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      Understanding Stifle Injury in Horses: Causes, Treatment, and Prevention

      The stifle joint in horses is essential for the proper functioning of their body, and it can be easily affected by a variety of injuries, lameness and other disorders. In this article, we will explore the anatomy of the stifle joint, discussing the differences between horse stifles and human knees, types of stifle disorders, signs and symptoms of the injury, causes, risk factors, diagnosis, treatment and prevention.

      We will look at the impact of diet, supplements available to support joint health and ways to reduce the risk of stifling injury such as through exercise and tailoring a balanced diet.

      Finally, we will explore the implications of stifle injury in horses, including potential consequences and understanding the elements that influence the horse’s recovery.

      Quick Summary

      • The stifle joint of horses is composed of multiple structures that provide stability and mobility while supporting the horse’s weight.
      • Stifle injuries in horses are typically caused by repetitive stress or traumatic injury, and can be difficult to detect due to the absence of definitive symptoms.
      • Preventive measures should be taken to reduce the risk of stifle injury in horses, such as providing regular exercise, maintaining a healthy weight, ensuring appropriate shoeing, and providing essential nutrients and dietary supplements.

      Anatomy of the Stifle Joint


      Image of a horse with stifle lameness


      The stifle joint in horses is the largest joint in the body, designed for flexion and extension of the hind leg. It is made up of a complex structure of muscles and ligaments that are responsible for the stability and mobility of the joint. The stifle joint is comprised of the femur, tibia, patella, menisci, and ligaments, including the three patellar ligaments, medial patellar ligament, and collateral ligaments. The femur, tibia, and patella form the articulation of the stifle, while the menisci and ligaments provide stability and reduce friction during movement.

      The stifle joint plays an important role in shock absorption, as well as supporting the horse’s weight. The menisci evenly distribute the weight across the joint, while the ligaments work to secure the joint in place. The anterior and posterior cruciate ligaments (ACL and PCL) are responsible for providing joint stability, while the stay apparatus utilizes the stifle joint to provide support when the horse is standing.

      In addition to supporting the horse’s weight, the stifle joint also allows for smooth movement of the joint as it flexes. This has been the impetus for the heightened focus on equine stifles, as recent developments in imaging technology have enabled more accurate diagnosis and treatment of stifle-related issues.

      Stifle vs. Human Knee


      Image of human knee compared to stifle joint of a horse

      Image source:


      The stifle joint in horses is comparable to the knee joint of humans. Both joints play a similar role and enable motion of the leg. The equine stifle is angled differently than its human equivalent, making it less susceptible to cruciate ligament ruptures, a common injury in human and canine knees. This is due to the angle of the stifle joint and the manner in which the horse’s weight is distributed, unlike humans. The options for animals with severe cruciate ligament ruptures are limited. Joint blocks, corrective shoeing, and other treatments may be employed to help the animal recover, but the prognosis may still be poor.

      In addition to the angle of the stifle joint, the patella ligaments, which are necessary for the stability of the stifle, are longer in horses than in humans. This lengthening of the patella ligaments helps to lessen the amount of lameness and injury horses experience. While human knee injuries often involve meniscal injuries, or tears in the cartilage, horses rarely experience this type of injury. This is due to the unique shape and arrangement of the patellar ligaments and the medial femorotibial joints in the horse’s stifle.

      Types of Stifle Disorders

      The stifle joint, which is the joint between the femur and tibia bones in the hind leg of horses, can be affected by a variety of conditions. These include arthritis, bone cysts, meniscal tears and ligament injuries, which can be caused by repetitive stress, trauma, excessive use, changes in direction and rapid movements.

      Upward Fixation of the patella is a common stifle disorder that is often seen in young horses and is sometimes referred to as “sticky stifles” or “catchy stifles”. This condition is characterized by the stifle joint locking and keeping the leg in a fixed position.

      In order to avoid upward fixation of the patella, it is important to strengthen the muscles and ligaments through regular exercise. This can help to reduce the risk of the condition occurring, as well as helping to keep the stifle joint strong and healthy.

