a horses hoof on a stone floor with an xray image imposed over the top

Laminitis in Horses

The proportion of horses and ponies affected by laminitis has been reported to be between 1.5 and 34% in papers published in peer-reviewed journals. These numbers include studies from around the world and largely relate to cases diagnosed by veterinary surgeons. The last time (2018) the Blue Cross National Health Survey was conducted in the UK, the prevalence of laminitis was reported to be 5.3%. Just over 5500 people took part in the survey and gave information about nearly 14 000 horses which is the largest scale epidemiological study data available in the UK. It is worth noting that many cases of laminitis are not reported to vets and many horses and ponies have repeat episodes so the frequency of laminitis may even be greater in some equine populations.

Being overweight increases the likelihood of a horse or pony developing laminitis and, as equine obesity is a significant issue in the UK, many horse owners will unfortunately encounter laminitis. It can be a distressing, costly and time-consuming disease to manage which is why the levels of equine obesity are so concerning. If you are concerned about laminitis or are managing a horse or pony with the disease, we recommend also reading our advice on weight management too as this will be key for their long term management and care.

What is laminitis?

The layer of tissue which connects the hoof wall to the pedal bone is known as the laminae. Laminitis occurs when the laminae becomes inflamed (itis) which results in severe pain as the hoof wall is obviously rigid and so doesn’t expand to accommodate the swelling. In severe cases, the connection between the laminae and the pedal bone fails allowing it to rotate down which may be referred to as foundering. The pedal bone may even penetrate through the sole of the hoof in very severe cases.

Signs and symptoms of laminitis in horses

The disease is more commonly seen in the front feet and horses suffering from laminitis often adopt a classic stance of rocking back onto the hind legs to take the weight off the front feet. The horse often also tries to push his weight onto his heels as the toe area is typically the most painful. The horse will be reluctant to move and will shift their weight from one leg to another. The lameness is more pronounced on hard ground and when turning.

laminitis ridges on horses hoof

A pounding digital pulse is often highlighted as a symptom of laminitis. This can be felt at the back of the fetlock on either side where a group or bundle of blood vessels can be felt. It is worth familiarising yourself with how a normal pulse feels so you can tell when it is more pronounced and therefore an indication of laminitis.

Inflammation is usually accompanied by heat, so if your horse’s feet feel hotter and other symptoms are evident then you should call your vet without delay. Acting fast is most likely to reduce the severity of symptoms and increase the chances of a full recovery.

Causes of laminitis

The causes of laminitis are generally grouped into 3 categories which are:

  • Mechanical stress/overload – excessive weight bearing is thought to disrupt the blood supply to the laminae resulting in inflammation. This is most common when the horse has an injury in one limb and is shifting its weight to the other limb.
  • Inflammatory diseases such as placentitis, and septicaemia – the exact disease process is not fully understood but inflammation in other parts of the body seems to trigger inflammation in the laminae too
  • Endocrine (hormonal) diseasePPID and EMS are two diseases that cause hormonal changes in the body which predispose the horse to laminitis.

The relationship between diet and laminitis

The excessive ingestion of non-structural carbohydrates (NSC) such as starch and sugar has long been recognised as a cause of laminitis. Research models based on an NSC overload have been used in studies in the past to try to learn more about the disease process and yet many questions still remain unanswered. It is known, however, that excessive consumption of NSC means it cannot all be absorbed in the small intestine and so reaches the horse’s hindgut. Here it is rapidly fermented by the microbiota to produce more acidic short chain fatty acids than would be produced by fibre fermentation. The hindgut becomes more acidic resulting in the death of bacteria that cannot tolerate the increased acidity. This is also termed dysbiosis and may be accompanied by loose droppings or diarrhoea.

The increased acidity also increases the permeability of the hind gut allowing pathogenic substances to escape from the gut into the body that wouldn’t normally be able to do so in a healthy gut. It is thought that bacterial endotoxin escaping from the gut may play a role in triggering inflammatory changes in the body. It is also worth noting that low fibre diets, with or without NSC reaching the hindgut, have also been shown to increase gut permeability in other species. This is another reason why we strongly advocate feeding a minimum of 1.5% of bodyweight as forage every day.

Recently a lot of attention has been focused on endocrinopathic laminitis e.g. those occurring in horses with EMS or PPID. It is now known that hyperinsulinaemia (high levels of insulin) can cause laminitis without the need for an overload of NSC. Given the high levels of obesity and EMS in many equine populations, it is no surprise that this is regularly cited as the most common cause of laminitis.

