Does your horse appear bloated with an enlarged belly? Bloating in horses is a serious concern, as it can be an early indicator of colic, a potentially life-threatening condition.

Bloating can stem from multiple underlying causes, including digestive disturbances and intestinal blockages such as enteroliths. In many cases, bloating is a result of gas accumulation in the gut, causing abdominal distension and discomfort.

In addition to a rounded abdomen, affected horses may show other clinical signs such as reduced appetite, pawing or looking at the flank, or an increased heart rate. Signs can present suddenly and severely, or have a more gradual onset. [1][2]

If you suspect your horse is bloated, contact your veterinarian to investigate and treat any underlying conditions. Proper management, light movement, dietary adjustments including changes in forage intake, and medication may be required to resolve bloating in your horse. [3]

Bloating in Horses

Bloating in your horse can result from various factors, often related to dietary issues or changes in feeding patterns. Understanding the reason why your horse appears bloated is crucial for effective management and timely intervention.

Veterinarians use the Seven F’s to identify and categorize potential sources of abdominal bloating in horses: [2]

  • Fat: Excessive fat accumulation in the abdominal region
  • Fluid: Abnormal fluid accumulation within the abdominal cavity, such as ascites
  • Food: Dietary issues including excessive consumption of concentrates, low-quality forage, or abrupt changes in diet
  • Feces: Impaction of fecal matter within the intestines or colon causing abdominal distension
  • Fetus: In pregnant mares, growth of the fetus contributing to abdominal enlargement
  • Flatus: Excessive gas production or retention within the digestive tract
  • Foreign Body: Ingestion of foreign objects (i.e. sand) that become lodged within the gastrointestinal tract, obstructing normal digestive processes

Your veterinarian will conduct a physical exam and ask you about other changes observed in your horse to diagnose the underlying cause of your horse’s abdominal bloating.

Clinical Signs

Clinical symptoms that commonly occur together with bloating include: [25][26]

  • Loss of appetite
  • Pain or discomfort
  • Pawing or looking at flank
  • Lying down (recumbency)
  • Muscle loss
  • Lethargy
  • Pendulous or sagging abdomen

Depending on the other signs observed in your horse, different diagnoses may be indicated. If bloating occurs with other signs of colic, it may indicate an intestinal blockage or other issue requiring immediate intervention.

Bloating vs. Obesity

Early detection of bloating in horses is key to managing this symptom effectively. However, a bloated horse isn’t always obvious to owners and caretakers, with clinical signs sometimes being overlooked or mistaken for the horse’s normal body shape.

It’s also important to distinguish between bloating and obesity in horses. Overweight horses can exhibit a bloated appearance due to excess fat deposition in the abdominal area.

An estimated 31 – 45% of some equine populations are obese, and equine weight management is a growing concern worldwide. [24] Regularly monitoring your horse’s body condition score (BCS) can help you determine whether your horse is bloated or if they are simply gaining weight.

The Henneke system is the most commonly used method for body condition scoring in horses. This system rates horses on a scale from 1 to 9 as follows: [4][5]

  • Score 1: Poor or Emaciated
  • Score 2-3: Underweight
  • Score 4-6: Lean, Moderate or Moderately ‘Fleshy’ (Ideal)
  • Score 7: Overweight or ‘Fleshy’
  • Score 8-9: Fat or Obese

Assessing your horse’s condition score involves visually and manually examining the following six areas of the horse’s body. The areas where horses tend to carry extra fat are as follows:

  • Neck/Crest
  • Withers
  • Behind the Shoulder
  • Rib Cover
  • Rump
  • Tail Head

When body condition scoring a horse, each area is assigned a score based on the amount of fat cover and muscle definition observed. The scores from each area are combined to determine the overall condition of the horse.

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Common Causes of Bloating

Bloating can arise due to a range of potential causes and conditions, from feeding and management practices to more complex health issues. In horses some of the most common causes of bloating include the following:

1) Hay Belly

Bloating in horses is often associated with hay belly, a condition in which partially-digested fibrous material accumulates in the hindgut. Horses with a hay belly develop a large, pendulous abdomen, often appearing rounded or pregnant. [3]

It’s easy to mistake hay belly with a horse carrying excess body condition, but this form of bloating usually indicates an underlying health issues or dietary concern and not excess fat accumulation. [10] A horse that is genuinely overweight or obese is expected to have excess fat deposits around its entire body, not just in the abdominal area. [10]