      Additionally, it is important to have a good diet and supplement plan for your horse to ensure that their joints are receiving the nutrients they need to remain healthy and strong.

      Signs and Symptoms of Stifle Injury

      Stifle injury is a condition that affects the stifle joint in horses, leading to lameness and discomfort. It is of paramount importance to identify it in its early stages, as timely intervention can prevent the condition from deteriorating and causing long-term damage.

      Signs of a stifle injury in horses may be difficult to detect, such as a reluctance to work, soreness in the back or croup, and clicking noises. Additionally, lameness in the hind end, swelling, inflammation, and developmental issues may be present. Stifle injuries can be difficult to detect due to the lack of a definitive indicator such as a head bob or limp.

      Furthermore, stifle lameness can be difficult to pinpoint, especially when the stifle is not swollen, making it necessary to eliminate potential causes to determine the underlying issue. Audible clicking noises emanating from a horse’s stifle region may be indicative of a rupture in the cartilage or ligaments of the joint.

      Causes of Stifle Injury

      The stifle joint is the largest joint in the horse’s body, located between the femur and the tibia and analogous to the human knee joint. Stifle injuries in horses are typically the result of repetitive stress on the joint or a traumatic injury, often stemming from rapid changes in direction or sudden deceleration. In rare cases, a stifle injury may be caused by developmental issues.

      Repetitive stress can have a detrimental effect on the stifle joint, as it can lead to the gradual wearing down of cartilage and soft tissues, resulting in inflammation and pain. Trauma to the stifle joint can result in damage to the bones, cartilage, ligaments, or tendons. Certain developmental issues, such as subchondral bone cysts, patellar laxity, and osteochondritis dissecans, can potentially lead to stifle injury.


      a horse with s stifle injury with a persons hand on the stifle

      Risk Factors for Stifle Injuries

      Stifle injuries in horses are caused by a variety of factors, including trauma, overuse, and sudden changes in direction. Certain activities, such as jumping and barrel racing, may also increase the likelihood of these injuries. Equines that participate in sports such as showjumping, 3-day eventing or barrel racing are more susceptible to such injuries. Nevertheless, any horse of any age can be affected by stifle injuries.

      Stifle injuries are more likely to occur in disciplines that involve abrupt stops, abrupt changes in direction, and high speeds. In addition, straight hind limbs and hooves with low heels and long toes can increase the risk of stifle injuries in horses. Jumping, barrel racing, and other activities that involve sudden stops, quick direction changes, or high speeds are disciplines that may increase the risk of stifle injuries in horses.

      Therefore, horse owners should be aware of the potential risk factors associated with stifle injuries and take steps to reduce the chances of their horse suffering from a stifle injury.

      Diagnosing Stifle Injury

      Accurately diagnosing stifle injury in horses is essential for preventing further damage and ensuring the most effective treatment plan. The initial assessment of a potential stifle injury should commence with a visual examination.

      The diagnosis of stifle injury typically involves the assessment of swelling, flexion testing, joint blocking, and the utilization of imaging technologies such as X-ray and ultrasound. An ultrasound can provide insight into the presence of ligament or muscle damage associated with a stifle injury, while X-rays can provide insight into the presence of arthritis, bone cysts, or fractures associated with a stifle injury.

      The use of imaging technologies is a crucial step in accurately diagnosing stifle injury. The ability to identify abnormalities in the stifle joint can allow for the development of the most effective treatment plan and avoid the potential for further damage.

      It is important to note that the use of imaging technologies should be combined with the assessment of clinical signs and the results of flexion tests in order to ensure an accurate diagnosis.


      Rest is the most essential remedy for stifle injuries in horses. To reduce inflammation and provide relief for stifle injuries in horses, anti-inflammatory medication may be prescribed. Stifle injections can also be used to reduce pain and inflammation, although there are associated risks.

