horses, warmbloods etc.
Most horses are between 5-15 y when first laminitis episode occurs.
Predisposition to gain weight and insulin reistance has been beneficial to survival in harsh conditions.
* Insulin resistance increases with age.
What increases insulin
sensitivity?
Exercise increases insulin
sensitivity.
Horses that are not in work are at higher risk of EMS.
Also, Chronic feeding of NonStructural Carbs-rich diet decreases insulin sensitivity.
Assessing obesity in horses.
Use Henneke body condition score.
* BCS 1-9
(Less suitable for ponies)
Use Cresty neck score (CNS 1-5).
* EMS if CNS >3
* “Crest enlarged and fat deposited more towards the middle of the neck”.
Also use, BCS - body condition scoring systems.
What would you use the Girth circumference to height ratio in horses for?
Assessment of body condition; if its fat or not.
Measure the heart girth and divide with height.
* Horses: ratio >1,26 means overweight
* Ponies: ratio >1,33 means overweight
What about the hooves can tell you a horse may be overconditioned (fat)?
Divergent growth rings on the hooves & a Stretched and hemorrhagic white line.
Normal fasted plasma insulin level in horses is
< 20 ug/ml. More likely to be <10 ug/ml.
Hyperinsulinemia is a known cause of laminitis especially if severe and prolonged.
Insulin level increased in:
* Pain (laminitis!)
* Stress
* Late pregnancy
* After eating a high Nonstructural carb meal
What is peripheral insulin resistance?
In horses with EMS, despite normal or elevated insulin levels, the body tissues fail to absorb glucose efficiently, leading to compensatory hyperinsulinemia as the body tries to maintain normal blood sugar.
This dysfunction is often linked to obesity or regional adiposity and contributes to a higher risk of laminitis.
EMS diagnosis
Must test resting plasma/ serum insulin level.
* Simple to perform: one sample needed
* Difficult to interpret as reference ranges are laboratory specific and many factors influence like time of the day, feeding, pain, stress…
Also question of Fasting.
* Even 6 hours can cause Insulin resistance.
* No fasting recommended any more.
* No grain feeding in previous 4-5 hours before sampling.
* Feed hay and sample a pain-free horse in the morning time.
Resting insulin level can be normal but the horse can have an abnormal insulin response to increased sugars in feed which indicates insulin dysregulation.
Dynamic testing is also an option.
EMS diagnosis: dynamic testing.
Principle: what is the glucose and insulin dynamic like when a certain amount of sugar is fed?
OGT – oral glucose test
* Horse is fasted around 6 hrs
* Glucose powder is given in a small amount of low-glycemic index feed.
* 1 gr/ kg of powdered dextrose + 1 ml/kg water + 1 gr/ kg low sugar chaff (husk).
* After 60 and 90 minutes: insulin and glucose are measured.
* Horse may not eat all of it so can also just mix with water and give via nasogastric tube.
OST – oral sugar test
* Test principle is same, but “Karo light corn syrup” is given orally at 0.15 ml/kg with syringe instead of glucose poweder.
* Gives less sugars at a time and is probably a more realistic amount.
* Available in USA – other corn syrups used elsewhere.
Take a baseline blood sample, and then another couple samples 1h later and 1.5h later.
EMS diagnosis: dynamic testing can also utilize the CGIT – combined intravenous glucose-insulin test. Explain it.
Horses are given regular insulin 0,1U/kg and glucose 150mg/kg.
* Glucose measured from blood 12 times in 2 hours.
* Or shortened protocol: glucose and insulin measured at 45 and 75 min.
If insulin sensitivity is normal, glucose returns to baseline level in 45 min.
Indication of insulin dysregulation if slower return to baseline and/or hyperinsulinemia.
- Stress before/during testing can give false positive results so place the IV the evening before and keep the horse in a quiet environment.
Be aware of potential hypoglycemia during testing (rare)
* Keep IV glucose solution on hand.
The 3 Ms for the tx of EMS.
management (feeing and exercise)
mechanics (farriery)
medication
Describe Weight loss programs for management of EMS.
Avoid feed high in NSCs (sugar, starch, fructose).
Start with hay 1,5% of BW (Weigh the hay)
* Should be with NSC content <10-12% (you need to have it analyzed).
If no effect, can decrease amount further and/or can replace up to 30% of hay with straw.
All changes must be gradual, too sudden reduction of calories increases the insulin resistance!
No pasture access at least for the time of the weight loss/maybe permanently. Most can have some pasture access if insulin dysregulation is under control.
* Modern grasslands are high in NSCs (to be avoided)
* Restricted access has no value: able to consume 1% of BW in 3 hours.
Some insulin resitance horses are not fat, can be in training and actively competing. How do you feed these ones?
- Energy has to come from non-soluble sugars.
- Concentrates that are low in Nonstructural carb content.
- Many commercial feeds available.
- Add oil to provide additional energy.
- Beet pulp is suitable.
How long should you rest an EMS horse after an episode of acute laminitis before starting a weight loss program with training.
Suggestion to keep horse in box at least 1 week for every day of active laminitis.
Exercise Increases insulin sensitivity even if no weight loss. Gradually increase duration, frequency and intensity.
Pharmacological options for tx of EMS when weight loss plan does not give expected results.
Aim: control plasma glucose level which then controls insulin level.
- SGLT2i (sodium-glucose co transporter 2-inhibitors)
- Ertugliflosin (Steglatro)
- Metformin HCl
- Levothyroxine
Drugs should be combined with feeding and training program, never used alone.
SGLT2i are?
sodium-glucose cotransporter 2 inhibitors for EMS tx.
- Promote urinary glucose excretion
- Plasma glucose level falls
- Pancreas secretes less insulin
Ertugliflosin (Steglatro)
an SGLT2 inhibitor not licensed in horses but has been tested.
- 0.05 mg/kg/day orally for 30 days
- 51 horses with laminitis, on an appropriate diet
- Reduction in laminitis score, plasma insulin levels and body fat.
- Treatment may need to be continued or started again because insulin level increases again.
Describe Metformin HCl for equine EMS.
- Human type 2 diabetes drug
- Reduces glucose absorption in the gut and synthesis in the liver
- Horses: oral bioavailability is poor
- 15-30mg/kg PO BID-TID
- 30-60 min before feeding
- Give for 25-30 days
Describe Levothyroxine for equine EMS.
- Increases the metabolic rate
- Decrase gradually: ½ dose for 2 weeks and then ¼ dose for 2 weeks
- 0,1-0,15mg/kg PO SID up to 6 months
Drugs should be combined with feeding and training program, never used alone.
