Stringhalt is a neuromuscular condition in horses characterized by exaggerated, involuntary flexion of one or both hind legs during movement. Often noticeable at the walk, this condition can cause varying degrees of discomfort and impact a horse’s ability to perform. While it is not typically life-threatening, understanding stringhalt is crucial for managing affected horses and improving their quality of life.
This comprehensive guide covers the causes, symptoms, diagnosis, treatment options, and preventative measures for stringhalt in horses.
What is Stringhalt?
Stringhalt is a disorder that affects the peripheral nerves and muscles responsible for leg movement. Horses with stringhalt display an abnormal gait marked by sudden, exaggerated upward flexion of one or both hind limbs.
Types of Stringhalt
There are two main types of stringhalt:
- Classic Stringhalt:
- Occurs sporadically and is usually caused by nerve or muscle damage.
- Often affects only one leg, although both legs may be involved in some cases.
- Australian (or Bilateral) Stringhalt:
- A more severe form that often affects both hind legs.
- Commonly linked to exposure to toxic plants such as Hypochaeris radicata (commonly called flatweed or false dandelion).
Causes of Stringhalt
The exact cause of stringhalt can vary, but the condition is generally linked to damage or dysfunction of the peripheral nerves controlling the hind legs. Below are the primary factors associated with stringhalt:
1. Nerve Damage
- Injury or trauma to the hind limbs or back can damage the peripheral nerves, leading to abnormal muscle contractions.
2. Toxic Plants
- Ingestion of certain plants, such as flatweed, is associated with Australian stringhalt. These plants contain toxins that affect the nervous system.
3. Trauma or Scar Tissue
- Injury to the tendons or muscles of the hind legs may result in the formation of scar tissue, which disrupts normal movement.
4. Neurological Disorders
- Stringhalt may sometimes be linked to underlying neurological conditions affecting motor control.
5. Idiopathic Causes
- In some cases, the cause of stringhalt cannot be determined, and it is classified as idiopathic.
Symptoms of Stringhalt
The hallmark symptom of stringhalt is an exaggerated flexion of one or both hind limbs during movement. This symptom can vary in severity and may be accompanied by other clinical signs.
Primary Symptoms:
- Exaggerated Gait: A sudden, jerky upward movement of the hind leg(s), often described as a “snapping” motion.
- Asymmetry: Classic stringhalt typically affects only one hind leg, while Australian stringhalt often affects both.
- Difficulty Walking: Severe cases may cause significant coordination issues, leading to stumbling or an inability to walk normally.
Additional Symptoms:
- Muscle Atrophy: Prolonged stringhalt may result in muscle wasting in the affected hindquarters.
- Reduced Performance: Affected horses may struggle with activities requiring precise movements, such as jumping, dressage, or trail riding.
- Pain or Discomfort: In some cases, horses may exhibit signs of discomfort when moving.
Diagnosing Stringhalt
Diagnosis of stringhalt involves a combination of clinical observation, physical examination, and diagnostic tests to rule out other conditions with similar symptoms.
Diagnostic Steps:
- Observation of Gait:
- The veterinarian will observe the horse walking and trotting to assess the degree of hind limb flexion and identify whether one or both legs are affected.
- Physical Examination:
- A thorough examination of the hind legs to check for injuries, swelling, or pain that could contribute to abnormal movement.
- Neurological Assessment:
- Tests to evaluate the horse’s reflexes, muscle tone, and coordination can help determine if a neurological issue is present.
- Ultrasound or X-rays:
- Imaging may be used to check for underlying issues such as tendon injuries, joint abnormalities, or scar tissue.
- Blood Tests:
- In cases of suspected Australian stringhalt, blood tests can identify exposure to toxic plants or other potential toxins.
Treatment Options for Stringhalt
The treatment for stringhalt depends on its severity and underlying cause. While some cases resolve on their own, others may require medical intervention or surgical procedures.
1. Rest and Rehabilitation
- Mild cases of stringhalt may improve with rest and controlled exercise to allow nerves and muscles to recover.
2. Surgical Intervention
- In severe cases, a procedure called a tenectomy (cutting of the lateral digital extensor tendon) may be performed to alleviate symptoms.
- Surgery is most commonly used for classic stringhalt and is often successful in reducing the exaggerated gait.
3. Toxin Removal
- If stringhalt is caused by exposure to toxic plants, removing the horse from the contaminated pasture is critical.
- Supportive care, including dietary adjustments, may aid recovery.
4. Medications
- Anti-inflammatory drugs or muscle relaxants may be prescribed to reduce discomfort and muscle spasms.
5. Physical Therapy
- Stretching and strengthening exercises can improve muscle tone and flexibility in affected horses.
- Massage and chiropractic care may also help alleviate symptoms.
Prognosis for Stringhalt
The prognosis for horses with stringhalt depends on the severity of the condition and the underlying cause:
- Mild Cases: Many horses recover fully with rest and proper management.
- Severe Cases: Horses requiring surgery often show significant improvement, but some residual gait abnormalities may persist.
- Chronic or Bilateral Stringhalt: Horses with Australian stringhalt may take months to recover fully after toxin removal, and some may experience permanent effects.
Preventing Stringhalt
While it is not always possible to prevent stringhalt, certain measures can reduce the risk:
1. Pasture Management
- Regularly inspect pastures for toxic plants such as flatweed, and remove them promptly.
- Rotate grazing areas to avoid overgrazing and exposure to potentially harmful plants.
2. Hoof and Leg Care
- Maintain regular farrier visits to ensure healthy hooves and avoid unnecessary stress on the legs.
- Address injuries or trauma to the hind limbs promptly to minimize the risk of nerve damage.
3. Nutrition and Supplements
- Provide a balanced diet to support overall nerve and muscle health.
- Supplements such as magnesium or vitamin E may support neuromuscular function in horses prone to stringhalt.
4. Routine Monitoring
- Regularly observe your horse’s gait and behavior to detect any early signs of stringhalt or other lameness issues.
When to Call a Vet
Contact your veterinarian if your horse displays:
- Sudden, exaggerated hind limb movements.
- Signs of pain, discomfort, or difficulty walking.
- Exposure to toxic plants or unfamiliar grazing areas.
Conclusion
Stringhalt in horses is a complex condition that can significantly impact a horse’s mobility and quality of life. By understanding its causes, recognizing symptoms early, and pursuing appropriate treatment, horse owners can help their equine companions manage or recover from this condition.
Preventative measures such as pasture management, routine care, and monitoring are crucial in reducing the risk of stringhalt and supporting overall hoof and leg health. With proper attention and care, most horses can lead comfortable, active lives even if affected by stringhalt.