      Arthroscopy is a minimally invasive technique that is used for both diagnostic and therapeutic purposes, while Desmotomy is a surgical procedure in which the medial patellar ligament is cut and is utilized when more conservative treatments are ineffective.

      A variety of additional treatments can be used to address stifle injuries in horses, such as laser therapy, hydrotherapy, equine acupuncture, estrogen, interleukin-1 receptor antagonist protein, platelet-rich plasma therapy, and stem cell treatments. It is important to develop a customized treatment plan for each case that is tailored to the individual horse’s needs.

      This plan should include a combination of rest, anti-inflammatory medications, and other treatments such as physical therapy and, if necessary, surgery. A controlled exercise program should also be implemented to maintain muscle strength and joint flexibility.


      Activo-Med Water Treadmill


      A study revealed that 40% of 82 Western performance horses that underwent arthroscopic stifle surgery were able to return to their intended use. It is important to recognize that the success rate of a horse returning to its intended use after stifle surgery can vary depending on the severity of the injury, the diagnosis and treatment, the clinical signs, and any other radiograph results.

      The factors that can influence the probability of a horse regaining its intended use following stifle surgery include the severity of the injury, the diagnosis and treatment, the clinical signs, and the radiograph results. In severe cases, the prognosis may be poor, as the injury may be too severe for the horse to regain its original intended use.

      Additionally, if the diagnosis is incorrect or the treatment is inadequate, the prognosis may be less favorable. Furthermore, if the clinical signs are severe, it is likely that the horse may not be able to return to its intended use.

      Preventing Stifle Injury

      Stifle injury can cause significant pain and disability in horses, and if left untreated, can result in long-term lameness. Therefore, it is essential to take preventive measures in order to avoid such injuries. Exercises such as walking and trotting in straight lines and over ground poles, riding over raised poles (cavaletti), and the hold-and-release exercise, where the horse is asked to brace against a pull for 10 seconds before the pull is released, can all be beneficial in reducing the risk of stifle injury.

      The hold-and-release exercise helps to strengthen the back, abdominal, and quadriceps muscles, thus reducing the risk of stifle injury. In addition to providing regular exercise, it is essential to maintain a healthy weight for the horse, ensure appropriate shoeing, and avoid over-exerting the animal.

      This will help to reduce the risk of stifle injury, as well as ensure that the horse is not put in a position where such injury may occur.

      Supporting Joint Health through Diet

      Nutrition plays an important role in maintaining joint health in horses, and a well-balanced diet tailored to the individual horse is essential for optimal joint health. For example, omega-3 fatty acids, vitamins, and minerals such as calcium, phosphorus, vitamin C, and vitamin E are all essential for maintaining joint health in horses.

      Is Your Horse’s Diet Missing Anything?

      A balanced diet for horses is essential for ensuring optimal health, preventing the onset of diseases, and optimizing performance. A horse’s diet should include essential nutrients such as protein, carbohydrates, fats, vitamins, minerals, and water in order to ensure optimal health. To identify any dietary deficiencies in a horse, it is necessary to analyze the current diet, taking into account the horse’s age, breed, and activity level, as well as consulting with a qualified veterinarian or equine nutritionist.

      Horses may benefit from dietary supplements such as vitamins A, B, C, D, E, and K, minerals, probiotics, and cod liver oil. Younger horses, in particular, may be at greater risk of nutritional deficiency due to their more rapid growth and development. Thus, it is important to carefully monitor the diet of younger horses to ensure that they are receiving the correct balance of nutrients for their age, breed, and activity level.

      Locking Stifle in Horses

      Locking stifle also known as Upward Fixation of the Patella (UFP) is a condition in horses where the stifle becomes locked into position and unable to move out of the ridge on the end of the horse’s femur. Horses exhibiting locking stifles may demonstrate shorter strides and a clicking sound, commonly referred to as ‘clicking stifles’.

      Locking stifle is commonly attributed to conformation issues in certain horses, as well as rapid growth or inadequate body condition in younger horses. X-rays are commonly used to diagnose locking stifle in horses, allowing for the exclusion of other potential causes such as fractures, foot abscesses, or stringhalts.

