The Truth About Exercise-Induced Inflammation in Horses
The Signs, Causes, and Nutritional Support for Successful Targeted Results
For performance horses, pushing their limits is part of the job description. Whether they
are racing, jumping, performing dressage, or working on the ranch, their muscles
undergo significant stress during exercise.
While some degree of muscle fatigue or soreness is expected after strenuous activity, sometimes this response goes beyond normal recovery. This is where exercise-induced inflammation comes into play, potentially impacting comfort, performance, and overall well-being.
Understanding the spectrum of exercise-induced muscle issues is crucial. From subtle stiffness to severe conditions like ‘tying-up’ or exertional rhabdomyolysis (ER), are crucial issues to be understood.
Identifying the signs early and understanding the underlying causes are the first steps in effective management and support.
This article will delve into the signs to watch for, the common triggers and conditions behind exercise-induced muscle problems. Also highlighted, is how targeted nutritional support plays a vital role in regulating the inflammatory response and supports muscle health.
What You Need To Know To Understand Muscle, Exercise And Inflammation In Horses
Horse muscles are incredible powerhouses, contracting and relaxing rapidly to fuel
movement. During exercise, especially at high intensities or for prolonged durations,
muscle fibres experience microscopic tears and metabolic stress. This is a natural part
of conditioning, as the body repairs these micro-damages and builds stronger muscle.
Simultaneously, intense muscle activity generates reactive oxygen species, leading to oxidative stress, which can further damage muscle cells.
Exercise-induced damage can be compounded by other factors creating an overwhelming inflammatory response. It can manifest as mild post-exercise stiffness to severe muscle cramping and breakdown in conditions like rhabdomyolysis (tying-up).
How To Better Recognize The Signs Of Exercise-Induced Inflammation
The signs of exercise-induced muscle problems can vary in severity. Being attuned to your horse’s behaviour and physical condition after exercise is key to early detection.
Mild Signs of Inflammation in Horses:
Signs can be subtle and mistaken for simple fatigue or stiffness.The following key points should be noted and reviewed:
- Subtle changes in gait or reluctance to move forward freely.
- Mild stiffness or soreness, particularly in the hindquarters or loin area, often more
noticeable the day after exercise. - Reluctance to stretch or bend.
- Reduced performance or unwillingness to work at previous levels.
Severe Signs of Inflammation in Horses (Tying-Up/Exertional Rhabdomyolysis):
The following signs are more dramatic and require immediate attention:
- Reluctance or complete inability to move, especially the hind limbs.
- Hard, firm, and painful muscles, commonly in the hindquarters and across
the loin. - Sweating, sometimes profusely, even after exercise has stopped.
- Increased heart rate and respiratory rate, indicating pain and distress.
- Trembling or fasciculations (muscle twitching) in the affected areas.
- Anxious or distressed expression.
- Dark-coloured urine (brown or red) due to the presence of myoglobin
released from damaged muscle cells. The presence of myoglobin is a serious sign and requires urgent veterinary care.
Recognizing these signs, especially the subtle ones, allows for timely intervention
before a mild issue escalates to a severe episode.
Quickly Identify The Causes Of Inflammation In Horses
Exercise-induced muscle issues aren’t always just about working too hard. They can
stem from a combination of factors, including exercise intensity, conditioning, nutrition,
and underlying genetic predispositions. Causes are often categorized as sporadic or chronic/genetic.
Sporadic Causes of Inflammation in Horses
These episodes typically occur in horses without a history of muscle problems. Sporadic causes are often linked to specific management errors or circumstances:
#1. Exercise Exceeding Fitness:
Asking a horse to perform beyond its current conditioning level.
#2. Sudden Changes:
Abrupt increases in exercise intensity, duration, or changes in routine. An example of this is ‘Monday Morning Disease,’ which is described as resting for a few days and then returning to hard work.
#3. Insufficient Warm-up or Cool-down:
Failing to adequately prepare muscles for work or properly cool them down afterwards.
#4. Nutritional Imbalances:
Deficiencies in key nutrients like electrolytes, selenium, or vitamin E, which are crucial for muscle function and antioxidant defense. Imbalanced diets, particularly those high in non-structural carbohydrates (NSC), can also contribute to nutritional imbalances.
#5. Exercising While Sick or Stressed:
A compromised state can make muscles more susceptible to damage.
Chronic and Genetic Causes of Inflammation in Horses:
These conditions lead to recurrent episodes and often have a genetic component or underlying metabolic abnormality.
#1. Polysaccharide Storage Myopathy (PSSM):
A condition where muscles abnormally store glycogen. PSSM Type 1 is linked to a specific genetic mutation (GYS1 gene), while Type 2 has similar symptoms but without the known mutation. PSSM horses often tie-up, especially after rest periods or with diets high in starch/sugar.
#2. Recurrent Exertional Rhabdomyolysis (RER):
Commonly seen in Thoroughbreds, Standardbreds, and sometimes Arabians, RER is often linked to abnormalities in calcium regulation within muscle cells. Episodes are frequently triggered by excitement, stress, or high-energy diets and are more common in fillies and mares.