Hay belly commonly occurs in horses fed poor-quality forage, with high levels of indigestible fiber and insufficient nutritional value. This material lingers in the hindgut, increasing gut fill and causing distention of the abdomen. Horses with hay belly might also have ribs showing and a concave appearance along their topline, along with a poor coat. [3]

Although hay belly does not pose an immediate health threat, it indicates reduced digestive efficiency, possibly due to dental issues or imbalances in the hindgut microbiome. Left untreated, these conditions could impact nutrient absorption and overall health in the horse. [14]

Several feeding strategies and nutritional interventions can help improve hay belly in affected horses. However, it is important to consult your veterinarian before assuming that bloating is caused by hay belly to rule out other serious conditions.

2) Colic

Colic broadly denotes abdominal pain in horses, arising from various causes, including gas accumulation, impaction, twists, or displacements in the intestines. Colic accompanied by abnormal accumulation of gas in the gastrointestinal tract can lead to bloating or abdominal distension. [14]

Horses experiencing colic may struggle to pass gas or stool and show signs of discomfort, including restlessness, pawing at the ground, rolling, or frequently looking at their flanks.

Horses with colic require immediate veterinary attention to identify the underlying cause and provide appropriate treatment. Treatment may involve medications to alleviate pain and discomfort, along with procedures like nasogastric intubation to release gas and alleviate pressure in the digestive tract. [15]

Nasogastric intubation should only be performed by a veterinarian. There is no safe way to intubate a horse at home.

 

3) PPID or Cushing’s

Horses with Pituitary Pars Intermedia Dysfunction (PPID), also known as Cushing’s disease, may develop a characteristic pot belly appearance as a result of metabolic changes associated with the condition. [16][17]

A common sign of Cushing’s disease in horses is abnormal fat distribution, particularly along the crest of the neck, tailhead, above the eyes and in the abdominal region.

This accumulation of abdominal fat gives some horses a bloated appearance, where the belly appears disproportionately larger than the rest of the body.

Muscle wastage along the spine may also contribute to the development of a pot belly, resulting in a sagging topline and underline. Older horses with PPID typically exhibit more severe muscle wastage. [17]

4) Parasites

Bloating in horses is sometimes associated with parasites, particularly gastrointestinal worms like strongyles, ascarids, and tapeworms. These parasites can cause significant damage to a horse’s gastrointestinal (GI) tract, compromising normal digestive function and leading to inflammation. [18]

Damage to the intestinal tissues can impair the horse’s ability to digest and absorb nutrients from food. This can result in secondary nutritional deficiencies, potentially leading to issues maintaining muscle mass and overall body condition.

In horses heavily infested with parasites, a condition known as ascites can develop, characterized by the accumulation of fluid within the abdominal cavity. This leads to abdominal distension and discomfort in the affected horses. [19]

Implementing effective deworming protocols and conducting regular fecal egg counts (FEC) to measure the number of parasite eggs in a horse’s feces are essential steps in managing and preventing parasitic infestations.

5) Edema

Edema is characterized by the abnormal accumulation of fluid in the body’s tissues, resulting in swelling. This condition can arise from inflammation or a blockage in the lymphatic system. [20]

Fluid build-up may occur in several parts of the body, including the abdomen. Ventral edemas are typically firm and doughy to the touch and can be found in the lowest part of the abdomen.

If ventral edema is observed in a horse, consult a veterinarian for a thorough evaluation, as it could indicate serious underlying health conditions, including heart failure.

6) Improper Chewing

Dysmastication refers to impaired chewing ability in horses due to various factors, such as dental issues causing discomfort. This discomfort might lead horses to swallow food without proper chewing [14]

Horses can also exhibit bolting, a behavior characterized by rapid food consumption without sufficient chewing. This often results in the horse swallowing large chunks of feed, which can cause digestive issues and potential choking hazards.

Improper chewing can disrupt the normal dietary balance and affect the breakdown of food in the colon. This disruption can alter the fermentation process conducted by hindgut bacteria, potentially leading to dysbiosis – an overgrowth of certain bacterial strains. [21]

Dysbiosis can contribute to an excess buildup of gas in the horse’s digestive system, resulting in bloating or gaseous distension.

If you suspect dental issues may be contributing to bloating, consult your veterinarian or equine dental specialist. Regular dental check-ups can help identify any worn, broken, abnormal or sharp teeth that may be interfering with proper chewing.

