Key Insights
  • Chronic inflammation can persist beyond healing and damage healthy tissues over time
  • Signs may include stiffness, reduced performance, weight loss, coughing, poor hoof quality, and delayed healing
  • Joint, metabolic, digestive, respiratory, infectious, and immune-mediated disorders can sustain inflammation
  • No single test can diagnose every form of chronic inflammation in horses
  • Effective treatment depends on identifying and managing the underlying condition
  • Balanced nutrition, appropriate exercise, environmental changes, and veterinary care can support recovery

Chronic inflammation in horses refers to a prolonged immune response that can accompany disorders affecting the joints, airways, digestive tract, metabolism, and other body systems. When inflammatory activity continues beyond its useful role in healing, it may contribute to tissue damage and reduced function over time.

Because chronic inflammation is a process rather than a specific disease, effective management depends on identifying what is sustaining the inflammatory response. Changes in comfort, body condition, exercise tolerance, or performance may warrant veterinary investigation, but these signs can have many possible causes.

Keep reading to learn about the signs and conditions associated with chronic inflammation, how veterinarians identify underlying causes, and how nutrition, exercise, environmental changes, and medical care may support affected horses.

Chronic Inflammation in Horses

Inflammation is a normal part of the body’s response to injury, infection, irritation, or other tissue damage. The horse’s immune system triggers inflammation to help eliminate harmful organisms, remove damaged cells, and begin healing.

Acute inflammation is short-lived and usually resolves as the affected tissue heals. Chronic inflammation persists or repeatedly returns, potentially interfering with normal tissue function over time. Instead of supporting recovery, ongoing inflammation can gradually damage healthy tissues and contribute to disease progression. [1]

Chronic inflammation can be difficult to recognize because it rarely begins with one obvious event. Depending on its cause and location, a horse may develop gradual changes such as persistent stiffness, slower recovery after exercise, a recurring cough, unexplained weight loss, or declining performance.

However, chronic inflammation does not always produce clear outward signs, and these changes do not confirm that inflammation is present.

Similar signs can occur with joint disease, endocrine disorders, respiratory disease, infection, digestive problems, and other conditions.

Chronic inflammation in horses is commonly associated with: [2]

Inflammation may also be limited to one area rather than affecting the horse systemically.

A veterinary examination is needed to identify the affected body system and determine why the signs are continuing. Tests for inflammatory markers can provide useful information, but they cannot identify the source or cause on their own. [2]

Understanding how chronic inflammation differs from a normal short-term response can help owners recognize when gradual or persistent changes deserve attention. Once the underlying cause has been identified, veterinary care, nutrition, exercise, and day-to-day management can be tailored to the individual horse.

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Signs of Chronic Inflammation

The signs of chronic inflammation in horses vary depending on the underlying disease and the body systems affected. Unlike acute inflammation, which often causes obvious swelling, heat, and pain, chronic inflammation usually develops gradually and may produce subtle clinical signs that become more noticeable over time. [1]

Musculoskeletal Signs

Inflammation affecting the joints, tendons, ligaments, or muscles may result in: [3][4][5][6]

These changes may reflect pain, reduced mobility, or impaired tissue function, but they do not identify the affected structure or underlying disorder. [2][5]

General Health Changes

Long-term inflammation may also affect overall health, leading to: [1][3][2]

Because these changes can develop slowly, tracking the horse’s weight, muscle condition, coat, and hoof quality over time may help owners recognize emerging concerns.

Other Clinical Signs

Depending on the underlying condition, horses may also develop: [7][8][9][10][11]

Because these signs occur with many different diseases, veterinary evaluation is needed to determine the underlying cause. [2]

When to Call the Veterinarian

Horses with persistent or unexplained health changes should be evaluated by a veterinarian. Because the signs of chronic inflammation overlap with many other conditions, delaying evaluation may also delay appropriate treatment.