#3. Myofibrillar Myopathy (MFM):
Identified more recently, particularly in Arabians and some Warmbloods, MFM involves disorganization of the muscle’s contractile elements (myofibrils).
#4. Malignant Hyperthermia (MH):
A rare, genetic condition primarily in Quarter Horses and related breeds. MH is triggered by stress, exercise, or certain anesthetics, leading to severe muscle rigidity, heat production, and potential tying-up.
How To Pinpoint and Diagnose Exercise-Induced Inflammation In Horses
If you suspect your horse is experiencing exercise-induced muscle issues, especially atying-up episode, call your veterinarian. A proper diagnosis is essential for effective treatment and management.
The Diagnostic Process Typically Involves:
#1. Veterinary Examination & History:
Your vet will perform a physical exam and assess the muscle pain and stiffness. Next, the vet will ask detailed questions about the horse’s exercise routine, diet, and any previous episodes.
#2. Blood Work:
Blood tests are key to assessing muscle damage. The enzymes Creatine Kinase (CK) and Aspartate Aminotransferase (AST) are released into the bloodstream when muscle cells are damaged.
CK levels typically peak 4-6 hours after the event and decline rapidly. Meanwhile, AST levels rise more slowly (peaking 24-48 hours) but remain elevated longer, indicating more sustained damage. Lactate Dehydrogenase (LDH) may also be measured.
#3. Urinalysis:
Checking a urine sample can reveal the presence of myoglobin, indicating significant muscle breakdown. Monitoring kidney function may also be necessary in severe cases.
#4. Muscle Biopsy:
In cases of suspected chronic myopathies (PSSM, MFM), a small muscle tissue sample may be taken for microscopic examination. The purpose of this is to identify characteristic abnormalities in glycogen storage or myofibril structure.
#5. Genetic Testing:
Genetic tests are available for specific mutations associated with PSSM1 and Malignant Hyperthermia (MH). These tests can confirm a diagnosis and guide breeding decisions.
How to Help: Management, Treatment, and Nutritional Support
Managing exercise-induced muscle problems involves immediate care during an acute episode, followed by long-term strategies to prevent recurrence. Nutritional support plays a critical role in recovery and prevention, particularly in regulating the inflammatory response and supporting muscle health.
Immediate Care for Acute Episodes
If your horse shows severe signs of tying-up:
- Stop exercising immediately.
- Do not force the horse to move.
- Move the horse to a quiet, deeply bedded stall.
- If trailering is absolutely necessary, do so carefully and slowly.
- Provide fresh water and plain salt.
- Call your veterinarian immediately.
Veterinary treatment may include:
- Pain relief (NSAIDs)
- Muscle relaxants (like methocarbamol or dantrolene)
- Intravenous fluids to combat dehydration and protect the kidneys from myoglobin, and electrolyte supplementation.
- Stall rest is typically required until blood enzyme levels normalize.
Long-Term Management and Prevention
Preventing future episodes, especially in horses prone to chronic conditions, relies on
consistent management.
#1. Consistent Exercise:
Maintaining a regular, consistent exercise routine is vital. Avoid sudden changes in intensity or duration and minimize periods of stall rest followed by strenuous work. Gradually condition the horse for its required workload.
#2. Proper Warm-up and Cool-down:
Always incorporate a minimum of 10-15 minutes of walking/light work before and after more intense exercise.
#3. Stress Reduction:
Minimize sources of stress or excitement, as these can trigger episodes in susceptible horses like those with RER.
#4. The POWER of Nutritional Support:
Diet is a cornerstone of managing and preventing exercise-induced muscle issues, especially for chronic myopathies, but also for supporting recovery in any horse.
#5. Foundation:
A diet based on high-quality forage (hay or pasture) is essential. For horses with PSSM, managing the intake of non-structural carbohydrates (starches and sugars) is crucial. This often requires testing hay and limiting grains/sweet feeds.
#6. Energy Source:
For horses needing calories, particularly those with PSSM, replacing grain with fat is often recommended. Fat provides dense, ‘cool’ energy without the starch associated with muscle problems.
#7. Replenishing Losses:
Exercise leads to electrolyte losses through sweat (sodium, potassium, chloride, calcium, magnesium). Replenishing these is vital for proper muscle function and preventing cramps. A balanced electrolyte supplement is often necessary, especially for horses in work. Calcium and magnesium are particularly important for muscle relaxation and function.
#8. Fighting Damage:
This is where antioxidants and healthy fats shine in modulating inflammation and oxidative stress. Exercise-induced inflammation and oxidative stress can damage muscle cells. Antioxidants like Vitamin E and Selenium are critical for scavenging free radicals and protecting cell membranes.
