Sugar: balance is key to your horse's health
Short version: see the overview
For a good doer, we recommend approx. 0.5-1 g of sugar per kg of body weight per day as a practical precautionary level, not as a fixed clinical limit. Above 2 g per kg of body weight per day causes disease.
Measured in the forage: a good doer should be below 5-7 % sugar in the dry matter. Horses in regular work, where they get out of breath and sweat, can tolerate up to 10 %.
How much sugar can the horse tolerate
The limit is calculated on the horse's own weight. A good doer weighing 400 kg is therefore best kept at 200-400 g of sugar a day, and above 800 g causes disease.
| Horse's weight | Tolerates per day (0.5-1 g per kg) | Causes disease above (2 g per kg) |
|---|---|---|
| 300 kg | 150-300 g | 600 g |
| 400 kg | 200-400 g | 800 g |
| 500 kg | 250-500 g | 1,000 g |
| 600 kg | 300-600 g | 1,200 g |
The sugar comes mainly from grass, haylage and hay. Treats, apples and carrots count towards the total.
Don't know your horse's weight?
Measure the circumference around the belly at the girth line with a measuring tape while the horse stands square on all four legs. The formula is the girth measurement in metres, cubed, multiplied by 80.
392 kg is an informed estimate of the weight and good enough to work out the sugar limit.
The limit in the forage
The other way to keep an eye on sugar is the percentage in the forage's dry matter. You'll find it in a forage analysis, and it should be adjusted to the horse's workload.
| Type of horse | Sugar in dry matter |
|---|---|
| Good doers and ponies | Below 5-7 % |
| Horses in regular work that get out of breath and sweat | Up to 10 % |
The less work the horse does, the tighter you need to keep the sugar. Sugar that isn't used as energy ends up as imbalance.
Work out the sugar in your own forage
A forage analysis shows the sugar percentage in your hay or haylage, and it is given on a dry matter basis. From there it's simple maths in three steps.
- Step 1: Amount of forage per day multiplied by the dry matter percentage gives kilos of dry matter.
- Step 2: Kilos of dry matter multiplied by the sugar percentage gives kilos of sugar.
- Step 3: Multiply by 1,000 and you have grams of sugar per day.
Example: 7 kg haylage with 75 % dry matter
Same amount of haylage, same horse, two very different results. It's the analysis that tells you which of the two you have.
| Scenario | Sugar per day | For a 400 kg good doer | Assessment |
|---|---|---|---|
| 7 kg haylage, 17 % sugar | 892 g | 2.2 g per kg body weight | Far too much, above the 2 g per kg that causes disease |
| 7 kg haylage, 7 % sugar | 368 g | 0.9 g per kg body weight | Within the precautionary level of 0.5-1 g |
How do you know if your horse is getting too much
Get a forage analysis done. It shows the sugar percentage in your hay or haylage, so you can work out whether the forage is within the limit or whether the horse is getting too much. The analysis only applies to the batch you have in store, so you need a new one with every new load.
Without an analysis, you're left guessing. If the horse is a good doer or on the round side, the safest starting point is to assume the sugar is too high.
Signs your horse may be getting too much sugar
- Laminitis or a tendency towards sore feet
- Excess weight and fat deposits, e.g. on the neck or tail head
- Metabolic problems such as EMS or PPID
- Unsettled gut and poor digestion
- High insulin, or low energy despite plenty of feed
Adjust sugar intake to your horse's workload
- Keep good doers below 5-7 % sugar in dry matter
- Horses in regular work that get out of breath and sweat can go up to 10 %
- Mix straw into the forage so the total sugar content drops without reducing chewing time
- Limit time on grass, especially in spring and autumn and after cold nights
- Use a grazing muzzle or short turnout when needed
- Watch out for treats, apples and carrots. Small amounts are fine, but they quickly add up
Too much sugar can cause serious problems, and the only way to know how much your horse is really getting is to know the sugar content of the forage.
Related articles on sugar and metabolic health
- How much sugar can a good doer tolerate?
- What happens when a horse gets too much sugar?
- How much sugar does your horse get from grass?
- Sugar, fructan, laminitis and lifestyle diseases: what do we actually know?
- Cresty neck in horses: the most important warning sign worth learning to spot