Schedule a veterinary examination if your horse develops:

  • Persistent stiffness or lameness
  • Reduced athletic performance
  • Unexplained weight loss or muscle loss
  • Recurring infections
  • Poor hoof quality or delayed wound healing
  • Chronic coughing or breathing difficulty
  • Persistent digestive problems
  • Signs of ongoing pain or discomfort

A veterinarian can assess the affected body system, investigate the underlying cause, and determine whether diagnostic testing or treatment is needed.

Seek emergency veterinary care if your horse has severe breathing difficulty, collapses, is unable to bear weight, shows signs of laminitis, has severe or persistent signs of colic, or develops rapidly worsening symptoms.

Acute vs. Chronic Inflammation

Acute and chronic inflammation are distinguished mainly by their duration and physiological purpose, not simply by the severity of their signs. [1]

Acute inflammation develops rapidly after an injury, infection, or other challenge. The affected area may become warm, swollen, painful, or difficult to use, but these changes are part of a coordinated response that helps contain damage and initiate tissue repair. [1] As healing progresses, the acute inflammatory response should decrease.

Chronic inflammation persists when the inflammatory response does not fully resolve or when the body continues responding to an ongoing problem. Its signs may be less noticeable from day to day, but persistent immune activity can gradually interfere with normal tissue function. [1][9][10]

Inflammation may remain localized to one structure, such as a joint or tendon, or have broader effects when immune signals circulate throughout the body.

Systemic inflammation may produce general changes such as poor appetite, weight loss, fatigue, or reduced performance. [1][2][5]

The pattern of inflammation can help determine the underlying cause and appropriate veterinary investigation. A recent strain, for example, requires different consideration than progressive joint disease, an endocrine disorder, or recurring airway irritation.

Veterinarians assess whether inflammation is acute or chronic, localized or systemic, along with the duration of signs and the body system affected. [12][9][10]

Table 1. Acute vs. chronic inflammation in horses

Key Difference Acute Inflammation Chronic Inflammation
Onset
  • Begins quickly after injury, infection, or irritation
  • Develops gradually, persists, or repeatedly returns
Duration
  • Short-lived and decreases as healing progresses
  • Continues beyond the expected healing period
Purpose
  • Contains damage and initiates tissue repair
  • Reflects an unresolved or ongoing stimulus
Common Signs
  • Heat, swelling, pain, and reduced function
  • Stiffness, slower recovery, weight loss, coughing, or declining performance
Effects on Tissues
  • Usually supports normal healing
  • May damage healthy tissues and reduce function over time
Management Focus
  • Support healing and address the immediate cause
  • Identify and manage the condition sustaining the response

Conditions Associated with Chronic Inflammation

Persistent inflammation can arise when damaged tissues continue to signal for repair or when infection, immune dysfunction, or chronic disease keeps the immune system active. The body system involved shapes the signs and long-term effects.

Osteoarthritis & Musculoskeletal Disease

Osteoarthritis is a common source of chronic inflammation, particularly in older and athletic horses. Changes within the joint contribute to pain, stiffness, and progressive cartilage degeneration. [1][5]

Chronic tendon injuries, ligament injuries, and back pain may also involve prolonged inflammation during healing. This inflammatory activity can contribute to: [1]

  • Scar tissue
  • Reduced flexibility
  • Loss of function

Metabolic Disorders

Insulin dysregulation is the central feature of equine metabolic syndrome (EMS) and is strongly associated with an increased risk of laminitis. Although many horses with EMS are overweight, insulin dysregulation can also occur in horses with a normal body condition. [12]

Obesity is associated with low-grade chronic inflammation because adipose tissue releases signaling compounds that influence immune and inflammatory activity. Researchers are still investigating how these changes relate to EMS and other metabolic disorders. [12][13]

Pituitary Pars Intermedia Dysfunction (PPID) is an endocrine disorder that becomes more common with age. Older horses have a higher risk of PPID, which can alter hormonal regulation, immune function, and inflammatory responses. [14]

Digestive Disorders

Digestive disorders can contribute to chronic inflammation through different mechanisms depending on the part of the gastrointestinal tract affected.

