How To Put Weight on a Skinny Horse Safely

How To Put Weight on a Skinny Horse Safely

By Dr Duncan Houston

A skinny horse can make any owner feel worried, guilty, or completely overwhelmed.

The natural instinct is to feed more. More hay, more grain, more oil, more supplements, more of anything that might fill the ribs in. But weight loss in horses is not always a simple calorie problem.

Sometimes the horse is not getting enough feed. Sometimes the hay is poor. Sometimes another horse is pushing them away. Sometimes the teeth are failing. Sometimes parasites, ulcers, PPID, chronic pain, infection, liver disease, kidney disease, or poor absorption are quietly sitting underneath the problem.

The safest way to help a thin horse gain weight is not to throw calories at them blindly. It is to work out why they are thin, then build the diet carefully around forage, digestible fibre, safe calories, good protein, clean water, dental care, parasite control, and regular monitoring.

Quick Answer

To put weight on a skinny horse safely, first rule out medical causes such as dental disease, parasites, gastric ulcers, PPID, chronic pain, poor feed access, and systemic illness. If the horse is otherwise healthy, weight gain should be slow and controlled, usually by improving forage quality, increasing total intake gradually, adding digestible fibre and fat, and keeping grain meals small. Merck Veterinary Manual notes that a weight-gain diet for a generally healthy horse may aim for about 2% to 2.5% body weight in total dry matter intake, with body weight monitored every 1 to 2 weeks and weight gain expected over weeks to months rather than days. (Merck Veterinary Manual)

If the horse is severely emaciated, weak, not eating, colicky, diarrhoeic, febrile, footsore, or rapidly losing weight, this needs veterinary attention before major feed changes. Rapid refeeding of starved horses can cause potentially fatal refeeding syndrome. (Merck Veterinary Manual)

First: Is the Horse Thin or Losing Muscle?

Not every “skinny” horse has the same problem.

Some horses are truly underweight, with poor fat cover over the ribs, spine, hips, and tailhead. Others have muscle loss, especially over the topline, but still carry fat elsewhere. This is common in older horses, horses with PPID, horses out of work, and horses with chronic pain.

That distinction matters.

A horse with poor fat cover usually needs more usable calories after disease is ruled out. A horse with topline loss may need better protein quality, correct amino acids, exercise if sound, pain management, or endocrine testing, not just more calories.

A pot-bellied senior with a poor topline is not necessarily “well covered.” They may be losing muscle while still having a round abdomen. That is a classic trap.

How To Body Condition Score a Thin Horse

Use body condition scoring rather than guessing from across the paddock.

The common Henneke system scores horses from 1 to 9, where 1 is extremely emaciated and 9 is extremely obese. Oklahoma State University describes body condition scoring as an assessment of visible and palpable fat cover, with the low scores showing obvious ribs, spine, pelvic bones, and lack of fat cover. (extension.okstate.edu)

Check these areas with your eyes and hands:

• Neck

• Withers

• Behind the shoulder

• Ribs

• Back or loin

• Tailhead

• Hip bones and pin bones

For many horses, a body condition score around 5 out of 9 is a useful target. Performance horses may sit slightly lower depending on discipline, but most leisure horses, seniors, broodmares, and recovering horses should not be allowed to drift into obvious rib, spine, and hip prominence without investigation.

A very thin horse needs a plan. An emaciated horse needs a vet.

Why Is My Horse Skinny?

There are many reasons a horse may be thin. The most important ones are not always feed-related.

Not Enough Calories

This is the obvious one.

The horse may simply not be eating enough digestible energy to match their needs. This can happen with poor hay, limited pasture, cold weather, heavy work, lactation, stress, travel, or being fed by scoops and flakes rather than weighed amounts.

Horses needing weight gain often need better forage, more total intake, more digestible fibre, or a higher calorie feed. University of Minnesota Extension recommends giving underweight horses as much forage as possible, improving hay quality where needed, and using higher fat or performance feeds when forage alone is not enough. (University of Minnesota Extension)

Poor Teeth

Dental disease is one of the biggest causes of weight loss, especially in senior horses.