Providing a bioavailable source of high-grade Vitamin E is particularly beneficial for performance horses. Omega fatty acids, especially Omega-3s, have natural anti-inflammatory properties, helping to regulate the body’s inflammatory response post-exercise. Including a balanced source of Omega-3 and Omega-6 fatty acids supports cellular health and recovery.
#9. Muscle Metabolism Support:
Specific nutrients may aid certain conditions. For PSSM horses, L-Carnitine or Acetyl-l-carnitine can help improve muscle metabolism. For horses with MFM, ensuring adequate protein and amino acids (like Leucine) or supplementing with HMB (beta-hydroxy-beta-methylbutyrate) may help support muscle protein synthesis.
#10. Ensuring a Balanced Diet:
Beyond specific issues, ensuring the horse receives a balanced diet with adequate vitamins and minerals is fundamental to overall muscle health.
#11. Working with an Equine Nutritionist:
Consulting with a qualified equine nutritionist can help. The nutritionist can create a tailored diet plan based on your horse’s specific needs, diagnosis, workload, and forage analysis.
Owners can significantly support their horse’s muscles and help mitigate exercise-induced inflammation. It is important to address diet, focus on balanced nutrients, appropriate energy sources, and targeted support like antioxidants and omegas.
A Complete Prognosis for a Successful Recovery
The prognosis for horses experiencing sporadic tying-up is generally good with the appropriate immediate treatment and subsequent management changes. Recovery time varies depending on severity. Mild cases may require a few weeks of recovery, while severe rhabdomyolysis requires extensive rehabilitation and may need several months.
Horses with chronic myopathies like PSSM or RER require lifelong, careful
Management. This involves strict dietary control, consistent exercise, and stress reduction to minimize the frequency and severity of episodes.
While these conditions cannot be cured, they can often be effectively managed, allowing many affected horses to return to useful athletic careers.
For Best Results, Have The Horse Seen By A Veterinarian
Always consult your veterinarian if:
- Your horse shows any signs of severe tying-up (reluctance to move, hard painful muscles, sweating, dark urine). This is an emergency.
- Your horse shows repeated episodes of stiffness or poor performance after exercise.
- You are unsure about the cause of your horse's muscle discomfort.
- You need help developing a management plan for a horse diagnosed with a. chronic myopathy
Your veterinarian is your best resource for diagnosing muscle issues and developing a
comprehensive plan that may include diet, exercise, and other therapies.
A Helpful Resource for Exercise-Induced Inflammation in Horses
Exercise-induced inflammation and related muscle issues are significant concerns for
horse owners. Recognizing the signs, understanding the potential sporadic and genetic
causes, and seeking a veterinary diagnosis are crucial steps.
While immediate veterinary care is paramount during acute episodes, long-term management relies on a more structured treatment. It is crucial to carefully plan exercises, stress reduction, and targeted nutritional support.
Owners can proactively support their horse’s muscle health by providing a diet rich in quality forage, balancing energy sources, and ensuring adequate electrolytes. The incorporation of potent antioxidants like Vitamin E and anti-inflammatory omega fatty acids help regulate the inflammatory response. Ultimately this helps to improve their comfort, performance, and longevity in their athletic pursuits.
Contact EC Nutraceuticals
If you are a veterinarian clinic, and would like to learn more about carrying our foundational liquid supplements that support equine & canine whole body health, please contact us at info@ecnutraceuticals.com.
If you are a horse or dog owner, and would like to use our products, please speak to your local vet about Structure Liquid Supplements by EC Nutraceuticals.
Cited Links:
https://www.merckvetmanual.com/musculoskeletal-system/myopathies-in-
horses/exertional-myopathies-in-horses
https://www.petmd.com/horse/conditions/musculoskeletal/chronic-inflammation-
horses
https://www.merckvetmanual.com/horse-owners/bone-joint-and-muscle-
disorders-in-horses/muscle-disorders-in-horses
[https://esc.rutgers.edu/factsheet/5531/](https://esc.rutgers.edu/factsheet/5531/)
https://vetster.com/en/symptoms/horse/exercise-intolerance-in-horses
https://www.petmd.com/horse/conditions/musculoskeletal/exertional-
rhabdomyolysis-horses
https://www.sciencedirect.com/science/article/abs/pii/S0737080612001529
https://vaequine.com/equine/exertional-rhabdomyolysis-tying-up/
https://ker.com/nmdl/resources/exertional-rhabdomyolysis/
https://en.wikipedia.org/wiki/Equineexertionalrhabdomyolysis
https://pubmed.ncbi.nlm.nih.gov/21059019/ (Cited for Omega-3 anti-inflammatory
properties)
https://journals.physiology.org/doi/10.1152/japplphysiol.00971.2016 (Cited for
exercise-induced inflammation/oxidative stress markers)
https://vtechworks.lib.vt.edu/bitstreams/fa1a9c15-4b9b-4b2a-a560-
00643a78c694/download (Cited for MFM/HMB)
https://beva.onlinelibrary.wiley.com/doi/full/10.1111/evj.14128 (Cited for
PSSM/L-Carnitine)