Inflammatory bowel disease involves persistent inflammation within the intestinal wall, which can damage intestinal tissues and interfere with normal nutrient absorption. Chronic colitis causes ongoing inflammation of the colon and may disrupt normal barrier function. [7][8]

Damage to the intestinal lining may increase intestinal permeability, allowing bacterial products and other substances within the gut to interact more readily with the immune system. Researchers are investigating whether this disruption of the intestinal barrier, often referred to as “leaky gut,” can contribute to systemic inflammation in horses. [8]

Equine Gastric Ulcer Syndrome (EGUS) affects the stomach through different disease processes. Damage to the gastric mucosa can cause localized inflammation and persistent irritation of the stomach lining. This differs from inflammatory disease affecting the small intestine or colon, but ongoing mucosal injury can still maintain an inflammatory response. [7]

Horses with digestive disease may develop: [8]

These signs may result from impaired digestion, reduced nutrient absorption, pain, or altered gastrointestinal function associated with the underlying disorder. [7][8]

Respiratory Disease

Equine asthma and other chronic respiratory disorders can involve persistent airway inflammation. Affected horses may cough, breathe with greater effort, or show reduced exercise tolerance.

Clinical signs often vary with the horse’s environment and workload, so coughing or reduced exercise tolerance may come and go even when airway inflammation persists. [9][10]

Respiratory signs should not be attributed to inflammation without an examination. Infection, airway disease, cardiovascular problems, and other conditions can produce similar changes in breathing or performance.

Chronic Infections

Chronic infections can develop when an infection is not fully cleared or repeatedly returns. Continued exposure to the infectious agent can prolong immune activation and maintain inflammation over time. [1]

The signs vary depending on where the infection is located and may include: [1]

Some horses develop obvious recurring episodes of illness, while others show a gradual decline in appetite, body condition, or performance. [1]

Older horses and those with conditions that affect immune function, including Pituitary Pars Intermedia Dysfunction (PPID), may be more susceptible to persistent or recurring infections.

Because these signs can occur with many different conditions, veterinary testing may be needed to confirm an infection, identify the organism involved, and determine where the infection is located.

Immune-Mediated Disorders

In immune-mediated diseases, the immune system mistakenly targets the horse’s own tissues or continues responding after it is no longer needed. These conditions can affect a single body system or cause more widespread signs. [3]

Diagnosis is challenging because many symptoms overlap with other conditions, including infections, injuries, endocrine disorders, and other inflammatory diseases. [3]

Because chronic inflammation can arise from many different diseases, identifying the underlying cause is the first step toward effective treatment and long-term management.

Diagnosis

There is no single diagnostic test that can confirm chronic inflammation or identify its underlying cause in every horse.

A veterinary assessment for chronic inflammation begins by reviewing the horse’s history, including: [1]

  • When the signs started
  • Whether they are constant or intermittent
  • How they relate to exercise, feeding, season, environment, or recent illness

Changes in body weight, performance, medication use, and previous injuries can help narrow the possible causes. [1]

Your veterinarian will also conduct a physical examination based on the clinical signs your horse is experiencing. A horse with stiffness or lameness may need a detailed musculoskeletal assessment, while coughing or poor exercise tolerance may prompt closer evaluation of the respiratory and cardiovascular systems.

Weight loss or recurring digestive upset may require tests such as bloodwork, fecal analysis, abdominal ultrasound, gastroscopy, or intestinal biopsy, depending on the suspected cause.

Bloodwork can provide information about general health, immune activity, organ function, and possible infection, but the results must be interpreted alongside the clinical picture.

Diagnostic imaging may be used to assess joints, bones, tendons, ligaments, or other tissues. Additional tests are selected according to the body system involved rather than applied as a standard panel for every horse. [2]

Once the cause of inflammation is identified, the veterinarian can develop a treatment plan to address the underlying condition and restore normal function.

