Equine Laminitis
The Animal Health Trust is currently undertaking research into the important equine condition laminitis, following generous funding by World Horse Welfare (formerly known as the I.L.P.H.). The three-year funded research aims to:
- Estimate the frequencies of occurrence of laminitis in the general horse population of Great Britain.
- Identify and quantify risk factors for equine laminitis.
- Assess the efficacy of ‘metformin’ to provide clinical benefit for appropriate laminitis cases.
What is laminitis?
Laminitis is a highly painful and debilitating disease which occurs within the horse’s feet. The term ‘laminitis’ strictly means inflammation of the attachments between the hoof and the skeleton, but this is an over-simplification of the many events that occur within the foot when laminitis occurs. In severe cases there is sufficient structural failure that the hoof wall completely separates from the bone within the hoof leading to loss of suspension of the skeleton, and the development of severe pain and lameness.
What are the signs of laminitis?
The disease usually affects all 4 feet but the clinical signs are normally most obvious in the front feet. In the early stages of the disease (acute laminitis) the horse appears uncomfortable while standing and frequently lifts up alternate feet. As the disease progresses the horse develops a more obvious lameness, is reluctant to move and often adopts the classic ‘laminitis stance’ - the forelegs are placed in front of the body as the horse attempts to shift weight to its hindquarters and relieve pain in the front feet (Fig. 1). 
Closer examination of the foot often reveals: increased hoof wall temperature, swelling
the coronary band, pain when pressure is applied to the sole and increased pulses at the back of the pastern.
Figure 1. The classic stance of a horse affected with acute laminitis in the front feet (‘laminitis stance’). (Photo - Courtesy of Mr John Stewart MRCVS)
Horses with acute laminitis may recover or may progress to develop chronic laminitis which is characterised by failure of the hoof wall to suspend the skeleton. Displacement of the bones of the skeleton within the hoof capsule alters the appearance of the external hoof wall over time (Fig. 2). Chronic laminitic cases are susceptible to recurrent bouts of painful, acute laminitis in the future.
Some ponies with laminitis show no obvious signs of lameness (acute laminitis) but do show changes to the hoof consistent with chronic laminitis.
Figure 2. The appearance of unequal, divergent (widest gap at the heels) growth rings on the hoof wall. Other chronic laminitic changes to the hoof include: altered foot shape, changes in the hoof angle, bruising of the sole, widening of the white line and a palpable depression of the coronary band. (Photo - Courtesy of Mr John Stewart MRCVS)
What causes laminitis?
There are many causes of laminitis however the most frequent cause in the United Kingdom is believed to be the excessive ingestion of lush grass, particularly likely to happen in the spring time. Other common causes include ‘gorging on grain’, over-exercising on hard-ground, excessive weight bearing following injury to another limb and some systemic medical conditions – such as retained placenta following foaling. Laminitis is commonly associated with ‘Cushing’s Syndrome’, a condition affecting older ponies who classically develop a long, curly coat. Laminitis has also recently been linked to a condition termed ‘Equine Metabolic Syndrome’, which is a predisposition for over-weight ponies to develop the disease.
What to do if your horse shows signs of laminitis
Acute laminitis is a medical emergency and requires immediate veterinary attention. If you suspect laminitis it is important not to move your horse unnecessarily as forced exercise will increase the amount of damage within the hoof. Cases of suspected laminitis should be restricted to a deep-bedded box, with access to hay and water awaiting veterinary attention. Chronic laminitis cases also require regular attention from both the vet and farrier. Your vet will be able to advise you on the appropriate medical treatments, management changes and therapeutic shoeing approaches dependant on the individual case.
What is the prognosis if my horse has laminitis?
It is important for horses to receive prompt veterinary attention in the early stages of laminitis. Complete recovery from acute laminitis is possible and horses can regain full athletic function within a few months. However, once the chronic stage of laminitis (physical changes to the hoof wall reflecting the breakdown of the hoof-skeleton attachments) has been entered the prognosis for return to athletic function is poorer. Treatment of acute laminitis is therefore crucial to prevent the horse developing chronic laminitis.
In severe laminitic cases humane destruction (euthanasia) is indicated on welfare grounds as the only means to relieve the unrelenting pain and suffering associated with the disease.
Prevention of laminitis is preferable to treatment as not all horses respond well to therapy. Preventive measures to minimise the risk of laminitis include: restriction of access to lush pastures and grain, prevention of obesity, care not to over-exercise on hard ground and prompt treatment of systemic medical conditions which can lead to laminitis.
If you suspect your horse has laminitis please contact your own veterinary surgeon
Links:
World Horse Welfare (formerly known as The International League for the Protection of Horses) works to protect horses from abuse and alleviate their suffering by rehabilitating, campaigning and educating world wide. For more information on World Horse Welfare please go to www.worldhorsewelfare.org
The Royal Veterinary College (RVC), London is the United Kingdom's largest, oldest and only independent veterinary school. Since its foundation in 1791, the Royal Veterinary College has become a world-leader in veterinary and biomedical teaching and research. For more information on the RVC please visit www.rvc.ac.uk