With laminitis reportedly affecting 1 in 10 horses in Britain these days, it’s important to make sure you understand what can cause the condition and recognise the signs.
Laminitis in horses occurs when the laminae starts to break down, causing the pedal bone to pull away from the horse’s hoof. The laminae is a soft tissue structure that holds the horse’s pedal bone to the hoof. It has a high blood supply and a very high nerve content.
Although laminitis is considered a disease, it can also be indicative of other health issues elsewhere within the horse and could be symptomatic of a compromised immune system, a digestive imbalance or even a hormonal imbalance.
Regardless of the cause, laminitis is a serious and very painful condition that can affect any type of horse, pony or donkey any time of the year, and not just the fat native pony.
However, although laminitis in horses is becoming more common, it is estimated that 80% of cases could be prevented with correct management.
Common Causes of Laminitis
Overeating and Obesity
Overeating on foods rich in carbohydrate or rapidly fermentable fibre (cereals, coarse mixes, rapidly growing or fertilised grass) can be the easiest way to trigger laminitis in horses.
Obesity is still considered the most common cause of laminitis and as an owner you should always aim to keep your horse or pony at no greater than condition score 3. This means they should not have a fat deposit along their crest or at the tail head, around the sheath or udders or over the loins. You should be able to feel their ribs easily by running your hand along their side. In fit or finer horses, you could also just be able to make out the outline on the last couple of ribs.
If it is established that your horse or pony is overweight, one of the first things you can address is the amount of rich food and grazing that is available. Where possible, limiting the grass intake by using a suitable grazing muzzle or providing limit access to grazing is an important place to start, ideally, in a paddock that hasn’t been fertilised. The use of a muzzle will restrict the amount of grass the horse can consume per hour, but will still allow them to graze and consume forage which is vital to the health of the horse.
Where it is not possible to use a muzzle, you may want to consider stabling or arena turnout (or turnout in a bare field). You will have to provide an alternative form of ample forage for your horse or risk other health issues arising (such as colic or ulcers). This could be second cut hay, high fibre haylage, or hay replacement chaff. Whichever you choose, it is vital to ensure enough is provided throughout the day and at intervals to ensure the horse never goes longer than 3-4 hours without access.
As a guide, this is the absolute minimum amount of forage per 100kg of body weight your horse should be getting for each of the different forage options:
Hay - 1.22kg
Haylage - 2.5kg
Chaff - 1.18kg
Even overweight horses still need their essential vitamins and minerals, every day. Try to avoid compound feeds with high feeding rates. Even if the sugar & starch levels are low, by the time the recommended daily amount has been fed, a lot of unrequired sugar & starch has been ingested.
Instead look at feed balancers. A good feed balancer will provide the horses essential vitamins and minerals in around 100gms of balancer per 100kg of bodyweight. (500gms of balancer vs 3kg of high fibre cubes).
Once the diet has been addressed, have a look at your horse’s exercise regime. If there is no present signs of laminitis and the horse is capable, exercise will always be the best way to reduce excessive weight. It doesn’t have to be ridden work, even a 30-minute lunge session, anywhere that is safe and suitable, will contribute greatly to reducing that waistline.
- Drug Induced Laminitis
Giving corticosteroid drugs to susceptible or stressed animals can induce laminitis. Although some wormers can precipitate laminitis, the most common group of drugs which cause laminitis in horses are the corticosteroids. Even injecting short acting corticosteroids into joints can cause severe laminitis.
Ensure your vet is fully aware of any laminitis history. Don’t be afraid to remind them before they inject your horse, especially if it is a vet new to your horse or one that hasn’t seen your horse for a while.
- Mechanical Trauma in Horses
Concussive laminitis (or road founder), is when horses are subjected to fast or prolonged work on hard surfaces. They may develop laminitis as a result of trauma to the laminae, particularly if their horn quality is poor.
