With laminitis season upon us what better time to brush up on your knowledge of the potential causes, risk factors and management advice?

 

What is laminitis?

In the simplest sense, laminitis is damage to or failure of the laminae (which attach the pedal bone to the hoof wall) causing varying degrees of pain and lameness. This ‘failure’ of the laminae can result in rotation and/ or sinking of pedal bone which in the most severe cases, may lead to the pedal bone penetrating the sole of the hoof.

What causes laminitis?

The exact sequence of events or ‘mechanisms’ that  can lead to the development of laminitis remains elusive. Endocrine or ‘hormone’ related cases are now thought to be most common and include those associated with PPID (Cushing’s syndrome) and insulin dysregulation. These cases may be triggered by the horse or pony eating enough non-structural carbohydrate (NSC) from feed or forage to cause an increase in the amount of insulin circulating in the blood, although exactly how this causes laminitis is still not clear. In other horses and ponies, a disruption to the microflora in the large intestine or ‘hindgut’ as result of grazing ‘lush pasture’ or consuming feeds high in NSC may also lead to the development of laminitis. Less common causes include those related to toxemia as result of a retained placenta or severe infection such as pneumonia, and ‘mechanical laminitis’ or ‘supporting limb laminitis’ as a result of excess weight bearing due to infection or injury in the other leg.

 

Jargon Buster

-Water soluble carbohydrate (WSC) = simple sugars + fructan. Grass may contain up to 15% simple sugars (the main one being sucrose, the same sugar you put in your tea!) and 35% WSC! Fructan is the ‘storage form’ of sugar in grass and other plants/ forages.

-Non-structural carbohydrate = WSC + starch. Cereal based feeds are the largest source of starch in the horse’s diet. UK grazing, and therefore hay and haylage, contains very little starch.

 

Who is at risk?

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.

-Genetics e.g. native breeds or being a pony

-Recent weight gain & obesity, particularly in horses and ponies with a body condition score (BCS) of 7 or above

-Regional fat deposits including a cresty neck

-PPID (Cushing’s)

-A history of laminitis

-High intakes of non-structural carbohydrate (NSC) which includes starch, simple sugars and fructan, the ‘storage form’ of sugar in grass and other plants

-Insulin dysregulation

-Low adiponectin (measured via a blood test). Adiponectin is a hormone secreted by fat cells that helps to regulate glucose and fat metabolism

What is insulin dysregulation?

The term insulin dysregulation is used to describe any combination of

-Hyperinsulinemia – a high level of insulin in the blood

- An exaggerated insulin response after consuming starch and/ or sugar

- Insulin resistance – a failure of cells to respond to insulin

 

Feed & management tips

When it comes to nutrition, the main priories are to provide a low NSC diet and maintain a BCS of 4.5-5 out of 9.

 -Restrict or removing grazing: for horses and ponies at very high risk, complete removal from grazing may be the only option.

-Avoid turning out on sunny frosty mornings: cold temperatures combined with bright sunlight can cause high levels of WSC to accumulate in pasture.

-Avoid pastures that have not been properly managed. Mature ‘stemmy’ pastures and grass that has been stressed by drought or over-grazing may be deceptively high in WSC.

-Beware of binge eating: turning out for short periods without a muzzle or allowing free access to grazing after removing a muzzle may lead to gorging.

-Ideally feed a low WSC hay or low NSC hay replacer: soaking hay helps to reduce WSC but results are highly variable and can’t guarantee suitability for laminitics. Due to a loss of nutrients (and therefore dry matter) into the water, your haynet will also contain less ‘hay’ and more water post soaking. As a guide, increase the amount you soak by 20%.

 -Provide forage at a minimum of 1.5% bodyweight (dry matter) per day: in practice this equates to approximately 9kg of hay (11kg if you intend to soak it) for a 500kg horse without grazing. However unless your horse/ pony needs to lose weight, a suitable forage or forage replacer should ideally be fed ad lib.

-Balancers are ideal for good doers: balancers provide a concentrated source of vitamins, minerals and quality protein but due to the low feeding rate, contribute a negligible level of calories, starch and sugar to the total diet. If additional calories are needed, look for fibre based feeds that are low in starch and sugar and if necessary, high in oil (oil is high in calories but starch and sugar free).

 

Can you spot the signs?

Being able to spot the signs of an acute attack as early as possible maximises your horse/ pony’s chance of recovery. On the other hand, being able to identify signs of chronic laminitis will help you to adapt your management in order to help prevent future episodes. Check out our previous blog for more advice.

For more advice on managing your laminitic horse/ pony contact the SPILLERS Care-Line, 01908 226626.