Putting weight on a skinny horse can be a difficult and frustrating task. There are many different causes of weight loss in horses and feeding strategies will require addressing the underlying cause of your horse’s poor body condition.

Weight loss occurs when a horse is in a negative energy balance, meaning that they are burning more calories per day than they are consuming.

Weight loss is especially common in senior horses who may be affected by multiple issues that contribute to reduced feed intake, poor digestion, and nutrient utilization.

Poor dental health, gastrointestinal issues, and low social standing can also contribute to weight loss.

When feeding to help a horse gain weight, many horse owners start with adding calories to the diet; however, it is important to first understand why your horse is losing weight and ensure they are healthy and in a comfortable environment.

It is also important to select the right energy sources to promote healthy weight gain without causing metabolic dysfunction.

Your veterinarian and equine nutritionist can help you get your horse to an ideal body condition.

Follow the steps in this article to develop a feeding plan to help your underweight horse gain weight. You can submit your horse’s information online and our nutritionists can help you design a diet to improve your horse’s body condition.

Is Your Horse Underweight?

How do you tell if your horse is underweight? Both body weight and body condition score (BCS) are important metrics to help decide if your horse needs to gain weight. Body condition scoring will help you determine what your horse’s ideal body weight is for their size and breed.

The Henneke Body Condition Scoring Scale evaluates a horse’s condition by looking at six specific points on the body and assessing fat deposition. Horses are considered underweight if they have a body condition of 4/9 or less. [1]

Underweight horses will be classified as one of the following:

  • BCS of 4 – slightly underweight (moderately thin)
  • BCS of 3 – underweight (thin)
  • BCS of 2 – very underweight (very thin)
  • BCS of 1 – poor (emaciated)

In underweight, very underweight, and emaciated horses, the neck, shoulders and withers are clearly accentuated, and the boney projections of the spine are visible to varying degrees.

Thin Underweight Body Condition Score Horse

We recommend conducting weight measurements and body condition scoring at least once per month as indicators of your horse’s nutritional and health status. Keep a log of these numbers to assess how your horse changes over time and to make adjustments in their diet as needed.

Body Condition Scoring for Horses

Causes of Weight Loss in Horses

Weight loss is not a disease in itself, but rather a symptom of a larger problem.

Weight loss or inability to gain weight effectively can be attributed to several factors including:

  • Dental issues
  • Social and behavioural issues
  • Musculoskeletal disorders
  • Temperature and environmental factors
  • GI parasites
  • Gastrointestinal disorders
  • Other underlying systemic diseases
  • Malnutrition (nsufficient nutrient intake)
  • Starvation (due to neglect or abuse)

If your horse has shown recent weight loss or is struggling to gain weight, consult with your veterinarian to identify any medical issues that need to be addressed.

Once you have ruled out medical concerns, our equine nutritionists can help formulate an appropriate diet plan to help your underweight horse gain weight in a healthy manner.

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How to Support Healthy Weight Gain

1) Identify and manage dental issues

Taking up food (prehension) and chewing (mastication) are the first steps in the digestive process that allows the horse to extract enough nutrients from its feed to support healthy body weight.

Horses rely on healthy teeth to grind and break down feed. Chewing increases the surface area of the food to initiate its digestion by enzymes. [3]

Dental issues are one of the most common reasons a horse may be losing weight. In a recent study by Tamzali and colleagues, 20% of underweight horses were diagnosed with dental problems. [2]

This primarily affects senior horses (over 15 years of age), of which up to 95% have dental abnormalities. [4]

Dental issues can range in severity, from sharp enamel points that cause discomfort when chewing to significant dental abnormalities or diseases that impair mastication.

Senior horses commonly lose teeth or develop gaps between their teeth, called diastemata, which can allow food to get stuck between the teeth and decompose. This can lead to pain, inflammation, and impair the normal mechanics of mastication.

More serious dental conditions such as equine odontoclastic tooth resorption and hypercementosis (EOTRH) can also arise with age and affect your horse’s ability to prehend feeds. [6]

Below are several steps you can take to support your horse’s dental health and help them chew comfortably and effectively. Frequent monitoring of eating behaviour and dental health is important to identify issues with chewing.

  • Monitor how your horse is eating: Look for quidding (dropping feed), food pocketing, overproduction of saliva, or reluctance to eat certain feeds
  • Have their teeth floated: Your horse should have a dental exam by a licensed veterinarian at least once per year. Your veterinarian may determine at this visit that a dental float is necessary to correct any abnormalities identified on exam
  • Monitor senior horses more closely: Horses over the age of 15 may need their teeth checked more frequently to keep an eye on common dental issues that arise with age
  • Soak their hay: For horses that struggle to eat forage, soaking or steaming their hay might be beneficial to soften the fibres
  • Replace their forage: For horses with advanced dental issues, alternatives like soaked hay cubes, beet pulp, hay extenders, soybean hulls and/or concentrate feeds may need to be fed in place of forages. In severe cases or for horses with no teeth left, these soaked mashed can make up 100% of the horse’s diet

2) Support gastrointestinal health

Proper function of the digestive system is critical for your horse’s overall health and for converting feed into usable forms of energy. When things go wrong in their digestive system, horses can lose weight quickly.

Gastrointestinal conditions such as stomach ulcers, inflammatory bowl disease, infiltrative bowel disease, or hindgut ulcers may be causing your horse to lose weight.

For horses prone to digestive issues, a forage-first diet with minimal concentrate feeds will support gastric health and decrease the risk of hindgut acidosis.

Limit starch intake to be below 1 gram per kg of bodyweight per meal (500 grams of starch for a 500 kg horse), or no more than 2 grams of starch per kg bodyweight per day (1000 grams starch for a 500 kg horse). [19]

Monitor your horse’s fecal consistency as a sign of potential digestive issues. Conditions such as free fecal water syndrome (FFWS) can be a sign of impaired digestive health.

Changes in fecal content may also be a sign of dental health issues that affect your horse’s ability to break down fibres. [5]

3) Combat Intestinal Parasites

Endoparasites, also known as intestinal worms, are another cause of weight loss in horses.

Parasites can be present with or without diarrhea and can negatively affect absorption of nutrients from the gut. Small strongyles (cyathostomins) are the most common type of parasitic infection in mature horses. [14]

Age does not appear to be a factor in parasitic risk but may influence the type of parasites your horse is likely to be affected by. Horses with Cushing’s / PPID appear to have higher parasite burdens. [15]

Resistance to dewormers (also referred to as anthelmintics) is a growing concern. Previous veterinary deworming protocols relied on a preventative, rotational deworming program that is ineffective against small strongyles. [14]

Fecal egg counts are strongly recommended to determine the parasite burden of your horse. [14] If the parasite burden is high, your veterinarian can identify the predominant species of parasite and prescribe an appropriate treatment.

Individualized, evidence-based deworming protocols are the way to go!