A horse may stand at the hay and appear to eat, but if they cannot chew properly, they may not be breaking down forage enough to digest it. AAEP lists dental warning signs such as loss of feed from the mouth, difficulty chewing, excessive salivation, loss of body condition, long stems or whole grain in manure, foul odour, nasal discharge, and swelling of the face or jaw.

In practice, this is one of the first things I would check in a thin horse. You cannot feed your way around a painful mouth forever.

Parasites

Parasites can contribute to poor condition, poor coat, diarrhoea, colic risk, and reduced nutrient use. But modern parasite control should not just mean “worm everything every two months.”

AAEP recommends fecal egg count reduction testing annually to check dewormer effectiveness, fecal egg counts once or twice yearly to identify low, medium, and high shedders, baseline deworming once or twice yearly, and targeted treatment based on fecal egg counts rather than blind rotation. (AAEP)

A thin horse needs a parasite review, but do not assume one random dewormer will solve a chronic weight problem.

Gastric Ulcers

Gastric ulcers can cause vague signs in adult horses, including poor appetite, mild weight loss, poor body condition, attitude changes, and colic-like discomfort. Merck Veterinary Manual notes that signs are often subtle, and that endoscopy is the only reliable diagnostic method. (Merck Veterinary Manual)

If a horse is picky, girthy, sour, underperforming, losing weight, or uncomfortable around feeding or work, ulcers should be on the list.

PPID or Cushing’s Disease

PPID is common in older horses and can cause muscle loss, poor immune function, delayed shedding, long curly hair coat, lethargy, abnormal sweating, increased drinking and urination, and laminitis. UC Davis notes that PPID often causes loss of muscle, especially along the topline, and that about 30% of horses with PPID also show insulin dysregulation. (Center for Equine Health)

That matters because a PPID horse may be thin, but still laminitis-prone. Feeding that horse high-starch weight-gain feeds without checking insulin status can be a very expensive hoof mistake.

Poor Feed Access

Some horses lose weight because they are not actually eating what owners think they are eating.

Common reasons include:

• Another horse pushing them away

• Too few feeding stations

• Slow eating due to dental disease

• Pain making it hard to walk to hay or water

• Anxiety in a herd

• Feed being stolen

• Poor water access

• Hay placed too far from shelter or water

• Old horses needing rest breaks while eating

University of Minnesota notes that horses low in the pecking order may not get adequate access to hay, feed, and water, and that poor water intake can also reduce feed intake. (University of Minnesota Extension)

Before increasing the ration, make sure the horse actually gets to eat it.

Chronic Disease or Pain

Weight loss can also come from chronic pain, infection, liver disease, kidney disease, cancer, malabsorption, respiratory disease, diarrhoea, inflammatory bowel disease, lameness, poor recovery from illness, or chronic stress.

Rutgers notes that if an older horse fails to maintain weight despite good deworming, normal appetite, and adequate rations, teeth should be checked carefully, and if teeth are normal the horse should have a veterinary exam and bloodwork to check for chronic infections and liver or kidney dysfunction. (Equine Science Center)

Old age is not a diagnosis. It is a reason to investigate sooner.

Risk Framework: How Worried Should You Be?

Low Risk

This is usually lower risk if your horse:

• Is mildly underweight

• Is bright and eating normally

• Has normal manure

• Has no colic signs

• Has no diarrhoea

• Has no fever

• Has no sudden change in weight

• Has no laminitis signs

• Has good dental function

• Has a clear reason for weight loss, such as increased work or poorer hay

This horse still needs a structured plan, but it may not be an emergency.

Moderate Risk

This is more concerning if your horse:

• Has a body condition score around 3 out of 9

• Has visible ribs and reduced topline

• Is losing weight over several weeks

• Eats slowly or drops feed

• Has inconsistent manure

• Is a senior

• Has poor coat quality

• Has recent stress, travel, or illness

• Is being bullied off feed

• Has not had recent dental care or parasite review

This horse needs a veterinary and nutrition review. Do not just keep increasing grain.

High Risk

This is high risk if your horse:

• Has a body condition score of 1 to 2 out of 9

• Is rapidly losing weight

• Is weak, dull, or reluctant to move

• Has diarrhoea

• Has fever

• Has recurrent colic

• Has choke signs

• Has severe dental disease

• Has PPID signs

• Has poor appetite

• Has unexplained muscle wasting

• Is pregnant, lactating, growing, or very old

• Is thin but also footsore or laminitis-prone

This horse needs veterinary assessment before a major feeding change.

