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’.
What’s different about donkeys?
Alex Thiemann, Senior Veterinary Surgeon from The Donkey Sanctuary, presents 'Donkeys and Laminitis'.
Laminitis affects structures called sensitive lamellae that are located inside the horse’s hoof. The sensitive lamellae act like Velcro to form a strong bond to hold the pedal bone in place within the hoof.
Laminitis causes the sensitive lamellae 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 even penetrate 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.
Causes of 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 (Endocrine) Laminitis
Hormonal laminitis is the most common form. It is now recognised that up to 90% of laminitis cases are caused by an underlying hormonal disease such as Equine Metabolic Syndrome (EMS) and/or Cushing’s Disease.
Cushing’s Disease is a long term, progressive condition caused by an imbalance in the hormones produced by the pituitary gland that can increase the risk of laminitis.
EMS is a group of signs that are usually associated with obesity and increases the risk of laminitis. The signs can include; abnormal distribution of fat, for example on the crest and hind quarters, resistance to weight loss and insulin dysregulation.
Although it is currently unclear how these conditions actually cause laminitis, we do know that both are associated with insulin dysregulation.
Insulin dysregulation is where the body has an abnormal response to starches and sugar when eaten. This can lead to insulin resistance where too much of the hormone insulin is released (hyperinsulinaemia). Hyperinsulinaemia is the direct cause of hormonal laminitis.
Weight gain more than doubles the risk of laminitis2 because it may cause hyperinsulinaemia. This demonstrates the importance of keeping your horse at a healthy weight and monitoring fluctuations.
Compared to Thoroughbreds; draught-types, cobs and native pony breeds (for example, Welsh, Connemara, New Forest, Shetlands & their crosses) are more likely to be obese which can increase the risk of laminitis. If you have a horse of this breed, you will need to be particularly vigilant in keeping your horse at a healthy weight with the correct diet and exercise to help decrease the risk of laminitis.
Find out more about the dangers of obesity and how to assess whether your horse is a healthy weight.
2) Inflammatory Laminitis
Inflammatory laminitis can be caused by eating a large amount of concentrates in one go; for example, a horse gaining access to the feed room and gorging on hard feed. The feed reaches the horse’s hind gut partly digested where it starts to rapidly breakdown (ferment). The rapid fermentation process causes huge changes within the gut which can result in gut damage, the development of severe diarrhoea (colitis) and the absorption of toxins into the bloodstream. Although it is still unclear, it is thought that the toxins may disrupt blood supply to the laminae and increase the risk of laminitis.
As well as colitis, other potential causes of inflammatory laminitis include some colic cases where the gut has been severely damaged, severe inflammation of the lungs (pleuropneumonia) 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.
Prolonged or fast work on hard ground may increase the risk of laminitis due to damaging the laminae.
There is little evidence that corticosteroids cause laminitis in healthy adult horses without an underlying condition. Your vet will be able to discuss the risks and decide on the best cause of action.
Signs of Laminitis
There are three general stages of laminitis:
Subclinical laminitis happens when microscopic changes within the hoof are beginning to take place, but the horse is yet to show, or is showing extremely subtle signs.
Acute laminitis is when it first develops, and the signs are associated with pain. Signs can be subtle which mean they may be mistaken for other issues such as general lameness, a foot abscess or stiffness. Knowing what is normal for your horse is important as any subtle signs of laminitis can be identified sooner. The earlier laminitis is noticed and vet advice and treatment provided, the less internal damage will be caused.
Here are some subtle signs of laminitis you can watch out for in your horse:
- Horse standing abnormally – the classic laminitic stance where the horse rocks back on their hind legs to take the weight off their front legs
- Lying down more than normal
A horse showing a classic laminitic stance. Photo credited to the Royal Veterinary College.
3) Chronic Laminitis
Chronic laminitis is usually where the horse has had repeat episodes of laminitis causing physical changes to the hooves or when the pedal bone has moved. Horses with chronic laminitis can be at a high risk of future episodes. Horses with chronic laminitis can still show signs of pain, but can also include:
- Changes to the shape and angle of the hoof
- Rings on the outer hoof wall
- Hoof wall cracks
- A groove/indent just above the coronet band
- Bruising on the sole of the foot, usually just in front of the frog
What Should I do if I Suspect my Horse has Laminitis?
Call your vet immediately for advice as laminitis should always be considered an emergency. Horses need to be treated as soon as possible to reduce their pain. Don’t force your horse to walk if they are resisting. Your horse is likely to be in a lot of pain and there is a risk of causing more damage to the laminae. Stay with the horse and wait for the vet to arrive.
