A definitive cause of laminitis and the exact mechanisms by which the hooves are damaged is still unknown, despite being the most researched aspect of lameness worldwide. Although laminitis occurs in the hooves, the underlying issue is often a disturbance elsewhere in the horse’s body. Laminitis is commonly associated with horses that have any condition (e.g. Cushing’s Disease and Equine Metabolic Syndrome) that leads to insulin resistance. The following situations are known to frequently precede an attack of laminitis:
- Excessive feed intake: The main cause of laminitis in horses in Australia and in most parts of the developed world is from allowing horses to overeat and become obese. Horses (especially ponies) allowed unrestricted access to pasture, particularly lush spring grass before the digestive system has had time to adapt are at extremely high risk. Pasture Laminitis commonly occurs in Autumn and Spring when there can be extremely high levels of sugar and starch in the pasture.
- Grain overload: Nutritionally induced laminitis through carbohydrate overload (grain, fruit, snacks, molasses) is another common cause. An excess of starch and sugars overflowing into the hindgut upset the microflora (bacteria), which in turn, produce lactic acid, increasing the acidity of the hindgut. A toxic environment is created and is released into the bloodstream via something called a leaky hindgut epithelium.
- Toxaemia: Horses that have high levels of toxins in the bloodstream are at high risk of laminitis. Bacterial, viral, plant, chemical and fungal toxins have all been implicated in causing laminitis. Watch horses that are suffering from fever, diarrhoea, colic (particularly after surgery), pneumonia, pleurisy and retained placenta. Treatment of the initiating cause must be accomplished before improvement in laminitis can be expected.
- Trauma: Excessive weight bearing on one leg due to injury, or fast or prolonged work on hard surfaces have been associated with a mechanical cause of laminitis.
- Steroids: Although controversial, prolonged use or high doses of corticosteroids may contribute to the development of laminitis in some horses.
- Other: Certain types of horses are prone to laminitis and particular attention should be paid to those that are easy keepers, have cresty necks, are obese or suffer from Equine Cushing’s Disease and Insulin Resistance.
As you can see there are many causes that could trigger an episode of laminitis. It is important that if laminitis is suspected that you seek veterinarian advice as soon as possible. In the next blog on laminitis, we will discuss “What to do if your horse has laminitis?”
Written by Shannon Godwin BAppSc GDTL