Laminitis is a painful condition involving inflammation of the tissues between the hoof wall and the foot (the laminae) that can affect horses, ponies and donkeys. It can occur at any time of the year and episodes may be linked to factors such as hormones and diet. Laminitis may cause permanent damage to the foot, and severe cases may involve rotation or dropping of the pedal bone, which can result in euthanasia. We discuss in-depth what laminitis is in horses below, by exploring causes, management, and prevention strategies.
What Is Laminitis In Horses?
Laminitis is when the sensitive laminae tissue in the hoof becomes inflamed. This tissue acts like glue, attaching the pedal bone to the hoof wall.
When this sensitive laminae becomes inflamed, the bonding between the bone and the hoof capsule weakens - not only is this inflammation painful, but it can lead to the pedal bone rotating and, in some cases, sinking through the sole of the foot.
What Causes Laminitis?
In the UK, laminitis is usually triggered by an underlying hormonal (endocrine) disease, such as Equine Cushings (Equine Pituitary Pars Intermedia Dysfunction) or Equine Metabolic Syndrome. Both of these conditions involve some degree of dysfunction (or resistance) of the hormone insulin, and it is this that likely plays an important part in the development of laminitis, although the mechanisms are not fully understood currently.
Laminitis can also be caused by inflammatory conditions such as colic, retained placenta in broodmares (Retained Foetal Membranes) and diarrhoea, as well as mechanical issues such as the overloading of one limb. Although these do occur from time to time, over 90% of laminitis is caused by hormonal diseases, so we will focus on these in this article.
Equine Cushings (Pituitary Pars Intermedia Dysfunction)
PPID is a disease that affects the pituitary gland, mostly in older horses. It primarily causes a change in hormone levels.
It is often associated with a range of clinical signs and secondary disease processes such as laminitis, a long and curly coat (hirsuitism), muscle wastage, lethargy, and abnormal fat deposits (especially at the crest and just above the eyes). Affected horses can also have a weaker immune system and be more prone to infections and parasitism (such as worms).
Dysregulation of insulin levels associated with PPID is likely to be a major trigger in developing laminitis in these cases.
EMS
Equine Metabolic Syndrome (EMS) is a disease of typically overweight horses and ponies (although not always). EMS causes insulin resistance, which acts similarly to Type 2 diabetes in humans. It is potentially the subsequent increase in insulin circulation that may trigger laminitis in these cases
In both PPID and EMS, there is a strong interplay between insulin, diet and the development of laminitis. Obesity is also closely linked with EMS and is an important risk factor for the development of laminitis. Not only that, but laminitis is often more severe in obese horses, as there is more weight and force through the foot.
Blood tests can be taken by your vet to help diagnose and treat both of these hormonal diseases, and this will be of utmost importance when it comes to the treatment of laminitis (as we will address later in the article).
Diet
As we have seen, laminitis is often triggered by a dysregulation of circulating insulin levels. These insulin levels are affected by levels of sugar within the diet, therefore excess sugar or starch can often trigger or exacerbate laminitis in horses and ponies. It is thought that this may be directly caused by an excess of insulin, called hyperinsulinaemia. For example, excess sugar due to the richness of grazing pasture is a common trigger of laminitis, as well as sugar or starch rich feeds.
Clinical Signs And Diagnosis Of Laminitis
Laminitis usually affects the front limbs, although the hindlimbs can still be affected. Most horses and ponies will share some of the following clinical signs of laminitis. However, the signs depend on the severity of the disease:
- A rocked back stance, putting weight onto hindlimbs and taking weight off forelimbs. This is known as the classic laminitis stance.
- Not wanting to walk, especially on harder (or stony) ground
- Refuses to pick up their hooves
- Constantly shifting weight between forelimbs
- Unwillingness to make a tight turn
- Lying down more often
- Excessive heat in the hoof wall
- Strong or bounding digital pulse at the back of the fetlock
- A stiffer gait and shorter stride
- Change in their temperament, behaviour, and energy
A vet can diagnose laminitis based on these clinical signs. However, they’ll also consider the horse’s history. Some studies suggest that 30% - 70% of horses experiencing laminitis go on to have a second bout of this disease.
The vet may wish to perform a blood test and x-ray images of the feet. This way, they can assess the severity of the disease and guide the treatment plan.
Management
In the short term, you and your vet may wish to do a range of things to make your horse more comfortable:
Give pain relief: Your vet will advise you on the possible painkillers. It’s typically an anti-inflammatory pain relief injection (such as bute or flunixin), followed by an oral course. Support the feet: You can achieve this by box rest on a deep bed of shavings. Sometimes, they need extra support, such as Styrofoam pads or specialist sole support. This helps shift and disperse the weight more through the sole onto the heels and the back of the foot. Adjust the feed ration: Look at the quality of hay and feed. You must monitor your horse’s overall calorie intake. Regularly measure and rate your horse’s weight. Rest: Your horse should be box-rested initially. Stop their workload until the tissues in the feet are more stable.
In the longer term, your vet may advise the following:
Investigation and treatment/management: Treat the root endocrine cause. For example, initiate medication for PPID and weight and diet control for EMS patients. Medication for EMS management may also be used. This can help regulate Insulin better and may reduce laminitis flare-ups. Remedial farriery: This involves reshaping the toe or fitting specialist shoes, such as heart bar shoes. This removes weight or excessive force from some foot regions, making the horse more comfortable. Diet and pasture management: Restrict access to fresh grass or calorific forage. Your horse might have to wear a grazing muzzle. Although the aim is to reduce the calorific intake of the laminitic pony, you should never starve them. A good fibre intake is essential for digestion and for preventing gastric ulcers.
Your vet may also recommend adding a low-calorie balancer at this stage, which is essential if your horse eats soaked hay or poorer-quality forage. Regular communication with your vet and nutritionist is essential here.
How To Prevent Laminitis
There are various methods you can implement when considering how to help prevent laminitis. Most of it has to do with your horse’s care or how you treat them:
Implement a low-calorie diet. Feed your horses little but often to promote digestive health. This way of eating is natural to horses in the wild, with their bodies adjusted to it. Restrict their grass access during the seasons with higher sugar content, like spring and summer. Regularly weigh your horse. Use body condition scoring and/or an electronic weight bridge to monitor your animal’s condition. Note down their food intake and weight regularly, to make sure they are getting an appropriate ration for their weight and condition Do daily checks of their feet. Check for heat in the hoof or an increased digital pulse. Always ensure they don’t suffer from mechanical issues, and never neglect foot care for more than eight weeks.
Prognosis
Laminitis in horses is often manageable, particularly if an episode has been identified and treated swiftly, with the root causes being addressed . It is a lifelong condition, so you must always account for it. However, once you implement a strict management plan, most horses and ponies live happy and pain-free lives.
Occasionally, some horses are refractory to treatment. If the frequency and severity of the flare-ups cannot be reduced despite intensive treatment and management and the horse’s welfare is compromised then euthanasia should be considered. After all, you don’t want your horse to suffer an impaired quality of life for a condition that isn’t improving.
If you suspect your horse or pony may be prone to laminitis or is experiencing signs of the disease then please seek veterinary advice.
Disclaimer:
This article is for information only, and should never replace any advice, diagnosis or treatment from your veterinary surgeon. Always contact your local vet or out of hours vet without delay if you have any concerns about your horse or pony.
