All about Laminitis in Horses

Spring is just around the corner and before we know it, the sun will be out and the grass growing like mad. This is the time of year when some owners’ thoughts turn to laminitis which is associated with the sweet grass of spring.

What is laminitis?

Laminitis is named after the laminae in the hoof. The laminae are layers of tissue with a rich blood supply which interleave together and support the structures within the horse’s hoof including the pedal bone. There are sensitive and insensitive laminae and the condition laminitis refers to the engorgement and inflammation of the sensitive laminae. This can be incredibly painful for the horse.

What causes laminitis?

There are three types of laminitis:-

1. Overload laminitis which is usually caused by excessive weight being placed on a specific limb, usually due to a problem elsewhere which causes the horse to load bear in this way. This is not a particularly common cause of laminitis but emphasises the importance of always supporting the opposing limb when the horse is lame
2. Inflammatory laminitis which comes from the starch overload associated with a grain rich diet or too much sweet spring grass. Partly digested matter builds up in the hind gut where rapid fermentation causes huge changes resulting in the absorption of toxins into the bloodstream. These make their way to the laminae in the hoof via the blood supply causing inflammation and severe pain
3. Metabolic laminitis is the laminitis associated with PPID or Cushing’s Disease and also Equine Metabolic Syndrome or EMS. In both of these diseases, horses do not have control of their carbohydrate metabolism and have abnormally high levels of insulin which can produce an incorrect and excessive response to starches, so that would include the carbohydrate element of grains and cereals and the sugars found in hay and grass. These diseases are distinct and separately identifiable even though a predisposition to laminitis is certainly common to both of them

The clinical signs of laminitis

The signs of laminitis can vary depending on how bad it is but would usually include some or all of the following:-

• Heat in one or both front feet
• A raised digital pulse which is consistent with inflammation in the laminae, this can sometimes be described as ‘bounding’ which means it is strong and throbbing; usually the digital pulse should be faint or absent
• A shortened stride worsening to a reluctance to walk at all
• An increased heart rate
• Unusual growth rings on the horse’s hooves
• What is described as ‘a typical laminitic stance where the horse or pony stands with their hind legs well underneath the body and leans backwards in order to relieve pressure at the toe on the front hooves

Treatment for laminitis

Depending on the cause, horses that are diagnosed with laminitis are usually put on immediate box rest. Cereals if fed should be removed from the diet and hay soaked to reduce the sugar levels. Appropriate anti inflammatory relief is offered, usually bute, and if necessary, intervention from the farrier to help support the feet. Blood tests may be relevant if the animal is aged in order to establish whether Cushing’s Disease is present, likewise if EMS is suspected then a blood test will confirm this. Box rest is essential as the foot is undergoing trauma and the horse needs to be restricted whilst the feet recover.

A horse with a mild case of laminitis will appear almost sound within a few days and many people make the mistake of turning the horse out too soon only for the whole cycle to start all over again. It is not uncommon for a horse to need box rest for six weeks before turn out recommences so that the trauma to the foot can completely recover. It is tempting not to adhere to this if the horse or pony appears sound but the feet need to be allowed enough time to return to a normal state.

How to prevent laminitis

• Know your horse. Horses often have heat in their feet as periodically the hoof receives a large influx of blood from the circulatory system and this, in the absence of a digital pulse, may be quite normal. Know what is normal for your horse. If it is a hot day then you would expect the hooves to be warm, on a cool or cold day any influx of blood and subsequent warmth in the foot should not last longer than a couple of hours. Check heat and digital pulse when you pick out your horse’s feet on a routine basis every day, that way you will quickly notice something out of the ordinary
• Be aware of how your horse moves so that you can spot a slightly shortened step or a minor reluctance to move forward and can act quickly
• Avoid grain diets in horses with a predisposition to laminitis so native ponies and good doers
• If your horse has been diagnosed with either EMS or Cushing’s Disease then treat as a potential laminitic and alter the diet accordingly. Avoid cereal based feeds, feed soaked hay as the sugars leech out into the water and restrict grazing in the spring and autumn
• Never turn out a stabled horse or pony on frosty grazing. The frost causes the grass to shut down which when it thaws, results in a surge of fructans which can cause laminitis in susceptible animals
• Monitor your horse’s weight as an obese horse is more likely to be insulin resistant. Years ago it was thought that it was the obesity which caused the laminitis simply on a dietary basis, vets now know that this is not the case but from the owner’s perspective, it boils down to the same thing – excess weight puts a predisposed horse at an increased risk of contracting laminitis

Although the horse has laminae in all four hooves, laminitis is usually seen most commonly in the front feet but in certain circumstances, it can occur in all four feet. The best way to deal with laminitis is to avoid it happening in the first place. Horses and ponies that have had a bout of laminitis are more likely to have it occur again and it can be an emotional and heartbreaking cycle to go through. Chronic or repeated laminitis does not usually have a happy outcome as the laminae can become so sufficiently weakened and damaged that they are no longer able to support the pedal bone which rotates and protrudes out through the bottom of the horse’s foot. There is no cure for laminitis only good management.