Critical

This is urgent if your horse:

• Is not eating

• Is unable to chew or swallow

• Has feed or saliva coming from the nose

• Has colic signs

• Has severe diarrhoea

• Has fever and depression

• Is recumbent or too weak to stand normally

• Is severely dehydrated

• Has sudden laminitis signs

• Is emaciated after neglect or prolonged starvation

• Is rapidly deteriorating

This is not a “try a new feed” situation. Call a vet.

When Is Weight Loss an Emergency?

Call a vet urgently if your horse has:

• Repeated lying down, rolling, pawing, flank-watching, or sweating

• Feed or saliva coming from the nostrils

• Difficulty chewing or swallowing

• Complete loss of appetite

• Severe diarrhoea

• Fever

• Depression or weakness

• Rapid weight loss over days

• Severe dehydration

• Heat in the feet

• Strong digital pulses

• A pottery gait or rocked-back stance

• Collapse or recumbency

• Severe emaciation

A severely thin horse should not be aggressively fed without veterinary guidance. Merck warns that rapid introduction of food in starved horses can cause potentially fatal refeeding syndrome. (Merck Veterinary Manual)

The cruel irony is that feeding too much too quickly can harm the horse you are trying to save.

What Should a Vet Check in a Skinny Horse?

A proper work-up depends on the horse, but common steps include:

• Full physical examination

• Body condition score

• Actual weight or weight estimate

• Dental examination with speculum

• Diet history with feed weights

• Hay or forage analysis

• Fecal egg count and parasite plan

• Bloodwork to check inflammation, anaemia, liver, kidney, protein, and metabolic status

• ACTH testing for PPID in older horses

• Insulin testing if laminitis risk, cresty neck, or PPID is present

• Gastroscopy if ulcers are suspected

• Manure, diarrhoea, or malabsorption investigation if indicated

• Pain and lameness assessment

• Herd access and management review

The diet is only one part of the case. The skinny horse standing in front of you may be telling you about teeth, gut, hormones, parasites, pain, or social stress.

What Should You Do Next?

1. Weigh the Horse or Estimate Weight

A scale is best. A weight tape or body weight equation is still useful for tracking trends.

Merck notes that body weight should be monitored frequently during weight gain, ideally every 1 to 2 weeks, and the diet should be adjusted based on response. (Merck Veterinary Manual)

Do not rely on memory. Take photos from the side, front, and behind every 2 weeks. Same location. Same angle. Same lighting. Less artistic, more useful.

2. Body Condition Score Every 2 Weeks

Track body condition, not just belly size.

A horse may gain gut fill before gaining true body condition. That means the horse can look rounder quickly but not actually have rebuilt fat and muscle yet.

Useful tracking points:

• Ribs

• Spine

• Tailhead

• Hip bones

• Neck

• Withers

• Shoulder

• Topline

• Coat quality

• Appetite

• Manure

• Energy

If nothing improves after 3 to 4 weeks of a sensible plan, reassess the diagnosis.

3. Start With Forage

Forage should be the foundation of almost every weight-gain plan.

For a thin but otherwise healthy horse, this may mean:

• More hay

• Better quality hay

• More pasture if safe

• Adding alfalfa or lucerne strategically

• Using soaked hay cubes

• Using soaked hay pellets

• Using beet pulp

• Using a complete feed if the horse cannot chew hay

University of Minnesota recommends giving underweight horses 24-hour access to pasture or hay where possible, and if more hay is not enough, improving hay quality with options such as alfalfa or immature grass hay. (University of Minnesota Extension)

This is the boring answer, and it is usually the right place to start.

4. Increase Calories Gradually

For a generally healthy underweight horse, Merck suggests slowly increasing caloric intake by around 15% to 25% and aiming for weight gain over at least 30 to 90 days, depending on the horse and the amount of weight needed. (Merck Veterinary Manual)

Do not double the feed overnight.