      Treatment options for a locked stifle in horses can range from a tailored exercise program and supplementation to a more invasive surgical procedure known as Medial Patella Desmotomy. This procedure requires sedation and carries a certain degree of risk.

      Supplements for Horses Stifle Injury

      Supplements can be an effective tool in the prevention and treatment of stifle injuries in horses, as they can help support joint health and reduce inflammation. Studies have shown that supplements containing glucosamine, MSM, Chondroitin, hyaluronic acid and omega-3 are effective in the prevention and treatment of stifle injuries in horses. Glucosamine has been demonstrated to provide pain relief, reduce tenderness, and enhance mobility in horses with stifle injuries. MSM has been shown to be effective in reducing inflammation and improving joint mobility in horses with stifle injuries. Chondroitin has been shown to be beneficial in reducing inflammation and improving joint mobility in horses with stifle injuries. Hyaluronic acid has been shown to be effective in providing lubrication to joints and reducing inflammation in horses suffering from stifle injuries. Supplementing a horse’s diet with omega-3 has been shown to reduce inflammation and improve joint mobility, making it beneficial for horses suffering from stifle injuries.

      The most common ingredients found in joint supplements for horses include MSM, hyaluronic acid, and omega-3 fatty acids. Joint supplements are important for horses of any age, but they may be especially beneficial for young horses who are more prone to stifle lameness and meniscal injuries. Additionally, joint supplements can help to avoid stifle injuries in younger horses, which can often lead to severe lameness or even permanent damage to the horse’s stifle.

      Final Thoughts

      Stifle injury in horses is a complicated and often painful condition that can be difficult to diagnose. It is typically caused by repetitive stress or traumatic injury, but can also result from developmental issues. Horse owners should be aware of the predisposing risk factors such as trauma, overuse, jumping, barrel racing and other activities involving abrupt stops and direction changes, in order to reduce their horse’s chance of suffering from a stifle injury.

      In order to properly diagnose a stifle injury, accurate assessments need to involve clinical signs, flexion tests, joint blocking, and imaging techniques. The prognosis for a horse to return to its intended use after stifle surgery depends on a variety of factors including the severity of the injury and the treatment administered.

      A comprehensive treatment plan should be implemented and preventive measures taken to reduce the risk of stifle injury in horses. This includes providing regular exercise, maintaining a healthy weight, ensuring appropriate shoeing and avoiding over-exertion. Additionally, a well-balanced diet tailored to the individual horse, along with joint supplements, can help reduce inflammation and support joint health.

      Overall, understanding and recognizing signs of stifle injuries is important for successful treatment and prevention. Equipping owners with the knowledge necessary to identify, address and prevent stifle injury can provide relief to horses and peace of mind to their owners.

      Popular Questions

      Can a horse recover from a stifle injury?

      Based on standard advice for stifle injuries, it is clear that a horse can recover from a stifle injury with rest and medication.

      However, the severity of the injury will dictate the extent of recovery time needed.

      How do I know if my horse has a stifle injury?

      To determine if your horse has a stifle injury, be sure to look for signs of lameness, anxiety, and general tenderness in the affected area.

      Your veterinarian may also use digital x-rays, ultrasound, and curvilinear ultrasound probes to examine the joint and make an accurate diagnosis.

      What are common stifle problems in horses?

      Common stifle problems in horses include soft tissue, bone and cartilage disorders, as well as fractures, gonitis, dislocation and bone cysts.

      High-impact activities such as jumping and barrel racing increase the risk of developing stifle injuries due to their repetitive stress, trauma, excessive use, changes in direction and rapid deceleration.

      How do you exercise a horse with a stifle problem?

      When exercising a horse with a stifle problem, it is important to begin with passive stretching and strengthen the limb with gentle exercises such as walking, trotting, polework, and tail pulls to the side.

      Gradually progress to more advanced exercises such as cavaletti, cold hosing, and NSAIDs to further aid rehabilitation.

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