Follow-up evaluation may include repeating parts of the physical examination, bloodwork, imaging, or performance assessment. Tracking body weight, appetite, mobility, respiratory signs, and recovery after exercise can also help determine whether the management plan is working.

Treatment & Management

Chronic inflammation can result from many different diseases, so there is no universal treatment. Management depends on identifying the condition responsible for the inflammatory response and treating it appropriately. [1][2]

Treatment may also include measures to reduce inflammation, relieve pain, and maintain normal function. Depending on the diagnosis, this can involve medication, nutrition, exercise, rehabilitation, or changes to the horse’s environment.

Supportive care can improve comfort and function, but it does not replace treatment of the underlying condition.

Nutrition & Body Condition

Horses with chronic inflammation benefit from a diet that meets their nutrient requirements while supporting normal immune function, tissue repair, and a healthy body condition. Nutrition does not replace treatment of the underlying disease, but it can help address dietary factors that influence inflammatory activity and recovery.

A balanced, forage-based diet should provide adequate energy, protein, vitamins, and minerals. Deficiencies or imbalances can impair immune function, tissue repair, muscle maintenance, and other processes involved in recovery. The complete diet should be evaluated rather than relying on a single ingredient or supplement to manage inflammation. [15]

Maintaining a healthy body condition is also important. Fat tissue is biologically active and releases compounds involved in inflammatory signaling. Excess body fat can therefore contribute to low-grade systemic inflammation and is also associated with metabolic dysfunction. [4][14]

For overweight horses, gradual weight loss can be achieved through an appropriate forage program, controlled calorie intake, balanced vitamin and mineral intake, and exercise when suitable for the horse’s health and soundness.

Underweight horses and horses losing muscle require a different approach. Dental disease, poor forage quality, digestive disorders, pain, inadequate calorie or protein intake, and the underlying condition itself can contribute to weight or muscle loss. Increasing feed without identifying the cause may delay appropriate treatment. [7][8]

Omega-3 fatty acids are also relevant to nutritional support for chronic inflammation because they participate in pathways that regulate inflammatory signaling. The long-chain omega-3 fatty acids DHA and EPA are incorporated into cell membranes and contribute to the production of compounds involved in regulating inflammatory responses. Research on specific clinical applications in horses is still developing, so omega-3 supplementation should be used as nutritional support rather than as a treatment for the underlying disease. [16]

Mad Barn’s OmegaPrime+® is a concentrated omega-3 oil for horses that need higher levels of DHA and EPA without a large increase in dietary calories. Unlike plant-based oils that primarily provide ALA, which horses must convert to longer-chain omega-3s, OmegaPrime+ supplies DHA and EPA directly.

OmegaPrime+ is particularly beneficial for senior, metabolic, overweight, and performance horses that require concentrated omega-3 support without unnecessary calories. A 30 mL serving provides 6,000 mg DHA, 1,500 mg EPA, 6,900 mg ALA, and 750 IU of natural vitamin E to support normal inflammatory balance and antioxidant status.

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  • Extra-strength omega-3 oil
  • Normal inflammatory balance
  • Supports joint comfort
  • Skin, coat & respiratory health

You can work with an equine nutritionist to determine whether your horse’s diet provides the right amount of calories, protein, vitamins, minerals, fatty acids, and other nutrients for their needs. Submit your horse’s information for a free diet evaluation to identify nutrient gaps or imbalances and develop a feeding program suited to your horse.

Exercise & Chronic Inflammation

During exercise, muscles, tendons, ligaments, and joints are exposed to repeated mechanical loading. This can cause small amounts of tissue damage and trigger a short-term inflammatory response that helps remove damaged cells and initiate repair.

In a healthy horse, this response decreases during recovery as tissues adapt to the workload. Appropriate exercise can therefore support normal musculoskeletal function without causing persistent inflammation.