Treatment and Management - Acute
Your vet is likely to prescribe medicine to control your horse’s pain and advise a period of box rest with a deep bed of shavings. Your horse’s hooves may be trimmed by your farrier to relieve any pressure and sole or frog supports fitted.
Investigating the cause is vital to prevent it from reoccurring. A blood test can be taken to check for an underlying hormonal disease. Depending on the cause, changes to the horse’s management, such as diet, may need to be made to reduce the risk of future attacks.
Treatment and management – Chronic
Your vet is likely to work closely with your farrier, as remedial farriery is a big part of the management of a chronic laminitic. The aim is to help relieve pressure, stabilise and maintain correct foot balance and rehabilitate the foot.
Options for pain management and alternative treatment options may be suggested by your vet.
In serious cases of laminitis (acute or chronic) where the prognosis is poor, euthanasia is often recommended to prevent further suffering.
Decreasing the risk of laminitis
Prevention is always better than cure especially as laminitis can cause extreme pain, lameness, permanent damage to the hooves and can increase the risk of future episodes.
- Regular exercise will help keep the horse at a healthy weight. For those horses that need to lose weight, a gradual fitness programme should be introduced. Exercise also has a positive effect on insulin regulation
- Monitor your horse’s weight closely using a weigh tape and getting hands-on by fat scoring
- The horse’s digestive system functions on fibre and the diet should be low in sugar and starch. A diet high in sugar is likely to encourage weight again and could cause hyperinsulinaemia and trigger laminitis in those susceptible (such as native pony breeds). The calorie intake of the horse should be monitored by weighing the amount forage you are feeding
- Current recommendations are to feed around 2% of the horse’s current bodyweight in forage per day (24 hours). If weight loss is required, it is likely that forage intake will need to be reduced lower than this. However, it is never advised to provide below 1.5% of the horse’s current bodyweight in forage per day without seeking vet advice. For example, a 500kg horse fed 1.5% of its bodyweight would be fed 7.5kg of forage per day
- Forage is likely to vary in nutrients, including sugar. You can send a sample of your forage to a feed company for nutritional analysis, especially looking at sugar content. The feed company should be able to discuss the results with you, but forage containing under 10-12% sugar/starch content is usually safer to use. Avoid feeding ryegrass hay/haylage as it can increase the risk of laminitis compared to other forage types, such as meadow or timothy
- If you’re unsure of the nutritional content of your hay then you can soak it before feeding to reduce sugar. The recommendations for how long you should soak hay for varies but it should be soaked for at least six hours in cold water or one hour in warm (16°C) water. Speak to your vet or a qualified equine nutritionist for advice if you aren’t sure what type of forage to feed or how long to soak your hay for
- Grass is a major contributor of calories in a horse’s diet. Grazing is likely to need to be restricted in overweight horses or those prone to laminitis
- Grazing can be restricted by using electric fencing to strip graze, setting up a track system or by using a grazing muzzle
- Don’t keep an overweight horse unnecessarily rugged through winter as this time of year can be used as an advantage to help the horse lose weight. Instead of un-used calories being laid down as excess fat, the horse can use the calories to keep warm. As spring approaches, an overweight horse is at a higher risk of laminitis
- Limit the amount of fast work undertaken on a hard surface
- Recent research3 has found the risk of laminitis increases if shoeing or trimming intervals are more than 8 weeks apart, highlighting the importance of keeping regular farrier appointments. Speak to your farrier for advice
- If you are concerned that your horse may have EMS or Cushing’s Disease contact your vet. Although Cushing’s Disease cannot be treated, medication is available to control the clinical signs
- Watch out for any subtle signs of laminitis – the earlier an attack is noticed, the greater the chance of aiding recovery
- Ensure that your feed room is securely locked to help prevent an escapee horse from gorging themselves on feed
- Avoid over-feeding with carbohydrate/starch feeds
- The horse’s digital pulse can be felt as blood flows into their hoof. Digital pulses should be either faint or absent in healthy horses but can be easily felt when they have laminitis. Monitor the horse’s digital pulses for any changes
- Consider re-seeding paddocks with a more suitable mix of grasses and herbs for horses which many companies now supply. Be aware that agricultural grassland may be predominantly clover and ryegrass which are high in sugar
- Call your vet immediately if you suspect a mare has retained her placenta after foaling, a horse with severe diarrhoea or is showing signs of colic
- If your horse has a non-weightbearing injury or condition, your vet may advise supportive bandages or boots to be fitted to help prevent laminitis in the supporting foot
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1) Pollard, D., et al 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) Wylie, C.E., et al 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.
3) Pollard, D., et al 2019. Identification of modifiable factors associated with owner-reported equine laminitis in Britain using a web-based cohort study approach. BMC veterinary research, 15(1), p.59.