Learn what causes tying up in horses, the signs of exertional rhabdomyolysis, and how to manage and prevent episodes.
Tying up in horses refers to exertional rhabdomyolysis, a condition in which muscle fibers break down during or after exercise. Horses may become stiff, reluctant to move, and painful in the hindquarters. Prompt veterinary evaluation and careful management are essential to prevent complications.
Causes, Treatment, and Prevention of Exertional Rhabdomyolysis
“Tying up” is a term widely used in barns to describe a horse that suddenly becomes stiff, painful, and reluctant to move during or after exercise. The clinical term for this condition is equine exertional rhabdomyolysis (ER), which refers to exercise-associated skeletal muscle damage.
Understanding what occurs inside the muscle during a tying-up episode helps riders and trainers recognize the condition early, manage it appropriately, and reduce the risk of recurrence.
What Is Tying Up in Horses?
Equine exertional rhabdomyolysis is characterized by acute breakdown of skeletal muscle fibers associated with exercise.
When muscle cells are damaged, they release intracellular components into the bloodstream including:
- creatine kinase (CK)
- aspartate aminotransferase (AST)
- myoglobin
Elevated blood levels of CK and AST are commonly used by veterinarians to confirm muscle injury.
In severe cases, myoglobin released from damaged muscle fibers can appear in the urine, producing dark or coffee-colored urine and increasing the risk of kidney injury (Valberg, 2018).
What Happens in the Muscle During Tying Up?
During exertional rhabdomyolysis, muscle cells experience both metabolic disruption and structural damage.
Research has identified several mechanisms that contribute to tying up:
- abnormal calcium regulation inside muscle cells
- depletion of cellular energy stores
- accumulation of metabolic byproducts
- structural breakdown of muscle fibers
When calcium regulation fails inside the muscle cell, sustained muscle contraction can occur. This prolonged contraction damages muscle fibers and disrupts normal cellular function (Valberg, 2016).
Clinical Signs of Tying Up
The clinical signs of tying up can vary in severity depending on the extent of muscle damage.
Common signs include:
- stiff or painful hindquarter muscles
- shortened stride
- reluctance to move forward
- sweating and elevated heart rate
- firm or painful muscles on palpation
Affected horses often appear anxious because movement increases muscle pain.
Causes and Risk Factors for Tying Up
Tying up is considered a multifactorial condition, meaning that several contributing factors can influence risk.
Training Factors
- sudden increases in workload
- intense exercise after rest days
- poor conditioning
- inconsistent training schedules
Nutritional Factors
- high starch diets
- inadequate electrolyte balance
- insufficient dietary fat in some horses
Genetic Muscle Disorders
Some horses have underlying muscle diseases that predispose them to tying up episodes.
Examples include:
- Recurrent exertional rhabdomyolysis (RER)
- Polysaccharide storage myopathy (PSSM)
These conditions affect how muscle cells regulate calcium or store and use energy during exercise (Valberg, 2014).
Immediate Management of a Tying Up Episode
If tying up is suspected, prompt management is important.
Recommended steps include:
- Stop exercise immediately
- Contact your veterinarian
Veterinary treatment may include:
- stall rest during the acute phase
- intravenous or oral fluid therapy
- monitoring of CK and AST levels
- pain management when appropriate
Early veterinary evaluation is important to prevent complications and guide safe recovery.
Banamine and NSAIDs in Tying Up
Veterinarians sometimes administer non-steroidal anti-inflammatory drugs (NSAIDs) such as flunixin meglumine (Banamine) during acute rhabdomyolysis episodes.
These medications may:
- reduce inflammation
- improve comfort
- support short-term management of acute muscle injury
However, the role of NSAIDs in musculoskeletal healing is complex.
Inflammation is a normal component of tissue repair. During muscle injury, inflammatory signaling activates satellite cells, which are responsible for regenerating damaged muscle fibers.
Experimental research has shown that suppressing inflammatory pathways with NSAIDs may influence aspects of muscle regeneration in some circumstances (Urso, 2013).
This does not mean NSAIDs should never be used. Instead, it highlights the importance of strategic medication use under veterinary supervision, particularly during muscle injury.
Rehabilitation After Tying Up
Recovery after exertional rhabdomyolysis should focus on allowing damaged muscle fibers to heal before returning to full work.
Management commonly includes:
- rest during the acute phase
- maintaining hydration and electrolyte balance
- gradual reintroduction of exercise
- monitoring CK and AST levels during recovery
Returning to work too quickly may increase the risk of recurrence.
Preventing Tying Up in Horses
Prevention strategies focus on managing training consistency, nutrition, and metabolic stress.
Consistent Exercise
Avoid intense exercise after rest days. Horses prone to tying up often benefit from regular, consistent workloads rather than intermittent high-intensity exercise.
Nutritional Management
Many horses prone to exertional rhabdomyolysis benefit from:
- reduced starch intake
- increased fat as an energy source
- balanced vitamin and mineral intake
Electrolyte Balance
Electrolytes support normal muscle metabolism and neuromuscular signaling. Maintaining adequate electrolyte intake is important for horses performing intense work.
Gradual Conditioning
Muscle tissue adapts to mechanical load over time. Sudden increases in training intensity increase the risk of muscle injury.
Progressive conditioning programs help reduce this risk.
Key Takeaways
Tying up is exercise-induced muscle damage, not simply stiffness or soreness.
Successful management requires:
- early recognition of clinical signs
- veterinary evaluation and monitoring
- thoughtful rehabilitation programs
- appropriate training and nutritional management
Understanding how exertional rhabdomyolysis develops helps riders and trainers reduce recurrence risk and support long-term muscular health in performance horses.
FAQ
What causes tying up in horses?
Common causes include sudden increases in workload, high starch diets, electrolyte imbalances, and underlying muscle disorders.
What should you do if a horse ties up?
Stop exercise immediately and contact a veterinarian. The horse should not be forced to walk.
Can tying up be prevented?
Consistent exercise, proper nutrition, and gradual conditioning programs help reduce recurrence risk.
References
Valberg SJ. 2014. Skeletal muscle disorders in horses. Veterinary Clinics of North America: Equine Practice.
Valberg SJ. 2016. Exertional rhabdomyolysis in horses. Equine Veterinary Journal.
Valberg SJ. 2018. Exertional rhabdomyolysis. Equine Veterinary Education.
Urso ML. 2013. Anti-inflammatory interventions and skeletal muscle injury repair. Journal of Applied Physiology.
Author
Dr. Arianna Aaron, DC, IVCA
Founder, Peak Performance International
Equine and Rider Chiropractic Care
Dr. Arianna Aaron is a chiropractor specializing in horse and rider biomechanics and performance optimization. Through Peak Performance International, she works with equine athletes and their riders to improve movement efficiency, address biomechanical restrictions, and support long term soundness and athletic performance.