When workload and recovery are appropriately balanced, regular exercise supports: [17]

  • Joint mobility
  • Muscle mass
  • Cardiovascular fitness
  • Metabolic health

Exercise can be beneficial for horses with chronic inflammation, but the type and intensity of exercise should reflect the condition involved. For horses with obesity or insulin dysregulation, regular exercise may support weight management and improve insulin sensitivity. Horses with osteoarthritis may benefit from controlled movement to help maintain joint mobility and muscle strength. [5]

Horses recovering from tendon, ligament, or other musculoskeletal injuries require a structured rehabilitation plan that gradually increases loading as healing progresses.

Excessive training, rapid increases in workload, or inadequate recovery can increase tissue damage, prolong inflammation, and raise the risk of injury. Prolonged confinement can also contribute to muscle loss, stiffness, and declining fitness when stall rest is not medically necessary. [17][6]

Exercise recommendations should consider the horse’s diagnosis, soundness, age, current fitness, and stage of recovery. Horses with active laminitis, significant lameness, breathing difficulty, or an unresolved injury should be evaluated by a veterinarian before starting or increasing exercise.

Environmental Management

Environmental conditions can influence chronic inflammation by affecting exposure to allergens and pathogens, opportunities for movement, physical stress on the body, and the horse’s ability to rest and recover.

For horses with equine asthma or other respiratory diseases, reducing airborne irritants can help limit ongoing airway inflammation. This may include feeding low-dust forage, using low-dust bedding, improving barn ventilation, and soaking or steaming hay when appropriate. [11]

Other management practices that may help reduce factors contributing to chronic inflammation include:

  • Providing regular turnout and appropriate daily movement
  • Using safe, well-maintained footing to reduce unnecessary strain on joints and soft tissues
  • Maintaining a healthy body condition to reduce metabolic and mechanical stress
  • Providing adequate rest and recovery between periods of exercise or training
  • Maintaining clean stalls, paddocks, feeders, and water sources to reduce exposure to pathogens and environmental contaminants
  • Protecting horses from prolonged exposure to extreme heat, cold, or wet conditions
  • Maintaining consistent routines and appropriate social contact to reduce unnecessary stress
  • Addressing sources of ongoing pain, including poor hoof balance, dental problems, or improperly fitted tack

These practices should be selected according to the horse’s diagnosis, mobility, living conditions, and veterinary treatment plan.

These measures should be adapted to the horse’s diagnosis, mobility, respiratory needs, and living conditions.

Medications

A veterinarian may prescribe medications for the horse to reduce pain and inflammation and treat the underlying condition. The choice of medication depends on the horse’s diagnosis, the severity of the condition, and overall health.

Non-steroidal anti-inflammatory drugs (NSAIDs), such as phenylbutazone and flunixin meglumine, are commonly used to manage pain associated with musculoskeletal disorders and other inflammatory conditions. A veterinarian may also prescribe corticosteroids for certain respiratory, allergic, or immune-mediated diseases. [1][18]

Although these medications can be effective, they also carry a risk of side effects, particularly with prolonged use. Horses should receive them only under veterinary supervision and according to the veterinarian’s instructions.

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Prevention

Chronic inflammation is not always preventable in horses, but good management can reduce some risk factors and help address problems before they become persistent.

Horse owners can help reduce the risk of chronic inflammation by: [1][10][15]

  • Feeding a balanced, forage-based diet
  • Maintaining a healthy body condition
  • Scheduling routine dental and hoof care
  • Following veterinarian-recommended vaccination and parasite control programs
  • Seeking prompt veterinary care for illness or injury
  • Providing regular exercise appropriate for the horse’s age, health, and workload
  • Reducing unnecessary environmental and management stress

Regular monitoring can also help identify health changes early. Track changes in weight, muscle condition, hoof quality, coat condition, appetite, manure output, respiratory signs, soundness, and exercise tolerance. Gradual changes may indicate an underlying problem even when the horse does not appear acutely ill.

Early diagnosis and appropriate treatment of conditions associated with chronic inflammation may help limit ongoing tissue damage and improve long-term health.

