Tuesday, September 19, 2023

Insulin Dysregulation: not limited to overweight ponies

  

Body condition score alone does not reliably predict the risk of a pony developing laminitis
according to recent research. 

 

The study, by Edd Knowles, Post-doctoral researcher at the Royal Veterinary College (RVC) and Internal Medicine Specialist at Bell Equine Veterinary Clinic. with colleagues at the RVC, and Pat Harris of the Waltham Equine Studies Group, is published in the Equine Veterinary Journal.

 

The findings show that insulin dysregulation (ID), which is linked to an increased risk of laminitis, may occur in ponies across a wide range of body conditions, ages and levels of exercise, not just in those that are overweight. The study also showed that ID was less common in ponies that undertook more exercise, including low-intensity activities.

 

Insulin is a hormone produced by the pancreas. The release of insulin is the signal for cells, largely in muscle and liver tissue to absorb glucose (sugar) from the blood. Insulin dysregulation (ID) is a term that includes a high basal or ‘resting’ insulin (in the blood), an exaggerated insulin response to consuming starch and/ or sugar and tissue insulin resistance (a failure of cells to respond to insulin). 

 

An association between ID and laminitis is well-established, and early detection of ID is likely to be useful in helping to prevent the disease.

 

In this study, the concentration of insulin was measured in the blood of ponies before and sixty minutes after they were given, orally, a sugar syrup (an oral sugar test (OST)). 

 

A total of 1763 OSTs were taken from 367 non-laminitic ponies over four years. The ponies were visited and tested in the Spring and Autumn unless they developed laminitis. Various physical parameters were recorded at the time of each OST including weight, height, body length, neck length, heart girth, belly girth, body condition score and cresty neck score. Owners/carers were asked to complete a questionnaire concerning the specific characteristics, diet, management, duration and intensity of exercise and health for each pony at each visit. 

 

The study concluded that associations between InsulinT60 and physical and owner-reported variables were limited. Season, owner-reported and physical features only explained 10%– 27% of the differences in InsulinT60 risk status in the study population.

 

The findings support previous work that suggested body condition scoring alone was not sufficient to determine insulin dysregulation (ID) status and emphasises the value of using an oral sugar test to screen for ID status.

 

Lead author Edd Knowles stated: “Our work has shown that while physical and owner-reported features can be used to identify ponies with a higher risk of ID, veterinarians should not limit testing for ID to ponies in which these risk factors are present. Doing so would miss identifying ponies at moderate to high risk of laminitis.” 

 

The study also indicates that relatively small increments in equine exercise routines may be beneficial. 18% of samples from ponies that were reported to do no trotting exercise were in the high-risk InsulinT60 category compared with only 9% of samples from those reported to undertake 1–2 h of trotting per week. 

 

This finding supports earlier research, on the benefits of low intensity exercise, conducted in collaboration with the WALTHAM® Equine Studies Group, which provides the science behind SPILLERS®,

 

“This work confirms that while body condition is a useful indicator, we can’t simply assume that ponies with obvious physically apparent attributes such as excess weight are the only group likely to have ID,” said Sarah Nelson, Product Manager at Mars Horsecare, home of the SPILLERS brand. 

 

“We must consider multiple variables when targeting ponies for ID screening, in order not to miss those potentially at increased risk of laminitis, who may have a ‘healthy’ body condition score.” 

 

“The association with even low-level exercise is also an important practical management message for horse owners” she added.

 

For more details, see:

 

EJ Knowles, PA Harris, J Elliott, Y-M Chang, NJ Menzies-Gow.

Factors associated with insulin responses to oral sugars in a mixed-breed cohort of ponies. Equine Vet J. 2023.

https://doi.org/10.1111/evj.13983

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