Testing for insulin dysregulation after transportation could lead to a false positive result

(c) Anna Cvetkova Dreamstime.com

Recent research indicates that conducting tests to identify insulin dysregulation (ID) in horses after transportation may lead to false positive results.

The oral sugar test (OST) is commonly used to assess insulin dysregulation, a key component of equine metabolic syndrome (EMS). This test involves taking blood samples at specific intervals before and after administering a dose of sugar, typically in the form of corn syrup. By analysing blood glucose and insulin levels, the OST evaluates how the horse’s body processes a sudden intake of sugar.

 

As this is a time-consuming test, it is often more practical to perform it in a clinic setting. However, recent findings have shown that transportation may influence test outcomes, potentially leading to false positives—where a horse with normal insulin function appears to have ID.

 

Dr. Erica Jacquay and Dr. Amanda Adams from the University of Kentucky, in collaboration with the WALTHAM™ Equine Studies Group, conducted a study to examine the effects of short-term transportation on stress parameters and insulin responses to the OST in horses both with and without ID. The research was recently published in the Equine Veterinary Journal.

 

The study involved seven non-pregnant ID mares and seven non-pregnant non-ID mares, all experienced with transportation. The horses were transported in groups for approximately 1.5 hours to and from their home base by the same driver. An OST (0.15 mL/kg body weight Karo Light Corn Syrup) was conducted 24 hours before and 3 hours after the journey.

 

The findings revealed that both serum and salivary cortisol levels significantly increased due to transportation, with no differences observed between ID and non-ID horses. As expected, the ID mares showed higher insulin responses to the OST on both occasions. 

 

However, in 5 out of 7 non-ID mares, post-travel OST insulin levels surpassed the diagnostic threshold for ID, suggesting that these horses could have been mistakenly diagnosed with insulin dysregulation. Additionally, some ID mares showed post-travel T60 OST insulin levels that were more than double their pre-transportation levels.

 

These results imply that real-world testing conditions, including transportation, may lead to misdiagnoses of insulin dysregulation and inappropriate classification of horses as having EMS.

 

“This research is an important step in improving our understanding of insulin dysregulation and EMS,” said Dr Pat Harris, head of the WALTHAM™ Equine Studies Group which provides the science behind the SPILLERS brand. “The findings show that performing an OST three hours after short-term transportation may result in inaccurate ID status, whether testing a new case or monitoring the status of an ID horse. In addition, special care should be given when transporting horses with ID especially those with a history of hyperinsulinaemia- associated laminitis.

 

“Further studies are needed to determine the best timing of diagnostic testing if transporting horses to a veterinary clinic for OSTs.”

 

For more details, see:

 

Jacquay ET, Harris PA, Adams AA. T

he 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

Could flatter saddles improve welfare in ridden horses?

(c) Nicole Ciscato Dreamstime.com

 A new study has indicated that flatter-shaped saddles may be more suitable for horses that
spend most of their ridden time in motion.

The research, which observed significant changes in the shape of horses' backs while stationary and during movement, found that horse backs become considerably flatter during motion compared to when they are standing still.

 

Back pain is common among ridden horses and is frequently linked to poor saddle fit. A properly fitted saddle is crucial for distributing the rider’s weight evenly and reducing pressure on the horse’s back.

 

Saddles are typically fitted to horses while they are stationary and then checking the fit by observing the horse in motion.

 

The research team, made up of experts from the Royal Veterinary College and the University of Southampton, used an advanced camera array to measure the saddle region of five horses' backs while standing, walking, and trotting. These measurements captured the differences in back curvature. To validate their observations, the researchers reconstructed a life-sized model of a horse using laser scans.

 

The findings are reported in the Journal of the Royal Society Interface.

 

The study confirmed that the shape of horses' backs is not static. Instead, it changes significantly, with certain areas deforming by several centimetres.

 

Despite notable deformations in some regions, the saddle area remained relatively stable during movement, showing only minor changes of a few millimetres. This suggests that the deformable padding in saddle panels is likely sufficient to accommodate these small variations.

 

The study also found that, among regions relevant to saddle fit, the withers exhibited the most movement. The withers elevated and depressed more than four times as much as other areas that could interact with an English saddle.

 

These findings emphasise the importance of ensuring proper withers clearance, as outlined in current saddle fitting guidelines, due to the significant mobility observed in this area.

 

This research provides a foundation for further studies into whether similar back-shape changes occur at faster gaits such as canter and gallop, and how a rider’s weight affects these changes. The team aims to test whether saddles fitted to horses in motion can better distribute pressure.

 

Dr Jorn Cheney, Lecturer in Natural Sciences at the University of Southampton and lead researcher of this study, said: “I am reassured that a lot of key principles of saddlery held true. At least during walk and trot, saddles can be stiff, and they cover areas of the back that don’t move. Now the exciting question is, ‘do we improve upon the design by fitting to the moving animal?’ and if so what’s the best way of making that technique accessible?”

 

The study was funded by a grant from the Worshipful Company of Saddlers.

 

For more details, see: 

 

Smirnova, K. P., Frill, M. A., Warner, S. E., & Cheney, J. A. (2024). 

Shape change in the saddle region of the equine back during trot and walk. 

Journal of the Royal Society Interface, 21(215).  

https:doi.org/10.1098/rsif.2023.0644