Pregnant and Prone to Laminitis: How to Feed a Sugar-Sensitive Mare

A pregnant mare who suddenly comes up stiff, hot in the feet, or unwilling to shift her weight: it's the phone call every breeder dreads. Laminitis mid-pregnancy isn't common, but it happens, and it happens more easily than owners think once a mare already carries some insulin dysregulation. When it does, the feed room is usually the first thing that needs to change.

Get her healthy before you breed her, if you can

Here's the plain answer, before anything else: you don't want to be dealing with this at all. A mare should ideally go into pregnancy at a stable weight, with her insulin response already under control, not figuring it out mid-gestation. Pregnancy and lactation are demanding enough on their own. Add a laminitis history on top, and feeding her stops being routine. It becomes a daily balancing act.

But she's already in foal, and now she's laminitic. What now?

This is the question we get more often than you'd think: my mare is pregnant and sugar sensitive, or she's had laminitis before, what do I do now? A bit of nuance helps here. You'd rather avoid this altogether, but if it's already the reality, it isn't a crisis you can't manage. It mostly means being more exact about what you feed, because a pregnant or lactating mare still needs her minerals, for herself and for the foal she's carrying.

What the research actually says

There's more science behind this than most feed-room conversations let on. A 2023 review in Frontiers in Veterinary Science looked specifically at obesity and insulin dysregulation in broodmares, and called laminitis "the gravest consequence" of insulin dysregulation in horses. Late pregnancy already brings a natural rise in insulin resistance, so a mare who's already insulin dysregulated stacks that physiological shift on top of an existing vulnerability, right when her feed volume tends to go up.

The same review found something worth sitting with: mares fed high-starch diets produced foals with higher baseline glucose, and some of those foals started showing signs of insulin resistance by around 160 days old, even when the mare herself wasn't overweight. So the sugar load isn't only a hoof problem for her. It can shape the foal's metabolism too.

Why a mare concentrate backfires here

Take a 500 kg mare on a typical mare concentrate. In late pregnancy, from around month nine, that can land at roughly 480 g of sugar and starch a day. Move into the first four months of lactation and the ration usually climbs, easily 750 g a day once you're feeding enough to cover her requirements. General guidance for laminitis-prone horses puts the ceiling at under 10% NSC on a dry matter basis for a high-risk horse, and horses with confirmed insulin dysregulation tolerate roughly ten times less sugar and starch per meal than a metabolically normal horse does. A concentrate works against that by design: to hit the mineral target, you need to feed a fairly large portion, and that portion drags all the starch along with it. For a mare who's sensitive to it, that's backwards.

What the balancer changes

A balancer flips the ratio. It's a concentrated vitamin and mineral base fed in a small daily amount, on top of forage, instead of a bulk feed dosed for calories. For a 500 kg mare that's 250 g a day, which works out to roughly 19 g of sugar and starch, a fraction of what a concentrate requires, while still delivering the full 120 mg of copper and 600 mg of zinc she needs.

That copper number matters more than it looks. A 1998 study in the Equine Veterinary Journal supplemented pregnant Thoroughbred mares with copper and found it significantly reduced physitis and cartilage lesions in their foals at 150 days old. Supplementing the foal directly, after birth, did nothing. The window that counts is the mare, during pregnancy, which is exactly why this isn't a nice-to-have you can skip if she seems fine.

The month-by-month plan

For a 500 kg mare, in practice:

• Full pregnancy: forage plus 250 g balancer a day, moving to roughly 300 g from month 7.
• Lactation, month 1: 300 g balancer, plus 300 to 500 g of Este Power.
• Lactation, months 2 to 4: 300 g balancer, plus 500 to 1,000 g of Este Power, with months 2 and 3 as the peak.
• From month 5: taper the Este Power back off, and bring the balancer back down to 250 g.

That extra protein is only worth adding if she's losing condition. If she's holding her weight well, or on the heavier side, you can often stay on the balancer alone.

Extra energy for lactation, without the sugar

Lactation is the one phase where a laminitis-prone mare often does need more calories, not just minerals. That's where an oil-based supplement earns its place instead of a starchy feed: it adds condition and coat quality without the insulin spike a grain-based energy source brings.

Getting a mare pregnant once she's already in good shape stays the better order of operations. When reality runs differently, the feed is the first thing you adjust, not the last.