Weightbearing laminitis is similar - when the horse is severely lame on one leg and has to put all their weight on the contra-lateral limb they often suffer from founder in the weightbearing limb. This is particularly common in hind feet.
- Equine Hormonal Issues
Hormonal imbalances in your horse, such as Cushing's Disease, can be harder to address as an owner and you will need support from your vet. Cushing’s Disease is a condition which follows an abnormality affecting the pituitary gland in the horse's head. Symptoms can include
Hypertrichosis (long, curly hair )
Delayed haircoat shedding.
Change in body conformation (muscle wasting and rounded abdomen or “potbelly”)
Decreased athletic performance.
Change in attitude/lethargy.
Fat deposits, especially along the crest of the neck and over the tail head.
Not all symptoms have to be seen for a horse to suffer from Cushing’s. All Cushing's cases are at greater risk of laminitis. If you suspect your horse may have Cushing’s, do not hesitate to contact your vet who will take a blood sample for testing.
Animals which are "good doers" may have Hypothyroidism or have an abnormal peripheral cortisol enzyme system, also known as obesity related laminitis or peripheral Cushing's disease. Others develop laminitis when they are in season.
Insulin resistance is another hormonal cause of laminitis. It is an endocrinopathic cause, causing hypoxia and inflammation in the lamella.
- Digestive Imbalances in Horses and Toxaemia
Recent research has highlighted how much the digestive system plays a major role in horses prone to laminitis. Laminitis caused by overeating could also fall into this category.
It isn’t necessarily the sugar in the horse’s diet that causes the laminitis, but what happens to that sugar once in the body. If it reaches the hind gut it will begin to ferment. Excessive sugar can also increase the foregut pH - this can allow pathogenic bacteria into the hindgut where it can upset the delicate microbe population, which is essential for the horse to break down its natural forage diet.
Such imbalances can lead to endotoxemia. This is where the pathogenic bacteria leaches from the horse’s gut into the blood supply. As this condition progresses, it can be a direct cause of laminitis. Toxaemia caused by the ingestion of plant or chemical toxins can have the same effect.
Other contributors to laminitis include stress (such as travelling or separation), worming, and vaccinations.
The Signs of Laminitis
The most recognisable symptom of animals suffering from laminitis is the characteristic ‘standing on their heels’. This is where they are leaning back onto the heels in order to take the weight off their painful toes. Damage has already been done by this point. Action needs to be taken before this stage.
Strong pounding digital pulses and hoof sensitivity are often the first signs of laminitis.
Other signs may include:
Heat felt in the hoof wall
Reluctance to move or lying down
Lameness, stiffness, foot sore, general change in gait
Shifting of weight or restlessness
Sweating and blowing; may appear colicky
Pus in the foot
Treatment & Prevention of Laminitis
- If your horse or pony has laminitis, remove them from any grazing and confine them to a deeply bedded stable and contact your vet immediately. Ensure you discuss the horse’s forage requirements whilst restricted from grazing.
- Make sure your horse’s diet is high in fibre and low in sugar, starch and fructans. Most working ponies do not need the various cereal mixes available on the market. They are able to work well on a natural forage-based diet, supported by a suitable balancer or a vitamin & mineral supplement.
- Feed clean, low nutritive value hay. Even a laminitic requires the correct amount of forage every day.
- If and where possible, opt to leave one paddock, or a section of a paddock, unfertilised.
- If your horse or pony is overweight put him on an appropriate calorie-controlled diet and exercise programme. Use a specially designed muzzle to help prevent excessive grazing.
If you suspect your horse or pony has laminitis you need to see the vet straightaway – laminitis should be treated as an emergency. The cause of the laminitis also needs to be identified as it could be part of a larger medical issue such as Cushing’s disease or an infection.
Remember, laminitis does not just affect the front feet. Only the hind feet may be involved or indeed it may only affect one foot.
This article is not intended to give medical advice. Consult your vet if you feel that your animal is unwell in any way.