Treatment

Treatment of bloating in horses requires different approaches depending on the underlying cause of the horse’s symptoms. Your veterinarian will determine an appropriate treatment plan after a thorough examination and diagnostic tests.

Treatment may include: [11][23][26]

  • Dietary Management: Adjusting the horse’s diet to reduce gas production, such as reducing grain intake or switching to a more digestible forage
  • Protein Supplementation: Horses with hay belly may have a protein deficiency, leading to poor topline and muscle loss; treatment includes ensuring adequate protein intake by adding alfalfa and other high-quality protein sources to support muscle mass
  • Medication: Administering drugs to relieve gas, pain, or address specific conditions contributing to bloating
  • Fluid Therapy: Providing fluids to address dehydration and support normal digestive function
  • Exercise and Movement: Encouraging gentle movement to help stimulate the digestive system and release trapped gas
  • Surgical Intervention: In cases where bloating is due to a physical obstruction or other severe issues, surgery might be necessary to investigate and resolve the problem

Other treatments may be recommended by your veterinarian depending on their diagnosis. Supportive follow-up care and adjustments based on the horse’s response to treatment are also important for managing bloating and preventing recurrence.

How to Prevent Bloating

Proper feeding and management practices play a critical role in preventing bloating in horses. Working with an equine nutritionist can help you identify strategies to support your horse’s gut health and reduce factors that contribute to bloating.

An important strategy is to feed small, frequent meals throughout the day to support optimal digestive function. Large meals can overwhelm the digestive system, potentially leading to dysbiosis and hindgut dysfunction.

Also ensure that your horse has constant access to clean, fresh water to support the transit of feed through the digestive tract and prevent impaction.

Forage Quality

A key aspect of bloating prevention is selecting the right quality forage for your horse. [1] Forage quality is determined by multiple factors including nutritional content, digestibility, hygienic status, and overall suitability of the plant material. Typically, forage is categorized as low, moderate or high quality.

During the early stages of the growing season, forage plants (i.e. grass and legumes) are in their vegetative stage, providing high-quality, nutrient-rich, leafy growth. As the season progresses, plants transition into their reproductive stage, becoming lower quality, less nutritious and more fibrous. [1][6]

An increase in the fiber content of plants often accompanies a decrease in digestibility and protein content. Fiber-rich plant material is structurally complex and resistant to enzymatic breakdown in the digestive tract, making it challenging for horses to extract nutrients efficiently.

Horses with a history of bloating may benefit from higher-quality, more digestible hay to support hindgut function and prevent hay belly. [3]

Feeding high-quality hay also makes it possible to reduce the horse’s total feed volume while still meeting their nutritional needs. This helps decrease the gut’s workload by processing less dry matter.

The best way to evaluate forage quality is to submit a hay sample for analysis. An equine nutritionist can help you interpret the results of your forage analysis to determine whether any changes are required.

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Hygienic Quality

Providing hygienic hay is also key to maintaining your horse’s health and well-being. Fresh, clean hay significantly reduces the risk of digestive upset and impaction colic in horses. [8]

Hay contaminated with dust, mold spores, and harmful particles can also exacerbate respiratory conditions such as allergies, Equine Asthma (EA), and heaves or Recurrent Airway Obstruction (RAO) in horses. [9] These contaminants irritate the respiratory tract, causing inflammation, coughing, and labored breathing.

Nutritional Supplements

Some horses may benefit from nutritional supplements to support digestive function and maintain a healthy gut microbiome.

Probiotics

The horse’s digestive tract features a diverse microbiome of bacteria, protozoa, and fungi which aid in the breakdown and fermentation of fibrous plant material. These microorganisms are critical for normal digestion. [12]

An imbalance in this microbial community, known as gut dysbiosis, can negatively affect the horse’s digestive health by disrupting normal fiber fermentation and impacting the immune system.

Probiotics are live microorganisms, typically bacteria or yeast, that provide benefits to horses when consumed in sufficient amounts. Feeding probiotics to horses can help balance the gut microbiome and support digestive function. [13]

In particular, giving horses a yeast supplement, such as Saccharomyces cerevisiae, can promote nutrient absorption and improve fiber fermentation, potentially reducing factors that contribute to bloating.

Digestive Enzymes

Digestive enzymes are natural chemicals that break down different dietary components into smaller parts that can be absorbed. These enzymes can be found in the horse’s saliva, stomach, small intestine and hindgut.

