Laminitis is a serious, painful and sadly common condition, which can affect any horse, pony, donkey or mule. The condition accounts for around 15% of lameness cases in the USA, and 10% in the UK. It is caused by inflammation of the laminae, which are the tissues that connect the hoof wall to the third phalanx (coffin/pedal bone). Whilst laminitis is usually associated with a hormonal disorder (e.g. PPID / Cushing’s), it can have a number of contributing factors.
This blog article covers what laminitis is, the causes of laminitis and laminitis prevention.
Note: Laminitis is a veterinary emergency. Always call your vet straight away if you suspect that your horse or pony has laminitis.
What is Laminitis in Horses?
Laminitis is a condition that occurs when the laminae - the sensitive tissues within the hoof - become inflamed. The laminae support the pedal bone within the hoof capsule, but if they are inflamed they can come apart, resulting in movement or rotation of the pedal bone.
Laminitis will not resolve on its own and early intervention is needed to prevent treatable, acute cases from evolving into chronic laminitis, which is harder to manage and can affect a horse’s quality of life long-term.
Whilst many horses and ponies do recover from laminitis, severe and / or recurrent cases can leave euthanasia as the only humane option. Therefore, it is crucial that horse owners take steps to prevent laminitis and minimise the risk of recurrence in horses that have previously had laminitis.
What Causes Laminitis?
There are a number of factors that can cause or contribute to laminitis. Equine Metabolic Syndrome (EMS) and Cushing’s Disease / Pituitary Pars Intermedia Dysfunction (PPID) are major underlying causes, as is obesity. Disruption of the hindgut due to the overconsumption of starch or fructans is another major contributing factor. This section outlines some of the main causes of laminitis:
Underlying metabolic dysregulation (EMS / PPID)
Overconsumption of starch or fructans
Obesity, injury and other factors
Underlying Metabolic Dysregulation (EMS / PPID)
Around 90% of laminitis cases are caused by an underlying hormonal disorder. Equine Metabolic Syndrome (EMS) and Pituitary Pars Intermedia Dysfunction (PPID / Cushing’s Disease) are the two conditions most commonly associated with laminitis. EMS is an inability to regulate insulin, whereas PPID is an age-related condition that affects the pituitary gland. PPID can also disrupt insulin regulation.
Horses with EMS and laminitis have a different microbiome profile to those horses with laminitis caused by the overconsumption of starch/fructans. You can find out more about EMS and laminitis in our blog article: How the Loss of Biodiversity in the Horse's Environment Can/Does Affect/Help Cause the Onset of EMS/Obesity and Laminitis.
If you suspect your horse may have either of these conditions, contact your vet. They can advise you on diagnostic tests, as well as treatment and management options.
Disruption of the Hindgut due to the Overconsumption of Starch or Fructans
Carbohydrate overload can also trigger laminitis. Starchy and sugar-rich feeds can cause this, as can gorging on sugar-filled spring grass.
Laminitis caused by a gastric disturbance is thought to be from the overconsumption of starch (cereal or grass) and fructans (grass). Undigested food overflows from the small intestine into the hindgut, where it causes a rapid disruption to the bacterial community and an increase in the production of lactic acid.
During this event, there is evidence to show an increase in the percentages of Lactobacillus and Streptococcus and an increase in potential pathogens Veillonella and serratia (Tuniyazi et al, 2021).
At the same time, there is a decrease in species richness and diversity, with a clear separation between healthy horses and those with laminitis largely identified through the increase in lactobacillus.
Lactobacillus produces lactic acid. As levels rise there is a corresponding increase in bacteria that utilise lactic acid (Megasphaera) and a decrease in bacteria that are unable to survive in an acidic environment ie. Fibrobacter, Phascolarctobacterium, Papillibacter, and Alloprevotella. The reduction of core members of the microbiome causes discomfort, instability, and gastric sensitivity.
You can find out more about the relationship between starch overload and laminitis (acidosis laminitis) in our blog article: All You Need to Know About Acidosis Laminitis).
Other Contributing Factors to Equine Laminitis
There are a number of other factors that can contribute to laminitis. Overweight horses and ponies are also at a much higher risk of developing laminitis. Sudden weight gain in particular can more than double the risk of laminitis. Furthermore, horses and ponies that have had one bout of laminitis are more likely to suffer from recurrent episodes. Laminitis can also arise when one limb is having to bear excessive weight. This may be due to an injury in the opposite limb, for example.
Reducing the Risk of Laminitis
When it comes to laminitis, prevention is far better than cure. Good management, a balanced high-fibre, low-starch diet and maintaining a healthy weight are all important to preventing laminitis. Early diagnosis and careful management of PPID or EMS is vital to preventing laminitis, as these metabolic disorders are the number one cause of laminitis.
Supporting the hindgut involves feeding the right balance of nutrients for a diverse and healthy microbiome. Learn more about how to manage your horse’s diet for a healthy microbiome in our article: The Role of the Microbiome in Equine Laminitis.
What to do if You Suspect Your Horse or Pony has Laminitis
Laminitis is a veterinary emergency. Therefore, if you suspect laminitis, you should always call your vet immediately. If your horse is able to walk, try to move them to a nearby stable or shelter and provide them with a deep bed of shavings to help support the hooves. Alternatively, try to make them comfortable where they are by providing bedding in situ. Ensure the horse has access to fresh water, but remove access to food.
Laminitis is a very painful condition that can result in lasting damage if it is not treated quickly. Whilst laminitis is usually treatable, severe cases can result in the need for euthanasia.
How the EquiBiome Test Can Help
Many of our customers come to us because their horses are laminitic and despite their very best efforts with managing their diets, the laminitis reoccurs. Whilst we cannot prevent, treat or cure laminitis, our tests can provide useful insights into the horse’s gut health, which may be linked to laminitis among many other conditions. You can find out more about how the EquiBiome Test has helped owners of laminitic horses and ponies by reading some of our case studies:
The EquiBiome Test identifies the numbers and types of bacteria that are present in the horse’s hind gut using a faecal sample. Using state of the art MiSeq NGS technology, we can produce a snapshot of the internal microbial community. The results are presented in the easy-to-understand EquiBiome Report, which horse owners can use to make more informed decisions regarding what and how to feed their horses. Visit our online shop to order your EquiBiome Test Kit today.
Note: EquiBiome is not intended to diagnose, prevent, treat or cure any condition.