Feeding the Laminitis-Prone, EMS, Cushings or Insulin Resistant Horse

This article is from the September 2020 Horse Deals magazine.

with Larissa Bilston, BAgrSc (Hons), Animal Nutritionist, Farmalogic

One of the biggest challenges in horse, pony and donkey ownership is ensuring a safe supply of forage and feed for a laminitis-prone equine.

Some horses with PPID and all horses with EMS are Insulin Resistant (IR) horses and are particularly at risk of developing laminitis in spring and autumn when pasture contains high levels of sugar
and starch.

Equine Metabolic Syndrome (EMS)

Horses with EMS commonly have an increased appetite and lose the hormonal regulations of satiety – the feeling of being full and having eaten enough. This means that they often need to have intake controlled by grazing muzzles and/or being locked
off pasture.

Forage for horses with EMS requires constant, detailed attention to sugar and starch levels. It is the spike in blood glucose and consequently insulin levels that triggers laminitis, so horses with
EMS can suffer laminitis without being overweight.

Obese horses with EMS should follow the dietary guidelines for weight loss.

Once a healthy body condition score is reached, EMS horses should be maintained on an intake of between 1.5 and 2% of bodyweight. If your insulin resistant horse loses weight on hay alone, increase their calorie intake with a hard feed of a low GI feed such as beet pulp, copra, legume hulls, lupins or oil. When using oils for weight gain, take care to keep the diet anti-inflammatory by providing enough omega-3 fatty acids to balance the added pro-inflammatory omega-6 oils.

Horses predisposed to EMS are usually ‘easy keepers’ so often do not need a hard feed, apart from a quality low dose mineral balancer powder or pellet, as they can remain a healthy weight from forage alone. Since they are often hay-reliant, EMS horses should also be supplemented with omega-3 fatty acids which have a general anti-inflammatory effect and aids insulin sensitivity. Exercise and some specific types of prebiotics also improve insulin sensitivity and glucose metabolism.

Choosing Safe Hay for EMS or Overweight Equines

Ideally, choose hay which has been analysed and has a combined ESC + starch value of less than 10%. Avoid high production grasses such as ryegrass, and do not feed cereal (oaten, wheaten) hay or chaff. If carbohydrate levels of hay are unknown, soak in warm water for 30 minutes or cold water for 60 minutes to remove soluble sugars. Drain and discard soak water before feeding. Soaking hay can reduce water-soluble carbohydrates by 30%.

Replanting Pasture for Horses

When planting horse friendly pastures in temperate zones, choose a mix of slower growing, higher fibre, lower nutrient varieties such as Cocksfoot, Browntop Bentgrass, Yorkshire Fog, Crested Dogtail Grass, Prairie Grass and Australian native grasses – Wallaby Grass, Native Wheatgrass, Native Bluegrass and Weeping Grass are amongst the best suited to grazing.

Species for horse-friendly pastures in tropical areas include Rhodes Grass (this is a high producing, low oxalate C4 grass) and native grasses such as Bluegrass, Native Wheatgrass, Mitchell Grass, Kangaroo and Wallaby Grass.

Safe Weight Loss for Obese Horses

Obese horses should avoid pastures with ryegrass and clover and usually need to be removed from pasture during spring and autumn, or anytime that pasture plants are stressed (e.g. after frost, waterlogging, etc).

It is important to restrict intake to 1.5% of bodyweight, which equates to around 7kg of hay for a 500kg horse or 3.5kg for a 250kg pony. Hay should be provided in slow-feeder hay nets or given in small meals every three to four hours to allow a healthy trickle-feed of forage into the digestive tract. Horses left for more than four hours at a time without anything to eat are prone to gastric ulceration and experience an increase in the stress hormones that signal the body to hold on to fat stores, which is the opposite of what is required.

Balance the diet with a quality vitamin and mineral supplement. These are available in low-serve, laminitis friendly pellets (look for a serve size under 300g) or add as a powder to damp lucerne chaff or 50–100g of damp beet pulp, copra or soy hulls.
Supplementing with specific prebiotics and omega-3 in the form of DHA (e.g. fish oil or algae meal) is also proven to improve insulin sensitivity which aids weight loss.

For horses locked off pasture and provided limited grazing hours, the safest times of day are the hour before dawn and two to three hours after dawn while daily plant carbohydrate levels are at their lowest. The safest pastures are rapidly growing, mid-length leafy grasses of native species or lower sugar introduced grasses. Avoid very short pastures and grass carrying seed heads.

Consider the use of hindgut buffers and probiotic live yeast to help maintain a more stable hindgut pH especially for horses with access to grazing.

Exercise Recommendations for Weight Loss

Effective weight loss programs include regular moderate exercise which burns calories and improves insulin sensitivity. Exercise recommendations for non-laminitic horses are low-to moderate-intensity exercise (canter to fast canter, ridden or unridden with heart rate 130 – 170 bpm) for more than 30 minutes at least 5 or 6 times a week.

In previously laminitic horses with recovered and stable hoof lamellae, minimum exercise recommendations are low-intensity exercise on a softsurface while carefully monitoring for signs of lameness. Work should be a trot to canter unridden with a heart rate of 110-150 bpm for at least 30 minutes, 3 or more times per week.

Choosing Safer Grass to Reduce Laminitis Risk

• Fast growing leaves are lower in sugars.

• Frost and drought cause plants to accumulate sugars.

• Shaded grass is lower in sugars.

• In sunlight plants make sugars. Overnight they use sugars to grow. Plants are safest to graze between 3am and 9am am if they are growing rapidly.

• Horses tend to over-eat fresh shoots after rain in spring and summer.

• The stalks and stems of mature plants are higher in sugars. Do not graze stems below 10cm.

• Stems, seed heads and grains are higher in sugars. Cut seed bearing stalks before grazing.

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