What is Laminitis?
Laminitis is an extremely painful condition affecting 1 in 10 horses/ponies every year1 and can cause permanent damage to the hooves. Laminitis can affect any horse, pony, donkey or their hybrid at any time of the year and not just in spring – there is no ‘safe season’.
Laminitis affects tissue called sensitive laminae which are found in the horse’s hoof. The sensitive laminae act like Velcro to form a strong bond to hold the pedal bone in place within the hoof.
Laminitis causes the sensitive laminae to stretch, weaken and become damaged which can cause the pedal bone to move within the hoof (for example, think of a zip being un-done). In extreme cases the pedal bone can rotate and drop through the sole of the hoof which is excruciatingly painful. In such cases, euthanasia is likely to be the only treatment option to end the horse’s suffering. Laminitis can occur in any of the horse’s hooves but is more commonly seen in the front hooves.
Any horse or pony can be affected by laminitis, but certain circumstances can contribute to the likelihood of your horse developing the condition. Overweight horses or those that have previously suffered with laminitis are more susceptible. If your horse or pony falls into this category it is really important to ensure the correct management practices are in place to help prevent them developing laminitis.
Laminitis should be thought of as a sign of a disease rather than a disease itself. This means the cause needs to be investigated and then managed to help prevent future episodes. The causes of laminitis fall into three broad categories:
1) Hormonal Laminitis
There are two hormonal conditions that are known to be associated with laminitis:
Although it is currently unclear how these conditions actually cause laminitis, both diseases are associated with high levels of insulin in the bloodstream which is known to cause laminitis.
If your horse develops laminitis it is recommended that you test for Cushing’s Disease and assess body condition to determine whether EMS is present. Your vet will be best to advise on your specific circumstance.
As highlighted above overweight horses are much more susceptible to laminitis as obesity can also increase insulin levels in the horse’s blood. It is therefore really important to keep your horse at a healthy weight and monitor any changes.
Find out more about the dangers of obesity and how to assess whether your horse is a healthy weight.
2) Inflammatory Laminitis
If you feed concentrates as well as forage, this should be no more than is needed to provide the required energy for your horse and should be limited to 150-200 grams per 100 kilograms of body weight per meal2,3. To aid digestion it is advised to spread the daily concentrate ration over at least two meals a day. Speak to your vet or a nutritionist for further information on the specific dietary requirements for your horse.
Eating a large amount of concentrates in one go can cause an overload in the digestive system with undigested sugar and starch pushed through to the hindgut, where it starts to rapidly break down. This process can damage the gut leading to the absorption of toxins into the bloodstream. It is thought that the toxins may disrupt blood supply to the laminae and increase the risk of laminitis.
Other potential causes of inflammatory laminitis include some colic cases where the gut has been severely damaged, severe inflammation of the lungs and retained afterbirth (placenta) in mares after foaling.
3) Abnormal weight bearing Laminitis
Abnormal weight bearing laminitis can be caused when a horse has a condition or injury where it is unable to put weight on a leg so uses the opposite leg to support their weight. Laminitis can occur in the hoof taking the extra weight.
Mechanical causes of laminitis can include, too much length of toe, improper shoeing or foot trimming, fast or prolonged work on hard ground, fracture, joint infection, or soft tissue damage in the opposite limb4.
There is currently no conclusive evidence that corticosteroids cause laminitis in healthy adult horses without an underlying condition5. Your vet will be able to discuss the risks and decide on the best cause of action.
What’s different about donkeys?
Alex Thiemann, Senior Veterinary Surgeon from The Donkey Sanctuary, presents 'Donkeys and Laminitis'.
1) Pollard, D., Wylie, C.E., Newton, J.R., Verheyen, K.L.P. (2018) Incidence and clinical signs of owner-reported equine laminitis in a cohort of horses and ponies in Great Britain. Equine Veterinary Journal. 51(5), pp. 587-594
2) Julliand, V. De Fombelle, A & Varloud, M. (2006) Starch digestion in horses: The impact of feed processing. Livestock Science. 100(1) P. 44-52.
3) Vervuert,I et al (2009) Effect of feeding increasing quantities of starch on glycaemic and insulinaemic responses in healthy horses. The veterinary Journal. 182(1). P.67-72.
4) Evans. J. (2019) Laminitis – A year round problem. Available at: https://www.rossdales.com/assets/files/Laminitis_CHN_May19.pdf
5) Mcgowan, C, M. Cooper, D & Ireland, J (2016) No Evidence That Therapeutic Systemic Corticosteroid Administration is Associated With Laminitis in Adult Horses Without Underlying Endocrine or Severe Systemic Disease. Veterinary evidence. 1(1).
Wylie, C.E., Collins, S.N., Verheyen, K.L.P., Newton, J.R. (2013) Risk factors for equine laminitis: a case-control study conducted in veterinary-registered horses and ponies in Great Britain between 2009 and 2011. The Veterinary Journal. 198(1), pp.57-69.
Tadros, E.M., Fowlie, J.G., Marteniuk, J., Schott, H. C. (2019) Association between hyperinsulinaemia and laminitis severity at the time of pituitary pars intermedia dysfunction diagnosis. Equine Veterinary Journal. 51(1) pp52-56.