Sudden feed changes can upset the hindgut and increase the risk of diarrhoea, colic, laminitis, and feed refusal. University of Minnesota recommends making feed changes gradually over a two-week period. (University of Minnesota Extension)

5. Use Digestible Fibre

Digestible fibre is one of the safest ways to add calories.

Good options may include:

• Beet pulp without molasses

• Soy hull-based feeds

• Alfalfa pellets

• Hay cubes

• High-fibre complete feeds

• Senior feeds when appropriate

Digestible fibre is especially useful when hay quality is poor, teeth are not perfect, or the horse needs more calories without large starch-heavy meals.

Soak beet pulp, hay cubes, and pellets where needed, especially in horses with dental issues, choke history, or poor water intake.

6. Add Fat Carefully

Fat is calorie dense and can help add weight without adding large amounts of starch.

Options include:

• Vegetable oil

• Stabilised rice bran

• Flax

• Higher-fat commercial feeds

• Fat supplements designed for horses

Merck notes that oils and fats can be added to increase energy density, but they should be introduced slowly, and horses may need 3 to 4 weeks to fully adapt to a higher-fat diet. (Merck Veterinary Manual)

University of Minnesota also warns that introducing a high-fat diet too quickly can cause greasy faeces or diarrhoea. (University of Minnesota Extension)

Start small. Increase slowly. Monitor manure. The hindgut does not appreciate surprise oil slicks.

7. Be Careful With Grain

Grain can help some thin horses, but it is not always the safest first move.

Large starch-heavy meals can increase the risk of digestive upset, colic, laminitis, and behavioural changes in some horses. Merck states that horses should not receive more than 0.5% of body weight in grain-based concentrates in a single meal. For a 500 kg horse, that is 2.5 kg in one feeding, and many horses should receive much less. (Merck Veterinary Manual)

If grain or concentrate is needed:

• Weigh it

• Split it into smaller meals

• Avoid sudden increases

• Choose the right feed for the horse

• Avoid high-starch feeds in laminitis-prone or insulin-dysregulated horses

• Do not feed large meals before strenuous work, transport, or stress

A bigger scoop is not a nutrition plan. It is often how colic stories begin.

8. Do Not Forget Protein

Calories add weight, but protein quality helps rebuild muscle.

Protein matters especially for:

• Poor topline

• Seniors

• Growing horses

• Lactating mares

• Horses recovering from illness

• Horses in work

• Horses on poor hay

Merck notes that protein quality and amino acids such as lysine, methionine, and threonine are important, and that alfalfa and legumes generally have a better amino acid balance than cereal grains or many grass hays. (Merck Veterinary Manual)

A horse with poor topline may not need more sweet feed. They may need better forage, higher quality protein, correct amino acids, soundness work, and disease control.

9. Protect Water Intake

Water intake affects appetite, gut function, and impaction risk.

University of Minnesota notes that poor water intake can slow feed intake, and that an average adult idle horse in a mild climate may drink about 10 gallons daily. (University of Minnesota Extension)

For skinny horses, check:

• Is the water clean?

• Is it close enough?

• Is it frozen, hot, dirty, or hard to access?

• Is another horse blocking the trough?

• Is the horse drinking normally?

• Is manure dry?

A horse cannot gain weight well if it is not drinking well.

10. Reduce Energy Waste

Sometimes putting weight on a horse means helping them conserve energy.

Consider:

• Shelter from wind and rain

• Rugging or blanketing where appropriate

• Pain control under veterinary guidance

• Reducing unnecessary hard work temporarily

• Lower-stress herd setup

• Feeding separately

• Extra meals in cold weather

• Ensuring older horses are not pushed off feed

Merck notes that in cold climates, clean dry shelter, forage, and appropriate rugging or blanketing can help conserve energy needed to maintain body temperature. (Merck Veterinary Manual)

A thin horse standing cold, wet, bullied, and sore is not going to gain weight just because the feed bucket got more ambitious.

A Practical Weight-Gain Plan for a 500 kg Horse

This is a general structure for a mildly to moderately thin adult horse that is bright, eating, not colicky, not diarrhoeic, not laminitic, and has had medical issues considered.

It is not for severely starved horses.

