What is laminitis?
Laminitis is an inflammatory condition of the laminae within the horse’s foot. Laminae form the attachment between the hoof wall and the pedal bone in the foot. They are inter-digitating structures that act like velcro holding the hoof wall to the internal structures of the foot. Inflammation of these structures is very painful. Severe cases can result in a loss of this attachment causing the pedal bone to move within the hoof capsule (rotation and sinking). Milder cases can subside with appropriate treatment, without any lasting structural damage.
Signs of laminitis
- The most common symptom is lameness, usually in multiple legs. This can range from a mild stiff, shuffling or slow gait, through to a complete reluctance to move at all or recumbency
- The lameness is usually more apparent on a hard or stony surfaces- horses are noticeably comfortable on soft ground.
- Reluctance to turn or difficulty with tight turns
- Reluctance to pick up feet or hold legs up for any length of time
- Shifting weight from foot to foot
- Heat in the feet and a strong bounding pulse to the foot (digital pulse)
- A leaning back stance with the hind feet more under the body
Causes of laminitis
There are multiple causes of laminitis, but research has shown that most cases are due to an underlying hormonal disorder – usually EMS (Equine metabolic syndrome) or PPID (pituitary pars intermedia dysfunction AKA cushing’s.)
EMS can occur in any horse or breed, but it is more common in native breeds. Chronic obesity can have effects on metabolism that causes insulin resistance, similar to type 2 diabetes in humans. When horses with insulin resistance consume rich grass or feed high in sugars and starch, they produce abnormally high levels of insulin in response. These high levels of insulin then cause inflammation in the laminae in the feet.
Horses and ponies with EMS can have cresty necks, abnormal fatty deposits on their body, or just be a ‘good doer’
PPID is a disease that can commonly affect older horses. It causes a spectrum of symptoms as a result of an over-production of various hormones, but one of the potential effects seen is insulin resistance, leading to laminitis in the same way it does with EMS.
Other less common causes of laminitis can include toxic causes in sick horses, limb overloading and excessive concussion.
Treatment of laminitis
- A visit from your vet is always advisable- the sooner the condition is correctly treated the better the longer-term prognosis
- Painkillers such as bute are often prescribed to make the horse more comfortable and reduce inflammation
- Box rest with a deep shavings bed is often recommended to minimise further damage and to make the horse more comfortable. Restricting movement is important to minimise the strain on the affected structures.
- Blood tests are often recommended to identify underlying disease such as EMS or PPID
- Dietary management – restricting access to high sugar/starch feeds. Often vets recommend a restricted amount of soaked hay as a lower sugar and starch diet.
- If your vet is concerned that there may have been structural damage within the foot e.g pedal bone rotation/sinking, they may advise radiographs to assess the degree of damage and guide further treatment and prognosis.
- Regular trimming and remedial farriery can be an important component of treatment. Radiographs can often aid your farrier in the support and careful correction of any damage that may have occurred.
- Occasionally, when symptoms are not responding to a dietary change, rest and anti-inflammatories, other medication may be recommended. Recently, a class of drug called SGLT2 inhibitors have started to be used to try to help reverse the insulin resistance and reduce the insulin spikes that drive laminitis in horses. These medications are not licensed in horses yet and are only prescribed for use under the medication cascade when clinical cases require them.
Prevention of laminitis
- Monitor weight regularly by body condition scoring or using a weigh tape and adjust feed intake accordingly
- Restrict grazing when grass is very rich and calorific
- Incorporate regular exercise into your horse’s life
- Consider testing at risk horses for PPID and EMS in advance of any laminitis developing
- Ensure feet are regularly trimmed to prevent long toes putting extra strain down through laminae.
- Avoid over rugging and feeding during the winter months to help with weight management