Whatever the cause, the advice remains to remove feeds containing high levels of NSC from the ration immediately and a low NSC ration is likely to be needed for the future management of any horse or pony that has previously had laminitis.

Microbial dysbiosis and laminitis

Several studies highlight differences in the microbiota both in terms of diversity and number of different bacteria in the digestive tracts of apparently healthy horses and those with diseases such as laminitis. The question remains however, as to whether the changes contribute to the development of disease or occur as a result of disease. Studies relating to gastrointestinal microbiota are notoriously difficult as it is known there is considerable natural variation between horses and within the same horse especially at times of stress such as exercise, travel and dietary change.

SGLT2 Inhibitors for Horses

Canagliflozin and etugliflozin are new medications for horses with EMS. In September 2024 a group of leading vets published a letter in the Vet Record highlighting concerns about a number of cases of hyperlipaemia developing as a result of the use of SGLT2i medications. Due to these incidents the vets issued the following recommendations:

“the medications are used only in horses that have failed to respond adequately to appropriate dietary and exercise management or those with significant active laminitis” and “owners should be informed of the potential adverse effects and be counselled to be vigilant for the clinical signs of hyperlipaemia.”

In response to this we have compiled a checklist for all the dietary management and other actions that we believe can and should be taken before resorting to medication. Click here to view the checklist.

Reducing the risk of laminitis

The following are top tips for trying to reduce the risk of laminitis:

  • Keep your horse or pony at a healthy weight
  • Ensure your horse receives at least 1.5% of bodyweight as forage per day – use more of a low calorie fibre source than less of a higher calorie
  • Minimise or avoid cereal based feeds to help reduce the risk of insulin dysregulation
  • Use high quality fibre and oil to provide additional energy for weight gain or exercise if needed
  • Ensure a balanced diet is provided – low NSC options such as supplements and balancers are ideal
  • Slow the rate of intake using straw both in the forage ration and the bucket feed – this helps to reduce the insulinaemic response
  • Provide increased antioxidant support to help counter a reduced anti-inflammatory state associated with laminitis
  • Ensure your farrier visits regularly to maintain good hoof conformation
  • Consult with your vet if your horse is on box rest due to an injury – consider if there is a risk of supporting limb laminitis and provide a deep, supportive bed when stabled.

Laminitis risk calculator

There are lots of different factors that increase a horse or pony’s risk of developing laminitis. We have developed a questionnaire to help you ascertain your horse’s risk level and identify which areas are the greatest risk

Complete our laminitis questionnaire

References

FAQs

Does cryotherapy help those with laminitis?

One study has shown that there was a reduced incidence of laminitis in horses with colitis who received cryotherapy before any signs of laminitis were apparent. A subsequent study has shown that digital hypothermia reduced the severity of damage to the laminae when initiated at the acute onset of lameness. The key is for the cold treatment to be started very early and ideally before the onset of any clinical signs of laminitis. You should consult your vet if you are concerned about laminitis and cold treatment is certainly not an alternative to veterinary treatment.

Why do some feeds marketed for horses prone to laminitis contain molasses?

Molasses itself is not dangerous or harmful to horses – it has been used as an ingredient in horse feeds for decades. It is a source of sugar and if used in large amounts, can significantly increase the amount of sugar a horse consumes. The key point is how much molasses is added to a feed and how much sugar the other ingredients contain – this determines the overall sugar content and therefore suitability of a feed for a horse or pony prone to laminitis.

How long does it take for a horse to recover from laminitis?

The recovery process varies between individuals but it takes weeks to months for a horse to recover. You should consult your vet regularly and before re-introducing exercise. It is important not to move a horse unnecessarily when they have laminitis as this can increase the damage to the laminae. You should also liaise with your vet and farrier in relation to what remedial shoeing might be beneficial and the use of pads and support for the feet as part of their recovery. Consult a nutritionist about longer term nutrition and feeding management.

How do I put weight on my laminitic safely?

The key is to use horse feeds that are low in sugar and starch which usually means they contain higher levels of fibre and oil which are safer sources of energy. High or long term feeding of sugar and starch based feeds are increasingly being linked to insulin dysregulation (ID) which is a predisposing factor to laminitis. Be careful that you don’t over-condition your horse as the greatest risk factor for laminitis in horses is being overweight. Unfortunately, “fat” is becoming normal – research has shown that horse owners frequently underestimate the condition score of their horse meaning they are underestimating their risk of laminitis too. If you are in any doubt, ask a nutritionist to assess your horse and don’t succumb to peer pressure to have a cuddly pony – cuddly might be cute but it isn’t healthy!