Laminitis is a painful inflammatory condition of the tissues (laminae) that bond the hoof wall to the pedal bone in the horses hoof. It can affect any horse, of any age or sex, at any time of the year. Laminitis is caused by weakening of the supporting lamina within the hoof, leading to painful tearing of the support structure suspending the pedal bone within the hoof.
The level of pain a horse demonstrates does not necessarily indicate either laminitis or founder. Some horses show tremendous pain while they are laminitic, and others show very little.
There are many, many different causes of laminitis and it is a common misconception that laminitis is caused by over-eating grass only. We occasionally see laminitis in horses on box rest, or on very limited turnout. There are often a number of factors surrounding the onset and exacerbation of an episode of laminitis.
The type of grazing can be important. Nowadays, many ponies are liveried on land once used for cattle. This type of grazing may have been heavily fertilised and re-sown with particular species of grass which are not ideally suited to horses and ponies. Poor grass which is stressed by such things as an overnight frost or overgrazing will result in the formation of a type of sugar known as fructans in the grass, it is this type of sugar that can directly cause laminitis.
Occasionally, laminitis can develop in one limb where the opposite limb is painful for another reason. This is particularly a problem in heavy horses if they are affected by a foot abscess; the foot abscess causes the opposing limb to take more weight that it is accustomed to, resulting in laminitis.
Equine Cushing’s disease, also known as PPID, is a very common disease in equine animals from their mid-teens onwards, although it can be seen in animals as young as eight years old. The laminitis which develops secondary to PPID is very difficult to control unless the underlying disease is also treated. Owners with older horses and ponies should be extra careful about their animal’s weight and the horses may require testing for PPID, and develop a suitable nutritional strategy.
Equine metabolic syndrome (EMS), is another disease of overweight ponies and horses that leads to insulin resistance, and therefore an increased risk of laminitis. In cases of laminitis, we will often blood test for signs of EMS as well as Cushing’s disease.
Delays between foot trimming or shoeing are an important cause of stress and damage to the laminae. Regular visits by the farrier will also pick up the early warning signs of laminitis.
Laminitis usually affects both front feet but can occasionally affect one foot and occasionally hind feet. In most instances the affected animal will shift its weight from one limb to another, will be reluctant to move, may lie down and there is sometimes heat in the hooves with an increased ‘digital pulse’. A digital pulse can be difficult to find, but please ask your vets to show you how to find them next time they are with your horse. In milder cases, there may be only a slight change in the animal’s gait, moving in a ‘pottering’ fashion. These animals will go on to deteriorate further, unless they are rested and treated correctly.
It is absolutely essential that you contact your vet should your horse or pony show signs of laminitis. The treatment of this disease is time consuming and can be difficult, with a poor outcome in some cases, but if caught early enough and dealt with promptly and correctly it can be rectified.
There are a variety of medicines which can be used to help settle the pain, and reduce the ongoing damage. Box rest is extremely important and the box should be well bedded down, over the entire surface area of the stable. Over time, it is important that the affected animal loses weight in a controlled fashion.
Horses or ponies with laminitis should not be forced to walk or be exercised. Affected animals must not have their feet placed in cold baths, streams or ice unless under veterinary direction. Do not starve overweight horses in an attempt at inducing rapid weight loss.