Laminitis Types, Causes and Treatment
Laminitis is a word we all dread to hear. While overweight animals are at greater risk of the condition the truth is that it can happen to any horse or pony at any time of year. It’s vitally important to be aware of the types, causes and signs of laminitis and respond as rapidly as possible by calling your vet who will be able to advise on the right treatment plan.
So what is laminitis?
Laminitis in the literal sense of the word describes inflammation of the laminae, which is the soft tissue within the hoof capsule connecting the pedal bone to the hoof wall. Once viewed as a distinct disease affecting the feet, laminitis is now thought of as a clinical sign of endocrinopathic disease, which includes conditions such as equine metabolic syndrome (EMS) and pituitary pars intermedia dysfunction (PPID).
What can trigger some types of laminitis?
The main trigger factor for laminitis in the UK is nutrition-related but unfortunately, because it is such a complex condition, we still don’t fully understand what causes one individual to get it but not another.
The most common cause of nutrition-related laminitis is an overload of rapidly fermentable carbohydrate either from starch found in cereals or sugars and fructan found in grass or forage.
Starch is a storage carbohydrate found in plants. Cereals such as barley and oats have high starch levels compared to forage; this is why the feeding of high levels of these cereals can trigger laminitis. If a large quantity of cereal is eaten in one go there may not be time for all of it to be digested in the small intestine.
When this happens, undigested cereal ends up in the large intestine where the method of digestion is fermentation by microbes (bacteria). Microbial fermentation of cereals causes an acidic environment in the large intestine. This in turn causes toxins to be released that can be absorbed from the gut into the bloodstream and transported around the body with detrimental effects.
Fructans are one of the main storage carbohydrates of UK grasses along with glucose, sucrose and fructose. Research has suggested that if fructans are not significantly broken down in the small intestine, they then pass to the large intestine and are fermented rapidly by microbes. This creates an acidic environment and leads to the release and absorption of toxins. This type of fructan overload is thought to cause the typical case of laminitis seen when a horse is turned out onto pasture.
If you are worried your horse or pony is showing signs of laminitis talk to your vet as soon as possible to obtain a diagnosis and devise a laminitis treatment plan which will include a special low sugar, high fibre diet [link].
More rarely laminitis can be caused by factors unrelated to nutrition. Overload laminitis is caused by the horse or pony putting too much pressure on a particular hoof, usually as a result weight transferal because of lameness in another leg. Other causes of non-nutritional laminitis include concussion of the feet, poor shoeing, retention of the placenta by the mare after birth and the administration of corticosteriod drugs in some cases.
Endocrine (hormonal) disease or endocrinopathic laminitis is now thought to be the predominant cause of lameness associated with laminitis. The hormone thought to be the most likely culprit is insulin. Insulin is a hormone that controls blood sugar, however with increased exposure to high non-structural carbohydrate (starch and sugar) diets with prolonged high insulin levels can lead to insulin dysregulation (abnormalities in insulin metabolism including high circulating blood insulin and insulin resistance). The exact mechanism of how high levels of insulin can result in laminitis hasn’t been clearly defined but it is the subject of much ongoing research.
The risk of insulin dysregulation is higher in certain breeds such as native ponies, cobs, warmbloods and cold-blooded horses such as Andalusians. However, the biggest risk factor, and one that is preventable, is obesity which is why it’s so important to always keep your horse or pony’s weight in check.
The signs of laminitis
Make sure you are familiar with the signs, types and causes of laminitis so that you can spot it early. Working fast with your vet to find the best management and treatment plan will give the best chance of recovery.
Signs of acute laminitis may include:
- Foot pain and lameness
- A typical laminitic stance (with the forelegs extended and the hind legs brought forwards
- Prolonged heat in the feet
- Excessive periods lying down
- Increased rate and strength of what is termed the “digital pulse” (this is felt where the digital artery runs over the back of the fetlock)
- Unwillingness to lift a hoof off the ground
- Shifting weight from side to side
- Painful response when pressure is applied to the sole of the foot
- General signs of pain, such as patchy sweating
Signs of chronic laminitis may include:
- Any of the signs displayed in an acute case of laminitis
- The hoof wall displaying characteristic laminitic rings
- Bruised soles (often with a flat or dropped appearance)