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Writer's pictureCarol Hughes

Equine Metabolic Syndrome in Horses

Equine Metabolic Syndrome (EMS) is a common condition, especially in older horses and ponies. It can be difficult to manage. This blog article outlines the symptoms of EMS, how the condition can be managed, and the link between Equine Metabolic Syndrome and the equine hindgut.


What is Equine Metabolic Syndrome in Horses?


Equine Metabolic Syndrome in horses (EMS) refers to metabolic and hormonal imbalances, which lead to increased susceptibility to obesity, insulin resistance, and laminitis. The condition is characterised by abnormal fat distribution, heightened insulin levels, and an elevated risk of serious health complications such as laminitis. 


What Are the Symptoms of EMS?


Equine Metabolic Syndrome is usually observed in overweight individuals. It can lead to various health issues, and prompt recognition is vital for proper management. The main symptoms of EMS are:


  • Obesity

  • Insulin Resistance - insulin is a hormone crucial for glucose regulation

  • Laminitis

  • Abnormal Fat Distribution and Fat Pads - particularly in the crest of the neck, along the shoulders and around the top of the tail

  • Irregular Glucose Levels - due to insulin resistance

  • Increased Appetite

  • Lethargy

  • Increased sensitivity to grazing, leading to metabolic disturbances

  • Altered coat texture or difficulty in shedding winter coat


It's important to note that not all horses with EMS exhibit the same symptoms, and the severity can vary. If you suspect EMS, you should contact your vet for an accurate diagnosis and a tailored management programme.


How is EMS Managed?


Equine Metabolic Syndrome in horses is typically managed through a combination of dietary modifications, controlled exercise, and weight management. Implementing a low-starch, high-fibre diet, regular physical activity, and monitoring insulin levels all form part of the standard approach to managing EMS. Additionally, administering medications to improve insulin sensitivity and regulating pasture access may also be used to manage the condition.


The Link Between Equine Metabolic Syndrome and the Hindgut 


​​New technology allows us to identify important mechanisms linking the gut bacteria and host responses, which lead to conditions such as EMS. The chemicals made by the bacteria and the nutrients used by the bacteria also have a major effect.


The microbiome of horses with EMS is different from those without. One research paper found higher levels of planctomycetes in horses with EMS. Planctomycetes are a normal part of the microbiome, but they have been linked to gastric inflammation (colitis) in horses when present in high levels. Planctomycetes are strongly antibiotic resistant, with numbers increasing following a course of antibiotics use. Could antibiotics be a contributing factor to EMS?


You can find out more about the relationship between equine metabolic syndrome in horses and the gut bacteria in our blog article: Equine Metabolic Syndrome.


Why Are Native Ponies More Prone to Equine Metabolic Syndrome?


We know that native ponies, including Exmoors, Shetlands, and similar breeds are at a heightened risk of EMS and related conditions such as laminitis and obesity. But why is this?


Native ponies are bred to survive in harsh environments, such as bogs or moors. They are well-suited to these habits and continue to roam to this day. However, most domesticated horses and ponies now graze on pastures designed to fatten livestock such as cattle. Furthermore, the poor biodiversity of agricultural grazing compared with the high biodiversity of these ponies’ original habitats presents additional challenges for maintaining a healthy microbiome. 


You can find out more about the relationship between loss of biodiversity and EMS in native ponies in our article: Equine Obesity, EMS, Laminitis and Biodiversity - is There a Link?


How the EquiBiome Test Can Help


Many of our customers come to us because their horses have been diagnosed with EMS and they want to be better informed on what and how to feed their horses. Whilst we cannot prevent, treat or cure equine metabolic syndrome, our tests can provide useful insights into the horse’s gut health, which may be linked to EMS among many other conditions. You can find out more about how the EquiBiome Test has helped owners of horses and ponies with equine metabolic syndrome 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.

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