Frequently Asked Questions

Here are some frequently asked questions about chronic inflammation in horses:

Summary

Chronic inflammation is a prolonged immune response associated with many equine diseases rather than a single diagnosis. Effective management requires veterinary investigation of the condition sustaining the response.

  • Signs may include stiffness, poor performance, weight loss, coughing, recurring infections, and delayed healing
  • Joint, metabolic, digestive, respiratory, infectious, and immune disorders can sustain inflammation
  • Diagnosis uses the horse's history, physical examination, and targeted testing
  • Treatment addresses the underlying condition while supporting comfort through nutrition, exercise, environmental changes, and medication
  • Routine care and early veterinary evaluation may limit tissue damage and improve outcomes
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References

  1. MacKay. R. J. Inflammation in Horses. Veterinary Clinics of North America: Equine Practice. 2000. View Summary
  2. Long. A. and Nolen-Walston. R. Equine Inflammatory Markers in the Twenty-First Century: A Focus on Serum Amyloid A. Veterinary Clinics of North America: Equine Practice. 2020. View Summary
  3. Durward-Akhurst. S. A. and Valberg. S. J. Immune-Mediated Muscle Diseases of the Horse. Veterinary Pathology. 2018. View Summary
  4. Pearson. W. et al. Exploring Relationships between Body Condition Score, Body Fat, Activity Level and Inflammatory Biomarkers. Journal of Animal Physiology and Animal Nutrition. 2018. View Summary
  5. te Moller. N. C. R. and van Weeren. P. R. How Exercise Influences Equine Joint Homeostasis. The Veterinary Journal. 2017. View Summary
  6. Horohov. D. W. et al. The Effect of Exercise and Nutritional Supplementation on Proinflammatory Cytokine Expression in Young Racehorses During Training. Journal of Equine Veterinary Science. 2012.
  7. Sykes. B. W. et al. European College of Equine Internal Medicine Consensus Statement—Equine Gastric Ulcer Syndrome in Adult Horses. Journal of Veterinary Internal Medicine. 2015. View Summary
  8. Stewart. A. S. et al. Alterations in Intestinal Permeability: The Role of the "Leaky Gut" in Health and Disease. Journal of Equine Veterinary Science. 2017. View Summary
  9. Lavoie-Lamoureux. A. et al. Markers of Systemic Inflammation in Horses with Heaves. Journal of Veterinary Internal Medicine. 2012. View Summary
  10. Ivester. K. M. and Couëtil. L. L. Management of Chronic Airway Inflammation in the Horse: A Systematic Review. Equine Veterinary Education. 2014.
  11. Westerfeld. R. et al. Effects of Soaked Hay on Lung Function and Airway Inflammation in Horses with Severe Asthma. Journal of Veterinary Internal Medicine. 2024. View Summary
  12. Durham. A. E. et al. ECEIM Consensus Statement on Equine Metabolic Syndrome. Journal of Veterinary Internal Medicine. 2019. View Summary
  13. Vick. M. M. et al. Relationships among Inflammatory Cytokines, Obesity, and Insulin Sensitivity in the Horse. Journal of Animal Science. 2007. View Summary
  14. Adams. A. A. et al. Effect of Body Condition, Body Weight and Adiposity on Inflammatory Cytokine Responses in Old Horses. Veterinary Immunology and Immunopathology. 2009. View Summary
  15. Nutrient Requirements of Horses: Sixth Revised Edition. National Academies Press. 2007. View Summary
  16. Elzinga. S. E. et al. Effects of Docosahexaenoic Acid–Rich Microalgae Supplementation on Metabolic and Inflammatory Parameters in Horses With Equine Metabolic Syndrome. Journal of Equine Veterinary Science. 2019. View Summary
  17. Rakowska. A. et al. How Inflamed Is the Horse in Training? Insights into Exercise-Induced Acute Phase Response in Endurance Horses. International Journal of Molecular Sciences. 2026. View Summary
  18. Knych. H. K. Nonsteroidal Anti-inflammatory Drug Use in Horses. Veterinary Clinics of North America: Equine Practice. 2017. View Summary