Weight, insulin and laminitis

In the horse, weight, insulin and laminitis are closely linked — and many common assumptions are wrong. A few evidence-based insights.

Not every metabolic horse is fat — and some are lean

Equine Metabolic Syndrome (EMS) is often assumed to be a disease of overweight ponies. In reality, a good number of confirmed cases are horses in normal or even low body condition. The problem is how the horse handles insulin, not simply how much fat it carries — so insulin itself has to be measured to make the diagnosis.

Fat above the eye is a warning sign

Horses do not normally lay down fat in the small hollow above the eye. When you can feel fat there, it is a sensitive early marker of a metabolic problem — and it can only be found by standing in front of the horse and feeling both eye sockets. It is one of the strongest reasons a metabolic assessment needs to be done hands-on, in person.

The crest of the neck is fat — not muscle

There is no muscle on top of the neck above the nuchal ligament; a hard or large crest is stored fat. That fat is metabolically active and drives both insulin problems and laminitis risk. A firm crest on a native pony is a health signal, not just 'how the breed is built'.

Fasting before an insulin test? EVN follows the non-fasting consensus

Whether a horse should fast before an insulin test depends on the protocol chosen — different approaches exist. EVN follows the current specialist consensus not to fast: fasting can change insulin readings and mask a real problem. We take blood while the horse is on its normal forage. Always discuss the approach with the vet running the test.

Every extra 100 kg adds around 120 kg of force to the legs — with each stride

At trot, each front leg carries roughly 1.2 times the horse's bodyweight on every step. Trimming 100 kg of surplus weight takes about 120 kg of load off the limb with every single stride — which across one schooling session adds up to hundreds of tonnes of load the joints no longer have to absorb.

'Cushing's' is a misleading name for the horse's version of the disease

PPID (the condition often called equine Cushing's) is not really the same as Cushing's disease in people. Much of the hormone that is raised in PPID is a largely inactive form, which is why affected horses don't show the cortisol excess seen in true Cushing's. Interestingly, the underlying process is closer to a Parkinson's-type disease of the brain than to human Cushing's.

Fructan is not the driver of insulin-related laminitis

At grazing-realistic intakes, fructans are primarily a concern for hindgut acidosis. They do not drive the post-meal insulin response that underlies hyperinsulinaemia-associated laminitis — fructans are fermented in the hindgut rather than hydrolysed and absorbed in the small intestine. So for managing insulin-related laminitis, the focus is on sugar and starch, not fructan.

This is general information. It does not replace the individual feeding plan your EVN vet prepares for your horse after assessing it.