Supplementing your horse’s diet with digestive enzymes can further support digestion by enhancing the breakdown of nutrients, ensuring more efficient absorption, and potentially reducing the risk of bloating.

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Summary

Bloating in horses is a common concern that can range from mild to life-threatening. Feeding a balanced, forage-based diet tailored to your horse’s individual needs can help prevent nutrition-related cases of bloating.

  • Familiarize yourself with the signs of bloating in horses and consult with your veterinarian if you suspect your horse is affected.
  • Your veterinarian will determine a treatment plan based on the underlying causes of your horse’s condition.
  • Feed appropriate hay quality for your horse’s condition and activity level to support weight management and digestive health.
  • Work with an equine nutritionist to identify and address dietary factors contributing to bloating or hay belly.

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References

  1. Ermers C. et al., The Fibre Requirements of Horses and the Consequences and Causes of Failure to Meet Them. Anim. Open Access J. MDPI. 2023. View Summary
  2. Merritt A. and Graham M., Abdomen: distention in Horses (Equis). Vet Lexicon.
  3. Overweight Horse. AAEP. 2005.
  4. Henneke D.R. et al., Relationship between Condition Score, Physical Measurements and Body Fat Percentage in Mares. Equine Vet. J. 1983. View Summary
  5. Jensen R.B. et al., Body Condition Score, Morphometric Measurements and Estimation of Body Weight in Mature Icelandic Horses in Denmark. Acta Vet. Scand. 2016.
  6. Majewski C., Hay Quality. 2017. Accessed Feb. 14, 2024.
  7. Longland A.C., Nutritional assessment of forage quality. In: Forages and grazing in horse nutrition. Academic Publishers. 2012.
  8. Pisch C. et al., Effect of Hay Steaming on the Estimated Precaecal Digestibility of Crude Protein and Selected Amino Acids in Horses. Anim. Open Access J. MDPI. 2022. View Summary
  9. Séguin V. et al., How to Improve the Hygienic Quality of Forages for Horse Feeding. J. Sci. Food Agric. 2012. View Summary
  10. Kosolofski H.R. et al., Prevalence of Obesity in the Equine Population of Saskatoon and Surrounding Area. Can. Vet. J. 2017. View Summary
  11. Gray L., Nutrition: The Key to Unlocking Your Horse’s Health.AAEP.
  12. Garber A. et al., Abrupt Dietary Changes between Grass and Hay Alter Faecal Microbiota of Ponies. PLoS ONE. 2020.
  13. Schoster A. et al., Probiotic Use in Horses – What Is the Evidence for Their Clinical Efficacy?. J. Vet. Intern. Med. 2014. View Summary
  14. Easley J., Introduction to Digestive Disorders of Horses. Merck. 2019.
  15. Munsterman A.S., Equine Emergency Procedures – Emergency Medicine and Critical Care. Merck. 2019.
  16. Young A.E., Pituitary Pars Intermedia Dysfunction. UC Davis School of Veterinary Medicine. 2020.
  17. Ireland J.L. and McGowan C.M., Epidemiology of Pituitary Pars Intermedia Dysfunction: A Systematic Literature Review of Clinical Presentation, Disease Prevalence and Risk Factors. Vet. J. 2018. View Summary
  18. Baxter R. and Kennedy M., Strongyle infestation: large in Horses (Equis). Vet Lexicon.
  19. Stewart A.J., Intestinal Disorders Other than Colic in Horses. Merck. 2019.
  20. Jones W.W., Ventral Edema in Horses Testing Positive for Potomac Horse Fever. Can. Vet. J. 1990. View Summary
  21. Scantlebury C.E. et al., Recurrent Colic in the Horse: incidence and Risk Factors for Recurrence in the General Practice Population. Equine Vet. J. 2011.
  22. Miller, K. F. & Moore-Colyer, M., Understanding Hay Quality: Even “Good” Hay Can Have Bad Things In It”. American Association of Equine Practitioners (AAEP).
  23. Novak, S. & Shoveller, A. K., Nutrition and Feeding Management for Horse Owners. Alberta Agriculture and Rural Development. 2008.
  24. Rendle, D. et al. Equine obesity: current perspectives. UK-Vet Equine. 2018.
  25. Thal, D. et al. Bloated Belly, Distended Abdomen. Horse Side Vet Guide.
  26. Thal, D. et al. Abdominal Pain, Colic Signs. Horse Side Vet Guide.