Horse Disease Focus - Laminitis
What is laminitis?
Laminitis is a painful inflammation of the soft tissue under a horse's hooves. This causes separation of the hoof from the foot and extreme lameness.
Laminitis is more common in ponies and draft horses, but can affect any breed or type of horse.
Laminitis causes pain in the feet and normally affects both front feet. It is thus sometimes missed in the early stages as bilateral lameness is harder to see and feel than unilateral lameness.
As the pain becomes worse, the horse will stand with both front feet pointed forward...this is the classic 'founder stance' which is always a symptom of laminitis. A horse with laminitis may also lie down more and in severe cases may refuse to stand. The digital pulse in the affected feet is increased and the hooves may feel hot. Hoof testers are commonly used to make a final diagnosis. The overall breathing and pulse rate may increase. X-rays may show rotation of the bones in the foot and a loosening of the hoof. Untreated laminitis can lead to hoof loss.
A horse that has had laminitis once is very prone to getting it again.
Laminitis is a potentially fatal condition. A horse that is suffering from laminitis should be placed in a stall with deep bedding so that it can lie down as much as it wants to, and which is large enough to keep it from getting cast.
The horse should not be forced to move during the acute stage. It should be provided plenty of fluids and in some cases IV fluids are administered. Bute or another NSAID is given for pain relief and to help reduce the inflammation.
Despite all of these measures, many horses that suffer from laminitis have long term hoof changes. Once the initial bout is over, the farrier should be involved in treatment as corrective shoeing goes a long way towards preventing recurrence and keeping a laminitic horse sound.
Treatment also involves treating the underlying condition that caused the laminitis. In some cases, long term reduction in work load or the amount of weight a horse is allowed to carry is indicated. As laminitis is primarily a disease of obesity, a horse that has had laminitis should be kept on a strict diet (in some cases this may mean no pasture for the rest of the horse's life - an apparently cruel measure that is much kinder to the horse than risking another bout of laminitis).
Most cases of laminitis are caused by an underlying condition, most often obesity. A small number of cases of mechanical laminitis or 'road founder' still occur. This condition was much more common when horses were used for transportation, and is caused by excessive trotting on hard surfaces. Preventing road founder is the primary reason why most tourist carriages remain at a walk. (Some companies also use mules, which are less prone to road founder than horses).
The primary cause of laminitis is obesity. Laminitis can also be caused by stress or by overeating - for example if a horse gets into the feed room. Ponies and draft breeds are more prone to laminitis than light horses.
The group of horses most prone to it are northern European pony and small horse breeds (such as the Fjord pony shown with this article). These horses have been bred and raised for centuries to endure poor provender and when put on lush grazing often put on weight dramatically. It is particularly important with ponies not to allow them to get obese. Restricting grazing, especially in the spring, is important. The use of a grazing muzzle can allow a horse to enjoy plenty of turnout while not being able to gorge itself. In England, horses are often grazed only at night, when grass is less nutritious.
Horses that have had laminitis before need to be kept on an even stricter diet. Grain should be fed only if absolutely necessary (horses kept in a group may need to be given a small handful of 'sympathy grain' when the others are fed). Any grazing at all may be contraindicated. Soaking hay significantly reduces its carbohydrate content and can be a key element in slimming down a fat pony. Treats should be eliminated or cut down significantly...this includes apples and carrots, which have a fair amount of sugar in them. Some companies sell low sugar horse treats.
Another risk factor for founder is when active horses and athletes experience an injury and are suddenly put on stall rest. Horses on stall rest do not need much grain and ideally should be fed none. If at all possible, they should be hand walked to give them at least some exercise, and they should be fed free choice, low protein hay.
Laminitis can also occur as a compensation lameness in the opposite foot to an injury that is taking a long time to heal - this is what happened to Barbaro, increasing awareness of laminitis amongst the general public (this can also cause laminitis in the hind feet, which is otherwise extremely well). Unfortunately, this is very hard to prevent...injuries can happen to the best kept horse and are by no means limited to racehorses. Any horse that has an injury causing it to put all its weight on one side should have that hoof carefully monitored to try and spot any problems early. (Compensation lameness can also take other forms, such as strain on tendons).