Step 1: Set a Baseline

Record:

• Current weight or estimate

• Body condition score

• Photos

• Dental status

• Fecal egg count plan

• Current hay weight

• Current concentrate weight

• Pasture access

• Water intake

• Manure quality

• Workload

Step 2: Improve Forage First

Aim for a forage-based diet.

For many healthy horses needing weight gain, total dry matter intake may sit around 2% to 2.5% of body weight per day, including forage plus any concentrates. For a 500 kg horse, that means roughly 10 to 12.5 kg of total dry matter daily as a broad starting range. (Merck Veterinary Manual)

Use the best forage the horse can safely handle.

Step 3: Add Digestible Fibre

If hay alone is not enough, consider soaked beet pulp, soaked hay cubes, alfalfa pellets, or a complete feed.

This is often safer than jumping straight to large grain meals.

Step 4: Add Fat Slowly

If more calories are needed, add fat gradually.

Introduce oil, rice bran, or a higher-fat feed slowly over several weeks. Monitor manure and appetite.

Be careful with rice bran in insulin-dysregulated horses, as Merck notes that rice bran is not necessarily low-starch or low-sugar and should be used cautiously in those horses. (Merck Veterinary Manual)

Step 5: Use Grain Only When Needed

If the horse still needs more calories, use a suitable concentrate and keep meals small.

Do not exceed safe concentrate meal sizes. Split into multiple meals when needed. (Merck Veterinary Manual)

Step 6: Recheck Every 1 to 2 Weeks

Adjust the diet based on:

• Weight trend

• Body condition

• Manure

• Appetite

• Energy

• Hoof comfort

• Behaviour

• Water intake

If the horse is not improving, do not just keep adding feed. Recheck the diagnosis.

Special Case: The Severely Emaciated Horse

A severely emaciated horse is different from a thin but stable horse.

If the horse has a body condition score of 1 to 2 out of 9, has been neglected, has had prolonged starvation, is weak, or has not been eating normally, they need veterinary-guided refeeding.

Oklahoma State University explains that refeeding poorly conditioned horses can be difficult even with supervision, and that veterinary intervention is necessary before and during refeeding because the plan must match the horse’s health status. (extension.okstate.edu)

Early refeeding usually focuses on small, frequent amounts of high-quality forage, often alfalfa or good hay, with careful monitoring. Grain and high-starch feeds are not the first move.

This is where kindness can accidentally become dangerous. Do not let sympathy drive the feed scoop.

Special Case: Senior Horses

Senior horses often lose weight because of teeth, PPID, chronic pain, poor absorption, or being outcompeted.

Rutgers notes that the most common causes of weight loss in aged horses include poor dentition, failure to maintain deworming schedules, and debilitating disease, and that a full mouth speculum exam is needed because simply pulling the tongue aside is not reliable for checking back teeth. (Equine Science Center)

Senior horses may need:

• Dental treatment

• Soaked hay cubes

• Soaked hay pellets

• Complete senior feed

• Smaller meals

• More time to eat

• Separate feeding

• PPID testing

• Bloodwork

• Pain management

• Shelter and temperature support

If an older horse cannot chew hay, the answer is not “more hay.” It is a different form of fibre.

Special Case: Thin But Laminitis-Prone Horses

Some horses are thin in one place and metabolically risky in another.

A PPID horse may lose topline but still have fat pads, a cresty neck, and insulin dysregulation. MSU notes that horses with PPID can appear thin while developing abnormal fat deposits, and insulin dysregulation increases laminitis risk. (Vet Med MSU)

These horses need calories without triggering insulin spikes.

Safer options may include:

• Tested low-NSC forage

• Soaked hay if appropriate

• Beet pulp without molasses

• Low-starch complete feed

• Oil introduced slowly

• Higher fibre, higher fat feeds

• Careful insulin and ACTH testing

• Avoidance of sweet feeds and high-starch grains

This is a vet and nutritionist conversation. Thin does not automatically mean grain is safe.

Common Mistakes Owners Make

Adding Too Much Grain Too Fast

This is the classic mistake.

Grain can add calories, but large starch-heavy meals increase digestive risk. Use forage, digestible fibre, and fat first where appropriate.

