Laminitis in Horses

Laminitis, also referred to as founder, is an inflammation of the laminae, folds of keratinized epidermal tissue that help to tether the internal structure of the foot to the hoof walls. The swelling in the tissues can cause the laminae to begin to disintegrate within the hoof itself, allowing the cannon bone to become separated from the hoof. This also gives the cannon bone the ability to rotate within the hoof, causing severe pain and in extreme cases, the coffin bone can penetrate the sole of the foot.

Laminitis is the inflammation of the laminae, the structure in the hoof that attaches the structure of the foot to the inside of the wall of the hoof.

This disorder has many symptoms. The feet of the affected horse are quite uncomfortable, and they will often walk with a slow, crouching gait with each foot being set down as quickly as possible. Changes in the shape of the hoof are often observed in horses with this disorder, with bands of irregular growth and the hoof itself becoming narrow and elongated. Other symptoms of equine laminitis can include: 

• Blood or pus from hoof
• Bruised soles
• Depression
• Exercise intolerance
• Feet tender to touch 
• Fever
• Heat from the hoof
• Increased pulse in feet
• Increased respiratory rate
• Loss of appetite
• Muscular trembling
• Reluctance to stand
• Shallow breathing 
• Shifting of weight
• Stiff gait
• Sweating

Types

All of the forms of laminitis should be considered emergency situations as even in acute and subacute stages the risk of the cannon bone turning within the hoof is high.

• Acute - Laminitis is in its acute phase during the first two or three days, and at this point the coffin bone is unmoved; many of the clinical signs are clearly apparent when the laminitis is acute
• Subacute - This refers to cases of laminitis that have extended to more than three days in length, but the coffin bone is still unmoved; generally, the symptoms are somewhat subdued during the subacute phase of laminitis
• Chronic - This is classically defined as any situation in which the coffin bone has been displaced

Laminitis can be instigated by several different conditions. Some of the instigators of foundering are as follows:

• Carbohydrate overload
• Corticosteroid use
• Cushing’s disease
• Hormone changes
• Ingestion of black walnut
• Metabolic distress due to overheating
• Physical trauma to the feet 
• Retained placental infection
• Too much lush grass (usually spring and fall)

It is crucial that you contact your veterinarian right away if you suspect laminitis as it can permanently affect your horse’s performance. The actions that are taken during the first 24 hours after the onset of the founder can be critical in protecting the capability of the foot or feet involved. Radiographs, also known as x-rays, are extremely useful in evaluating the amount of damage that has already occurred in the feet. 

Using this technique the examiner will be able to get vital information such as the angle of the cannon bone and the depth of the sole of the horse. Additional testing techniques, such as a venogram or nuclear scintigraphy, may be completed to assist in the evaluation of blood flow to the area of the feet. Standard blood tests, like a biochemical profile and complete blood count, will also be assessed to determine if there are any infections, imbalances, or toxins present in the blood.

Initial treatment of laminitis is focused on reducing the swelling and inflammation in order to prevent further deterioration of the laminae. Cryotherapy is frequently utilized to cool the hoof and to naturally reduce inflammation. In most cases, NSAID medications will also be used to reduce swelling and to manage pain. The horse’s shoes will most likely be removed, and specialized sole support or temporary therapeutic shoes will be applied to prevent further concussion and damage to the sole of the hoof.

It is generally not advised to reshoe the horse with metal horseshoes until at least three to four weeks have passed, and sometimes longer, depending on the farrier’s preference. If the horse’s cannon bone has been rotated, then special shoeing techniques, such as wedge pads and egg or heart bar shoes, may be employed to help rotate it back to its proper position. Infections are common with this disorder, and the hoof may need to be drained and the feet soaked in an appropriate disinfectant each day until they have healed completely.

Foundering is often triggered by an overload of carbohydrates, and once an equine has experienced laminitis, they are more prone to developing it again. One of the best ways to prevent that from happening is to change their diet in order to avoid the triggering from the overload of carbohydrates. The proper diet for a horse who has experienced foundering is a diet low in carbohydrates, calories, and grain that also includes high amounts of roughage. It is generally recommended that alfalfa hay and corn be removed from the horse's diet as they are high in sugar.