Genetic Health Risks: Equine Metabolic Syndrome and Laminitis

Equine Metabolic Syndrome (EMS) is a widespread issue among horses, especially in certain breeds like ponies. It is primarily characterized by hyperinsulinemia—excess insulin in the blood that is not appropriately balanced by glucose levels. This metabolic disorder is often associated with obesity, making it difficult to manage without careful attention to diet and exercise. In severe cases, EMS can lead to secondary complications, most notably laminitis, a painful and potentially life-threatening condition that affects the hooves. Research has shown that a horse’s genetics also play a role in a horse’s susceptibility to EMS and laminitis. With DNA testing from Etalon Equine Genetics, you can find out if your horse is at an increased risk.

Key Takeaways:

• EMS is a metabolic disorder marked by elevated insulin levels and is often seen in obese horses.
• Horses with EMS are at high risk for developing laminitis, a painful and debilitating hoof condition.
• Genetics plays a role in EMS, with certain genetic variants linked to a higher risk of obesity and laminitis, especially in horses that are overweight.
• Early detection, including genetic risk testing, can help prevent EMS from worsening and reduce the risk of laminitis.
• Managing EMS involves diet control, exercise, and proactive veterinary care.

What Is Equine Metabolic Syndrome?

Equine Metabolic Syndrome (EMS) is a condition where the body’s insulin regulation is impaired, leading to elevated insulin levels in the blood. This typically occurs in obese horses or ponies, although horses of any size can be affected. EMS often goes undiagnosed for long periods because its symptoms overlap with other conditions, such as Cushing’s disease (pituitary dysfunction). The most common symptoms include obesity, fatty deposits (especially around the neck, shoulders, and tailhead), and increased fat around the internal organs. EMS horses are also at an increased risk of developing laminitis, a debilitating disease that affects the hooves and can cause permanent damage or lameness.

Symptoms and Diagnosis of EMS

Identifying EMS early is crucial to prevent its progression into more severe health issues like laminitis. The signs of EMS can be subtle, and often most often include:

Obesity: EMS horses often have a body condition score of 6+. They tend to easily gain weight and struggle to lose it. Learn how to assess your horse’s body condition score here.

Fatty Deposits: Particularly noticeable at the tailhead, crest, and behind the elbows. Geldings will sometimes present with fatty deposits in their sheath, whereas mares may have them around their mammary glands.

Laminitis: Episodes of painful inflammation in the hooves, particularly following changes in diet or stress.

Other symptoms include:

• General lethargy
• Increased thirst and urination
• Changes in appetite
• Loss of muscle mass
• Exercise intolerance
• Infertility

Because EMS can be mistaken for other conditions like Cushing’s, working with a veterinarian is essential for proper diagnosis. Blood tests, especially those measuring insulin levels, are often used to diagnose EMS.

The Role of Diet and Exercise

While there are few medical treatments for EMS outside of diet management, dietary control is crucial. A low-sugar, low-starch diet combined with regular exercise can help manage the condition. However, prevention is key—if obesity becomes severe, it’s harder to reverse and manage the condition. That's why early detection and proactive management are essential to preventing the development of laminitis and other related issues.

Genetic Risk Factor for EMS and Laminitis

While environmental factors like diet are crucial, genetics also plays an important role in EMS and its associated risks. A genomewide association study (GWAS) in Arabian horses revealed a genetic component to EMS and its link to laminitis.¹ Researchers found significant genetic markers near a gene, known as FAM174A, that could be involved in cholesterol homeostasis. Interestingly, this gene was also found to be connected to an increased risk of laminitis in horses who were overweight or obese. The risk of laminitis was found to be up to 9 times higher in horses with one or more genetic variants linked to this condition.

This suggests that EMS may not only be influenced by lifestyle factors like diet and exercise but also by genetic predispositions that make some horses more prone to developing laminitis when they carry excess weight.

Understanding your horse’s genetic predisposition can help you take preventative measures. Testing for these markers can provide insight into whether your horse is at higher risk of developing EMS, allowing you to adjust their diet and management practices.

Genetic Testing for EMS and Laminitis Risk

At Etalon Equine Genetics, we offer DNA testing to help identify genetic markers linked to EMS and laminitis. Testing can help determine if your horse carries any of the risk genes associated with these conditions. Results may indicate higher or lower risk based on the presence or absence of the EMS risk variants.

EMS/EMS = homozygous for Equine Metabolic Syndrome, at risk for EMS and increased risk for EMS-related laminitis

EMS/n = heterozygous for Equine Metabolic Syndrome, at risk for EMS and increased risk for EMS-related laminitis

n/n = no variant detected

With this knowledge, horse owners can make informed decisions about their horse's diet, exercise, and overall management to reduce the risk of EMS and its complications, including laminitis.

Conclusion

Understanding Equine Metabolic Syndrome (EMS) and its connection to laminitis is vital for maintaining the health of your horse. With advances in genetic testing, owners can now gain valuable insights into their horse’s risk factors, enabling better management of this increasingly widespread condition. If you are curious to know if your horse is genetically predisposed to developing EMS and laminitis, we recommend purchasing our Health Panel. This comprehensive DNA panel will provide you with your horse’s EMS risk plus more than 30 other health conditions and risks. By combining knowledge of your horse’s unique DNA, early detection, proper diet, and targeted management strategies, you can protect your horse from the painful and potentially life-altering effects of EMS and laminitis.

References ¹ Lewis, S. L., Holl, H. M., Streeter, C., Posbergh, C., Schanbacher, B. J., Place, N. J., Mallicote, M. F., Long, M. T., & Brooks, S. A. (2017). Genomewide association study reveals a risk locus for equine metabolic syndrome in the Arabian horse. Journal of animal science, 95(3), 1071–1079. https://doi.org/10.2527/jas.2016.1221