Understanding Laminitis

Understanding Laminitis

For a lot of equestrians spring and summer brings with it the joy of sunshine, warmth and long nights to enjoy longer rides and fun with our horses but for some it brings the worry of increased risk.

There are a multitude of factors that contribute to the condition in horses known as laminitis and if you are ever concerned you should always seek help from your equine vet and farrier. These individuals are highly trained individuals that have seen and assisted in dealing with many cases of this unpleasant condition.

Laminitis is a painful condition caused by damage or disruption to the laminae, which can lead to varying degrees of pain and lameness. The laminae are the sensitive tissues that connect the pedal bone to the hoof wall, helping to support and stabilise the hoof structure.

Most cases of laminitis are now grouped into three main categories:

  • Hyperinsulinemia-Associated Laminitis (HAL)
  • Inflammatory or toxemic laminitis, which can occur following conditions such as a retained placenta or severe infections like pneumonia
  • Mechanical laminitis (supporting limb laminitis), caused by excessive weight-bearing on one limb due to injury or infection in the opposite leg

HAL is now recognised as the most common form of laminitis. This category includes laminitis associated with Pituitary Pars Intermedia Dysfunction (PPID) and Equine Metabolic Syndrome (EMS).

The exact process, or mechanism, that leads to laminitis is still not fully understood. In cases of HAL, laminitis may be triggered when a horse or pony consumes enough non-structural carbohydrates (NSC)—commonly referred to as sugars and starches—from feed or forage to cause a significant or prolonged rise in blood insulin levels. However, precisely how elevated insulin causes laminitis remains unclear.

Laminitis is thought to affect approximately 3-5% of the equine population. Although any horse or pony can develop laminitis, a number of risk factors have been identified including:

  • High intakes of non-structural carbohydrate (NSC) or ‘starch and sugar’
  • Insulin dysregulation (ID) 
  • Genetics e.g., certain native breeds 
  • Pituitary Pars Intermedia Dysfunction (PPID) or ‘Cushing’s syndrome’, especially in the presence of ID
  • A history of laminitis
  • A recent change in grazing or move to ‘high quality grazing’ - regardless of the season!
  • Recent weight gain and obesity, particularly in horses and ponies with a body condition score (BCS) of 7 or above on the 1-9 scale (although lean horses and ponies can be at risk too)
  • A low concentration of adiponectin in the blood. Adiponectin is a hormone produced by fat cells thought to help improve insulin sensitivity

 

Spotting the signs

Being able to spot the signs of an episode early maximises your horse’s chance of recovery, so it pays to be vigilant, especially as subtle signs such as a slight reluctance to turn or shortening of stride can be easily missed. Signs of laminitis can include:

  • Weight shifting.

  • Changes in gait including a shorter stride or ‘pottery’ movement.

  • Reluctance to turn or cross the hindlimbs.

  • Reluctance to walk on hard, stoney or uneven ground.

  • Lameness.

  • Abnormal stance.

  • A strong/ pounding digital pulse.

  • Hot feet.

  • Signs of pain such as sweating and increased pulse, temperature and respiration rates (which may be mistaken for signs of colic).

  • Refusal to move or stand in severe cases.

Abnormal stance

We’ve all seen pictures of the classic laminitic stance but it’s important to remember that how the horse or pony stands will depend on the severity of laminitis and which feet are affected.  In fact, if all four feet are affected the horse or pony may stand normally.

Keeping your finger on the pulse

In a healthy horse/ foot the digital pulse may be faint or impossible to feel but it still pays to practice while your horse is sound and healthy. The digital arteries that run down the side of the leg and into the hoof ‘pulse’ with every heartbeat; the expression ‘pounding’ describes the strength of the pulse as opposed to the speed - it will feel like it’s ‘throbbing’. The digital pulse can be felt on the inside and outside of the leg from just above the fetlock (towards the back of the leg), over the fetlock and in the mid-upper pastern area. Remember to use your index and middle fingers and not your thumb, otherwise you may feel your own pulse. Apply gentle pressure – press too firmly and you may block the pulse.

