Laminitis - the facts
What is laminitis?Laminitis (also known as 'founder') is one of the most serious and painful conditions affecting horse's feet.
It can strike adult horses of all breeds at any time of the year and can be severely debilitating, resulting in excruciating pain, and in some cases it is necessary for euthanasia.
A simple definition of laminitis is inflammation of the laminae in the foot. Yet this is a vast oversimplification of a complex condition that involves an interrelated sequence of events that results in from the disruption of normal blood flow to the foot, causing swelling (inflammation) which may lead to weakening of the structures in the hoof and breakdown of the interdigitation of the laminae. In severe cases, the pedal (coffin) bone in the foot can rotate or sink downwards and may eventually come through the sole and be exposed.
Anatomy of the FootTo understand what occurs in the horse's foot it is important to have a knowledge of the structures within the foot, and how they contribute to a case of laminitis. The hoof capsule is made up of several parts, the horny wall, the coronet, the sole, and the frog. These encapsulate the bony skeleton consisting of the pedal bone, the navicular bone, and the lower part of the short pastern bone, and the associated surrounding soft tissues. Probably one of the most relevant soft tissue structures that contributes to cases of laminitis is the Deep Digital Flexor Tendon.
The Hoof horn and pedal bone are held in position by the interdigitating laminae. Layers of insensitive horn epidermal laminae project from the inner surface of the hoof wall and interdigitate with sensitive dermal laminae to form a functional connection between the hoof and the pedal bone.
The Deep Digital Flexor Tendon curves around the back of the navicular bone and attaches to the pedal bone generating a pull against the laminae that suspend the pedal bone from the hoof wall.
The blood supply to the foot plays an important role in cases of laminitis.
The network of arteries perforate the pedal bone and laminae dermis providing oxygen and nutrients to the tissues.
Impaired blood supply results in chronic hypoxia leading to ischemia, faulty keratinisation (producing laminitic rings seen on the hoof), and along with the constant pull of the deep Digital Flexor Tendon on the pedal bone can cause the separation of the interdigitating laminae causing the pain associated with laminits.
Laminitis can occur in two forms: acute and chronic. In acute cases, symptoms appear quickly and are severe; in chronic cases, the symptoms appear gradually over time and are usually relapses from previous acute episodes.
How can I recognise laminitis?Symptoms of acute laminitis include:
- Characteristic stance - weight is shifted to the hind limbs with the forelimbs stretched out in front to bear more weight on the heel of the foot and away from the toe.
- Reluctance to move and lameness, weight shifting when stood.
- Abnormal gait - 'heel before toe'.
- Hot feet with an increased digital pulse to the foot.
- Pain just in front of the point of the frog when pressure is applied.
Symptoms of chronic laminitis include:
- Rings in the hoof wall which are wider at the heel than at the toe.
- Bruising of the soles.
- Widening white line ('seedy toe'), possibly with recurrent abscesses.
- Dropped soles or flat feet.
- Laminitic ponies on lush grass often have a large neck crest which feels firmer in the early stages of the disease.
I thought only fat ponies got laminitis?Any horse can be affected by laminitis, but some horses are more susceptible than others. Factors which make a horse more at risk of developing laminitis are:
- Breed - ponies and heavy breeds.
- Obesity - overweight horses suffer from increased biomechanical strain on the laminae.
- Diet containing high carbohydrate content, eg grain.
- Abrupt changes in diet or overeating - especially consumption of excessive amounts of fresh grass or grain ('grain overload'), particularly in spring.
- Endotoxaemia - inflammatory GI conditions, severe colic.
- Endotoxaemia - Severe infection or illness causing high temperatures, eg retained placenta after foaling.
- Excessive weight bearing on one leg because of injury to another leg.
- Endocrine Conditions - Cushing's Disease (PPID) & Equine Metabolic Syndrome (insulin Resistance).
Equine Cushing's Disease (PPID) is one of the most common conditions affecting the endocrine system of both horses and ponies. The disease is caused by enlargement of the pituitary gland (hormone releasing organ) which is located at the base of the brain. The resulting effect is dysfunction of the pituitary gland, releasing uncontrolled increased levels of several hormones including ACTH (adrenocorticotropin hormone). ACTH travels through the bloodstream and acts on another hormone releasing organ, the adrenal gland, to increase production of cortisol, a type of steroid. High steroid levels have been shown to contribute to laminitis.
Equine Metabolic Syndrome (EMS) is a condition that often effects overweight horses (+/- large regional fat deposits), referring to insulin resistance and high circulating blood insulin levels, and recurrent laminitis. It is believed to share some similar attributes to that of human Type II diabetes.
Both Cushing's disease and EMS can be diagnosed with simple blood tests, performed by your vet, to allow treatment where necessary.
What can I do if I suspect my horse has laminitis?If you think that your horse has any signs of acute laminitis, call your vet as laminitis is considered a medical emergency. Your horse has a much better chance of recovery if treatment is started early.
While you are waiting for the vet to arrive you can make your horse more comfortable by:
- Bringing your horse in from the field into a stable.
- Providing a deep bed in the stable.
- Removing food (but do not remove water).
What will my vet do next?Your vet will carry out a clinical exam to diagnosis laminitis by:
- Asking about the recent health, diet and exercise of your horse.
- Examining your horse's feet and applying hoof testers to the frog.
- Apply a frog support to make your horse more comfortable.
- Taking x-rays (radiographs) of your horse's feet to look at the position of the pedal bone.
How is Laminitis treated?Treatment for your horse will depend on the severity of the symptoms seen. Any primary condition, such as a retained placenta, will be treated. Medical therapy may be given to reduce swelling and pain (anti-inflammatories), to fight infection (antibiotics), and to improve blood flow to the feet (anticoagulants and vasodilators).
Following x-rays therapeutic farriery can be carried out to trim the foot correctly and put on any required therapeutic shoes. Your vet will liaise with your farrier on the best option for your horse.
It is important to follow your vet's instructions carefully, and keep him/her informed on the progress of your horse.
Further preventative measures may be advised to help manage future bouts of laminitis. These may include advice on a weight loss plan diet, and routine foot care, including regular hoof trimming.
Will I be able to ride my horse again?Most horses treated for laminitis can be ridden again. However, this depends on the severity of the laminitis and the horse's response to treatment. It is important not to ride your horse until your vet has said that this is safe.
ConclusionIt is important take home to appreciate that laminitis is a multifactorial and complicated condition for which there is rarely a cure, and therefore management of the condition needs to be undertaken with careful consideration and dedication. Yet with careful management horses can return to a reasonable level of work. And taking the correct precautions can help prevent a horse from suffering from laminitis.
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