EVERY year the frosty and spring season brings with it threats of laminitis and while horse owners are told repeatedly that the horse population is getting fatter, it seems that the problem is still getting worse.

Nutrition advice lines are flooded with calls at this time of year on how to feed good doers and laminitics, but it is important to know what you are dealing with in order to treat your horse effectively. If you suspect that your horse may have laminitis, Cushing’s or EMS (Equine Metabolic Syndrome), you should consult a vet immediately.

“Laminitis is hard to define in the sense that the mechanisms involved in the development of the disease are not yet completely understood,” said Briony Mitchell, nutritionist at Allen & Page.

However, in the most basic sense laminitis is the structural failure of the lamellae (soft tissue) which attach the pedal bone to the inner hoof wall resulting in pain and lameness.

Unfortunately, the early developmental stages of laminitis occur without any signs, so once the horse shows foot pain the disease is already at an advanced stage. Despite symptoms being expressed in the feet, laminitis is actually a condition which affects the whole body and it is suggested that the condition results from a complex cascade of events commonly starting in the digestive tract.

Linked closely with laminitis and often confused with it is Cushing’s syndrome.

This is a common condition in older horses, although it can occur at any age. It is caused by an abnormality of the pituitary gland that results in excess production of certain hormones.

Horses with Cushing’s syndrome often suffer from glucose intolerance, causing them to become less sensitive to the action of insulin, and as such they cannot cope well with dietary sugar and starch. Horses affected by Cushing’s syndrome are at higher risk of laminitis all year round (not just during the summer) because of their hormone imbalances and glucose intolerance, and as such they must be monitored carefully.

Cushing’s cannot be cured but can be controlled with the assistance of drugs, similar to equine metabolic syndrome (EMS).

EMS is a state of hormonal and metabolic imbalance that the body gets when storing excessive body fat.

It is characterised by insulin resistance and the term ‘equine metabolic syndrome’ refers to those who are at more risk of developing laminitis as a result of underlying insulin resistance.

Although the area requires further research, one suggestion is that certain fat cells produce cortisol, (among other hormones) which interferes with the ability of insulin to move the glucose into cells.

Overweight animals having more fat cells means more cortisol is produced, causing greater interference with insulin. This could also explain why weight loss is effective in increasing insulin sensitivity.

This insulin resistance may be a contributory factor to their high risk of laminitis; however exactly how insulin resistance predisposes to laminitis is still largely unknown.

Owners who are ill-informed of the nature of the disease could be putting their horses at risk.

Owners should avoid turning horses out on stressed pasture or on frosty grass, particularly on a sunny morning when fructan levels in the grass will be high.

Providing high calorie forages such as haylage and allowing horses or ponies to become overweight, particularly if they are not exercised, are all common misconceptions surrounding laminitis.

Grazing muzzles are a great way to limit the intake of grass, as is fencing off a grazing strip or limited-sized paddock.