Hot feet caution

Hot feet are not always the most reliable indicator of laminitis. Hoof temperature fluctuates and if your horse has been standing outside in the height of summer, hot feet are not necessarily a cause for concern.  However hot feet for prolonged periods or on a cold day and/ or heat in one or two feet only should raise suspicion.

Starch & sugar

Providing a diet low in non-structural carbohydrates (NSC) or ‘starch and sugar’ is one of the top priorities for managing those at risk of laminitis. However, the different terms used to describe starch and sugar can sometimes cause confusion. Here’s a quick guide to busting the jargon:

  • Non-structural carbohydrate (NSC) = starch + water soluble carbohydrate

  • Water soluble carbohydrate (WSC) consists mainly of simple sugars such as sucrose and fructan

  • Fructan is the ‘storage’ form of sugar in the majority of UK grasses and consequently hay and haylage

How much starch & sugar is ‘too much’?

Percentages are a useful starting point when it comes to comparing one feed against another, but they only tell part of the story. Ultimately, the amount of starch and sugar your horse will consume from any feed depends on how much of it they eat. For example:

  • 2kg of feed with a combined starch and sugar content of 9% contains 180g of starch and sugar.

  • 1kg of feed with a combined starch and sugar content of 18% also contains 180g of starch and sugar.

When it comes to choosing ‘bucket feed’ (as opposed to forage), consider the feeding rate and the amount of starch and sugar your horse will consume, rather than basing your choice on percentages alone. Restricting NSC intake to less than 0.5g per kilogram bodyweight per meal (<250g per meal for a 500kg horse) should be a suitable guide for most horses provided they are not severely insulin dysregulated.

Grazing

Did you know that a 250kg pony turned out to pasture 24/7 may consume enough energy (calories) to fuel a 500kg racehorse and almost 2kg of simple sugars from grass alone every day?!

 

Tips for managing grass intake

  • Restrict or remove grazing – horses and ponies at very high risk may need to be removed from grazing completely, especially at certain times of year such as during spring and autumn.

  • Beware of binge eating! Turning out for short periods may be counterproductive. Ponies can consume almost 1% of their bodyweight (dry matter) in only 3 hours. This may equate to two-thirds of the total daily forage allowance for those on a weight loss diet!

  • Consider using a grazing muzzle. Grazing muzzles have been shown to reduce grass intake by approximately 80% in ponies turned out for three hours, regardless of the season. However, some horses and ponies may simply eat more once their muzzle has been removed to compensate, so consider stabling or non-grass turn out for remainder of the day. Grazing muzzles should always be introduced gradually, be well fitted and should not be left on 24/7. 

  • If available, consider non-grass turnout for those at very high risk or at certain times of year. This can be a useful way of encouraging voluntary exercise and providing time for socialisation.

  • Try turning out at times and in places where WSC levels may be lower, for example overnight, early in the morning and in shady areas or on cloudy days.

  • Avoid turning out on pasture exposed to bright sunlight in conjunction with cold temperatures e.g., sunny frosty mornings.

  • Avoid turning out on recently cut hay stubble.

  • Where possible, avoid pastures with grasses likely to a have high WSC level content e.g., predominantly rye grass pastures.

I think my horse/ pony has laminitis; what should I do?

If you suspect your horse or pony has laminitis, stable them on a deep bed that goes all the way to the door and call the vet immediately. Box rest is essential for preventing further damage to the laminae and the vet will often prescribe pain relief. Initial diagnosis is often made based on clinical signs but in some cases X-rays, blood tests or other clinical tests may be needed to provide more information about the severity or potential cause of laminitis. 

 

Credit to Laminitis in Horses | Causes Signs Symptoms & Treatment - SPILLERS | SPILLERS Feeds