Testing after travelling could lead to a false diagnosis of EMS

New research selected as one of the most clinically relevant pieces of EVJ research published this month

New research*, conducted by the University of Kentucky in partnership with the SPILLERS™ brand, has shown that testing for insulin dysregulation, which is the core component of Equine Metabolic Syndrome (EMS), within three hours of travelling could lead to a false positive result for EMS. The work has been selected as one of the most clinically relevant pieces of research published in the Equine Veterinary Journal’s early view section this month.

The oral sugar test (OST) is a commonly used method of diagnosing insulin dysregulation (ID). It involves measuring the concentration of insulin in the horse or pony’s blood before and after consuming a set amount of sugar syrup given by syringe. 

Testing for insulin dysregulation, which is the core component of Equine Metabolic Syndrome (EMS), within three hours of travelling could lead to a false positive result for EMS.

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Insulin dysregulation is a major risk factor for laminitis. In fact, laminitis associated with a high concentration of insulin in the blood (hyperinsulinemia) is now thought to be the most common form of laminitis in the UK.

The research was conducted by Dr Erica Jacquay and Dr Amanda Adams from the University of Kentucky. It involved seven insulin dysregulated mares and seven non-ID mares, who were transported in groups for approximately 1.5 hours. An oral sugar test was completed 24 hours before and 3 hours after travelling. 

As expected, insulin levels in response to the OST were higher in the insulin dysregulated mares on both occasions, but the oral sugar test conducted after travelling also classified five out of seven non-ID mares as insulin dysregulated. This suggests that in a ‘real life’ situation, some horses may have been misdiagnosed as having insulin dysregulation and be falsely considered as having EMS.

The core factor linking EMS to an increased risk of laminitis is having insulin dysregulation rather than being obese. Whilst being obese increases the risk of being insulin dysregulated; importantly, lean horses and ponies can be ID too, meaning it is really important to test, if concerned, regardless of body condition. The term ‘EMS’ was first coined in the early 2000s and, although knowledge has improved greatly, there’s still a lot we need to learn. Improving our understanding of insulin dysregulation, including how to diagnose it more accurately, is key to improving our ability to identify and manage those at greatest risk of laminitis. 

“Veterinary assessments and investigations can be time-consuming, expensive and stressful (for horses and their owners!),” said Sarah Nelson Product Manager at Mars Horsecare, home of the SPILLERS brand. “If you need to take your horse to the vet, as opposed to the vet visiting you, ticking multiple things off the list in one visit can certainly make sense in some situations. However, this research shows that, when it comes to testing and monitoring for ID/EMS, we may need to rethink our strategy, as testing after travelling may lead to a false diagnosis.”

The research abstract (short summary) is published in the Equine Veterinary Journal and can be viewed for free here.

References

*Jacquay ET, Harris PA, Adams AA. The impact of short-term transportation stress on insulin and oral sugar responses in insulin dysregulated and non-insulin dysregulated horses. Equine Vet J. 2024. https://doi.org/10.1111/evj.14403