The recording of a webinar with Rossdales vets Lucy Grieve and Emily Floyd and Dengie Horse Feeds nutritionist Katie Williams from 17 May 2022.
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Vet Edd Knowles, currently at Bell Equine, completed his PhD at the RVC in 2021.  His research showed that testing insulin, both resting and after an oral sugar test using Karo Light corn syrup, was the best way to identify ponies that would develop laminitis.  Other factors identified by Knowles that can help identify horses at risk of laminitis include level of exercise, body condition score/body fat and hoof changes - although hoof changes (related to laminitis such as divergent hoof rings) will follow laminitis, not precede it.

Knowles' research was published in the EVJ September 2021 special issue for BEVA 2021 clinical research abstracts:
​Knowles EJ, Elliott J, Harris PA, Menzies-Gow NJ
Predictors of laminitis development in non-laminitic ponies
Equine Veterinary Journal August 2021 Vol 53 Issue S55 Clinical Research Abstracts of the BEVA Congress 2021​ p21-22.  https://doi.org/10.1111/evj.31_13492

and as a full paper in the EVJ in March 2022:
​Knowles EJ, Elliott J, Harris PA, Chang YM, Menzies-Gow NJ.
Predictors of laminitis development in a cohort of non-laminitic ponies.
Equine Vet J. 2022 Mar 9. doi: 10.1111/evj.13572. Epub ahead of print. PMID: 35263471.

374 ponies were monitored for up to 4 years (giving 891 pony years - 891 pony years/374 ponies = an average of 2.4 years that a pony was followed for).  The ponies were considered non-laminitic when they entered the study.  Every 6 months blood was collected for measurement of basal ACTH, adiponectin, triglycerides, glucose and basal non-fasted insulin (T0), and an oral sugar test was carried out 60 minutes (T60) after administering 0.3 ml/kg bodyweight (rather than the standard 0.15 or 0.45 ml/kg) Karo Light corn syrup.  Insulin was measured using a Tosoh AIA-360 Fluorescence Enzyme Immunoassay.

4.8 ponies developed laminitis per 100 pony years, or per 100 ponies/year.  The ponies were divided into 3 groups - low, medium and high risk of laminitis depending on their basal T0 and 60 minutes after Karo Light corn syrup (T60) insulin results.

Measured factors that were associated with the development of laminitis included basal insulin, insulin 60 minutes after giving Karo Light corn syrup, adiponectin, and evidence of divergent hoof growth.  Divergent hoof rings are a sign of chronic laminitis - at The Laminitis Site we have only seen divergent hoof rings where there is palmar rotation and usually (at least at some point) dorsal rotation and signs of compression in the toe wall/coronary band, therefore we would argue that seeing divergent hoof rings shows that a pony has already had laminitis, and is not predictive of future laminitis.  Seeing divergent hoof rings means that x-rays should be taken to assess and guide the realignment of rotation/misalignment between pedal bone and hoof capsule.

ACTH was not associated with laminitis.

The 3 risk groups were:
Low: non-fasted basal insulin <21.6 uIU/ml, 70% of the population were in this group, so 261.8/374 ponies, incidence of laminitis was 6% in this group over 4 years.
Medium: non-fasted basal insulin 21.6-45.2 uIU/ml, 20% of the population were in this group, so 74.8/374 ponies, incidence of laminitis was 22% in this group over 4 years.
High: non-fasted basal insulin >45.2 uIU/ml, 10% of the population were in this group, so 37.4/374 ponies, incidence of laminitis was 69% in this group over 4 years.


Under Main limitations the abstract says "Results may not apply to different insulin assays...".

Questions:
How does the Tosoh AIA-360 Fluorescence Enzyme Immunoassay compare e.g. to Immulite 2000 results?  Was this assay validated for equine insulin?  
What did the ponies eat before their basal non-fasted insulin blood collections?

Listen to The Humble Hoof's podcast Laminitis: Treatment and Prevention with Dr Alicia Nolfi.  Dr Nolfi discusses laminitis treatment, and the importance of preventative care.

Laminitis: Treatment and Prevention Podcast

The link between insulin dysregulation, obesity and laminitis in horses - Prof. Simon Bailey, University of Melbourne

Webinar: How to provide a good life for horses: friends, freedom and forage
Hosted by World Horse Welfare on 26 May 2021

The Latest on EMS, PPID & Laminitis
Webinar by Jamie Prutton from Liphook Equine Hospital and Tracey Hammond from Dengie Horse Feeds on 31 March 2021, hosted by Dengie Horse Feeds

Dengie brought out a new Laminitis Guide in March 2020, which features photos taken by The Laminitis Site of some of the many laminitis cases that TLS has helped.  Dengie very kindly provided The Laminitis Site with Dengie feed vouchers as a thank you - for which rescued laminitic pony Dolly will be very pleased, as she loves Dengie HiFi molasses free!

The researchers concluded that supplementation with a mixture of straw and hay is a safe, cost-effective means of supporting weight loss in grazing ponies kept in groups.

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If feeding straw:
Ensure teeth have been checked and function well.
Introduce straw gradually, as with all feeds.
Feed barley or oat straw, ideally not sprayed with chemicals and of good hygienic quality.
Feed no more than 50% of the total forage amount as straw.  NB Pat Harris suggests feeding no more than 25% of the total forage amount as straw.

Laminitis is generally treated and managed by:
1 restricting movement, pain relief and supporting the feet,
2 therapeutic trimming [TLS would argue that shoeing is almost never the best option, and realigning trimming should be part of the initial care], and diagnosis/treatment/management of hormonal disorders,
3 ongoing management of the horse's diet, exercise and footcare.

Laminitis prevention:
​WHW suggest that important risk factors for laminitis include recent weight gain, a history of laminitis and foot soreness after shoeing/trimming.  Ensuring a horse is not overweight is very important for preventing laminitis.  A history of laminitis tells you that they almost certainly have a hormonal condition (EMS / PPID) that needs to be managed/treated, and chronic laminitis to be corrected.  Foot soreness after shoeing/trimming is often seen in horses that have had laminitis that haven't had their feet correctly realigned and supported/protected - often it is foot pain from chronic (uncorrected) laminitis that is seen when horses appear to have recurrent, and not necessarily new laminitis (linked to abnormal hormone production).

The proceedings from the Global Equine Endocrine Symposium held in Germany in January 2020 are available here.