Description

Laminitis is one of the most serious, crippling diseases of horses, ponies and donkeys. Severe and recurring cases of laminitis can reduce a horse's usefulness or result in the horse being destroyed to prevent further suffering. Treatment requires patience and the expertise of a veterinarian who can accurately diagnose the disease and make recommendations for treatment based on the cause and the severity of the disease.

Laminitis begins when bacterial endotoxins and lactic acid are released into the horse's bloodstream. These endotoxins may be the result of carbohydrate overload from grain or fresh green pasture. They may also be a result of colic or infections in the intestines.

The endotoxins and lactic acid dilate the large arteries and cause constriction of the small capillary vessels that nourish the laminae - the soft tissue structures that attach the coffin or pedal bone of the foot to the hoof wall. Deprived of blood, the laminae swell, causing tissue damage because of the rigidity of the hoof wall.

The inflammation and damage to the laminae causes extreme pain and leads to instability of the coffin bone in the hoof. In more severe cases it can lead to complete separation of and rotation of the pedal bone within the hoof wall causing severe lameness.

The coffin bone may become detached from the wall, rotate, or sink, and often penetrates the sole. In acute laminitis, the horse is obviously lame and may refuse to stand or walk resulting in a medical emergency.

Symptoms

• Lameness, especially when horse is turning in circles
• Heat and increased digital pulse in feet
• Reluctant or hesitant gait
• "Sawhorse" stance
• Refusal to stand or walk
• Pain in toe region when hoof testers are applied
• Dropped soles
• Rings in hoof wall
• Bruised soles

Causes

Laminitis is often caused by conditions in another part of the horse's body. Digestive upsets due to grain overload, abrupt changes in the diet, or sudden access to excessive forage are feed-related causes.

Current research suggests that insulin resistance may be related to laminitis in several ways: fat tissues become overloaded and the stress releases inflammatory chemicals; there is a lack of insulin entering hoof cells depriving them of nourishment; decreased blood flow to the hoof starves hoof cells of adequate nutrition for normal functioning.

In addition, high fever or illness, severe colic, retained placenta after foaling, and prolonged doses of cortcosteroids are medical issues that are known to cause laminitis.

Horse owners are also warned about allowing horses to consume cold water when overheated because in some cases this can lead to laminitis. Excessive concussion to the feet, excessive weight bearing on one leg, and bedding that contains black walnut shavings have also been identified as causes of laminitis.

Prevention

Preventing laminitis is accomplished through proper horse management, with consistent practices in feeding, exercise and daily care routines, disease prevention, and good health care.

Avoiding feeding excesses, making sure the horse is kept at a reasonable weight, and limiting time in pastures during exceptionally lush growth will help prevent the development of laminitis. Horses should have unlimited access to fresh, clean water, except immediately after exercise when the amount and temperature should be regulated.

When making changes to routines and amount of exercise, horse owners are advised to go slowly and progressively. Avoid excessive concussion to feet and work-outs on rocky, hard, uneven terrain.

Illnesses, digestive upsets, and primary foot diseases should be addressed and treated immediately before complications can occur that might lead to secondary illnesses or conditions such as laminitis.

Treatment

Treatment of laminitis depends on the risk factors involved and the severity of the condition. Dietary restrictions to prevent overeating and too much weight gain are important. Administering drugs, such as antibiotics to fight infection, vasodilators to improve blood flow to the feet, anti-inflammatories, and painkillers may be recommended by the attending veterinarian.

Stabling the horse on soft ground, such as sand or shavings, encouraging the horse to lie down to relieve pressure on the feet, and corrective shoeing can be effective in both treating and preventing laminitis.

A certain amount of exercise on a daily basis to encourage blood flow into the affected area is also important. The healing process for laminitis is often long term, taking up to two years in severe cases. Regular examinations by a veterinarian can determine the extent of healing and help develop a timetable for return to full activity.