A study published in the Equine Veterinary Journal has concluded that Insulin dysregulation (ID) status in ponies cannot be determined solely by observation of body condition1 .

Factors associated with insulin responses to oral sugars in a mixed-breed cohort of ponies was carried out by Edd Knowles and colleagues at the Royal Veterinary College in collaboration with the WalthamTm Equine Studies Group. 
For the study, a total of 1763 oral sugar tests (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.2 
Lead author Edd Knowles said: “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.3
References 
  1. Knowles EJ, Harris PA, Elliott J, Chang Y-M, Menzies-Gow NJ. 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
  2. N.R. Liburt, S.L. Mastellar, E.R. Share, P.A. Harris. How challenging is it to find non-insulin dysregulated horses in an apparently clinically healthy herd of university horses? Journal of Equine Veterinary Science. 2023; 124. https://doi.org/10.1016/j.jevs.2023.104389.
  3. Bamford, N ; Potter, S ; Baskerville, C ; Harris, P ; Bailey, S Influence of dietary restriction and low-intensity exercise on weight loss and insulin sensitivity in obese equids J Vet Intern Med. 2019. 33:280- 286