Hard Doers - Safe Weight Gain for Underweight Horses
- Dec 12
- 4 min read
Hard doers (or “hard keepers”) are horses that struggle to maintain weight and condition, requiring careful feeding strategies focused on calorie density, digestive health, and balanced minerals. They tend to be thoroughbreds, senior horses and performance horses.
Here is a before-and-after of a rescue mare on a Sound Advice diet:
What is underweight?
A horse’s weight is usually measured using the body condition score:
BCS 1–3: Underweight
BCS 1: Emaciated — no fat cover, prominent bones
BCS 2–3: Thin — ribs and spine visible, poor muscle mass
BCS 4–6: Ideal range for most horses
BCS 4: Lean but healthy
BCS 5–6: Moderate fat cover, good muscle tone — ideal for performance and general health
BCS 7–9: Overweight to obese
BCS 7: Fleshy — fat deposits visible
BCS 8–9: Obese — high risk for metabolic disorder
Visible ribs are not the ideal measure of healthy weight, since many senior horses, broodmares and even young, fit horses that have good muscle tone may have some ribs visible. Thigh gap is a much better indicator. A horse that can have ribs showing for various reasons can also have no thigh gap.
This is important because adding unnecessary weight to a horse in moderate condition can cause:
Insulin resistance and equine metabolic syndrome (EMS)
Excess fat, especially in the neck and tailhead, disrupts insulin regulation.
Laminitis
Overweight horses are at higher risk for painful hoof inflammation, especially if fed high-sugar feeds
Reduced athletic performance
Extra weight strains joints, reduces stamina, and increases injury risk
Poor fertility and hormonal imbalance
Heat stress and respiratory strain
Fat horses struggle more in hot weather and during exercise
When Weight Gain Is Appropriate
Horses with BCS < 4 due to age, illness, poor dentition, or high workload
Horses recovering from neglect or chronic disease
Key Principles for Feeding a Hard Doers
Rule out underlying issues first.
Weight loss can stem from:
Always address these before adjusting feed.
Hay. Then more hay
Prioritise forage quality and quantity
Even on 24/7 turnout, provide free-choice, high-quality forage (lucerne hay, or grassy lucerne).
Forage should form the bulk of the diet to support gut health and reduce ulcer risk.
Add calorie-dense feeds safely
While it’s tempting to add a whole lot of sweet feed, these can cause other problems down the track.
Avoid:
Grain-heavy diets, which increase ulcer and colic risk.
Any feeds bound with molasses
Any feeds with corn or maize. These are high in starch and when fed in volume, can cause hind gut acidosis
White chaffs are low in nutritional value and can be 20% sugar or higher. We don't recommend white chaffs for any horse.
Instead, use high fat and fibre-based feeds These provide slow-release energy and are easier on the digestive system. They also have other qualities that contribute to overall health.
Beet pulp is high in calcium and helps with hydration, it is easy to eat for horses with poor dentition and is a good carrier for supplements.
Soybean hulls are high fibre and low GI, and form a mash.
Copra meal is high in fats and highly palatable for fussy eaters
Rice bran is a good source of phosphorous to balance your calcium:phosphorous ratio for bone health.
Linseed meal supplies dense calories and is a great source of omega 3s which are anti-inflammatory.
Ensure adequate protein for muscle maintenance
Lucerne is high in calcium and protein, and low in sugar
Soybean meal is a good source of amino acids.
What Makes These Ingredients Effective?
Feeds higher in fat provide 2.25x more energy than carbohydrates, making it a safer way to increase calories.
Fibre supports gut health and slow energy release, reducing digestive stress.
Protein helps build topline and maintain muscle mass, especially in working or older horses
Supplying optimal minerals not only assists with weight maintenance, but health overall.
Macro minerals calcium and phosphorous can generally be supplied in feeds. Trace minerals are generally deficient in feeds - you can supplement them efficiently and affordably with our Sound Advice Trace Mixes.
How Mineral Deficiencies Affect Body Condition
Direct impacts on weight and condition:
Zinc & Copper Deficiencies can lead to poor appetite, dull coat, weak hooves, and slow wound healing.
Selenium & Vitamin E Affect muscle function and recovery; deficiency may cause muscle wasting or weakness.
Calcium & Phosphorus Imbalances impair bone development and may reduce feed efficiency.
Magnesium Deficiency can cause nervousness, poor feed conversion, and reduced weight gain.
Indirect effects:
Reduced feed efficiency. Even with adequate calories, a horse may fail to gain weight if minerals needed for digestion and metabolism are lacking.
Compromised immune function. Chronic infections or inflammation can suppress appetite and increase energy demands.
Hormonal disruption. Trace minerals like iodine and selenium are essential for thyroid and metabolic regulation.
Key Takeaways
While it's tempting to increase weight rapidly with high sugar, empty calories, this can cause a range of other problems in the long-term.
For overall health over time you are looking to supply dense calories that contribute other properties to the whole diet.
It is normal for a young fit horse, or a performance horse to be lean. Trying to make a young horse overweight can compromise metabolic function in the future.
Trace minerals are generally deficient in horse diets, which has an influence not just on weight but many other functions in the body. Our Trace Minerals mixes cover micronutrient gaps.
Salt should be available, especially for performance horses.
Support digestive health with yeast/probiotic supplements to improve fibre digestion.
Monitor progress
We always encourage horse owners to take frequent photos of their horses, and to record any changes in feed. That way you can correlate when horses are prospering and what their diet was at that time.
Track body condition score (BCS) and weight regularly. If your horse is rugged, take the rug off regularly and check your horse's condition. Frequent grooming gives you an opportunity to examine your horse's skin and detect small problems before they become big ones.
Adjust feed gradually to avoid digestive upset.
Every horse is different. We are here to help! Get in touch at info@soundadvice.shop
Comments