Ignoring Dental Disease

If the horse cannot chew, the feed plan fails before it reaches the stomach.

Not Weighing Hay

“Two flakes” means nothing. Hay flakes vary enormously.

Treating Old Age as the Diagnosis

Older horses do lose condition more easily, but weight loss can still be caused by treatable disease.

Overloading Supplements

Most thin horses do not need six miracle powders. They need diagnosis, enough calories, good protein, clean forage, water, dental care, and a balanced ration.

Forgetting Herd Dynamics

A horse may be “fed” but still not actually eating enough if another horse is stealing their food.

Rushing a Starved Horse

Severely emaciated horses must be re-fed slowly and under veterinary supervision.

How To Prevent Weight Loss in Horses

Prevention is easier than rebuilding a thin horse.

Do this:

• Body condition score every 2 to 4 weeks

• Track weight with a scale, tape, or measurements

• Photograph the horse regularly

• Weigh hay and feed

• Test hay when feeding long-term

• Keep dental exams current

• Use fecal egg counts and strategic parasite control

• Monitor older horses for PPID signs

• Watch manure, water intake, and appetite

• Separate slow eaters or low-ranking horses

• Provide shelter in bad weather

• Adjust calories before winter or heavy work

• Do not make sudden feed changes

• Investigate weight loss early

A horse should not have to become very thin before anyone takes action.

Will My Horse Be Okay?

Many skinny horses do very well once the real cause is found and the feeding plan is corrected.

A mildly thin horse with poor hay may improve with better forage, increased intake, and a gradual calorie boost. A senior with poor teeth may improve dramatically once the diet is changed to soaked forage and complete feed. A horse with PPID, ulcers, parasites, or chronic pain may only improve once the underlying condition is treated.

The prognosis is more guarded when the horse is severely emaciated, has chronic disease, ongoing diarrhoea, poor appetite, severe dental disease, laminitis, or has been starved for a long time.

The earlier you act, the easier it is.

Weight gain in horses is not a weekend project. It is usually a 30 to 90 day process for moderate gain, and severely thin horses may take months. (Merck Veterinary Manual)

FAQs

What is the fastest way to put weight on a horse?

The safest way is not always the fastest. First rule out medical causes, then increase calories gradually with better forage, digestible fibre, fat, and appropriate concentrates if needed. Rapid feeding changes can cause colic, diarrhoea, laminitis, or refeeding problems.

Should I feed more grain to a skinny horse?

Not automatically. Grain can help some horses, but large grain meals can increase digestive and laminitis risk. Improve forage first, then consider digestible fibre and fat before relying on high-starch feeds.

Is beet pulp good for weight gain in horses?

Beet pulp can be useful because it provides digestible fibre and can add calories without being a traditional grain. It should be soaked where appropriate, introduced gradually, and balanced with the rest of the diet.

Why is my horse eating but still losing weight?

Common reasons include dental disease, parasites, ulcers, PPID, poor forage quality, poor absorption, chronic pain, feed competition, liver or kidney disease, or not actually eating enough by weight. A veterinary work-up is needed if weight loss continues despite an apparently adequate diet.

How long does it take a skinny horse to gain weight?

For a generally healthy underweight horse, visible improvement usually takes weeks. Merck notes that gaining about 50 lb may take 30 to 90 days, depending on the individual horse and the amount of weight needed. Severely emaciated horses may take several months and need veterinary-guided refeeding. (Merck Veterinary Manual)

Final Thoughts

Putting weight on a skinny horse is not just about feeding more.

It is about finding the reason the horse is thin, correcting the foundation, and increasing calories in a way the gut, feet, metabolism, and teeth can handle.

Start with the horse, not the feed bag.

Check the teeth. Review parasites. Consider ulcers, PPID, pain, chronic disease, herd dynamics, forage quality, water intake, and weather stress. Then build the diet around high-quality forage, digestible fibre, safe fats, good protein, weighed meals, and steady monitoring.

A skinny horse does not need panic feeding.

They need a plan.

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If you are unsure why your horse is losing weight, whether they need dental care, bloodwork, parasite testing, ulcer investigation, or a safer feeding plan, ASK A VET™ can help you work through the signs and decide what needs attention before a weight problem becomes a crisis.