What is Locking of the Stifle?
The stifle joint has a locking mechanism which is designed to allow the horse to be able to sleep standing up. The stifle is not meant to lock up while the horse is walking or exercising. If your horse is experiencing symptoms such as stumbling, swelling of the limb, or lameness, he should be seen by an equine veterinarian.
Locking of the stifle is a common condition that usually affects young horses. The stifle is similar to the human knee. A locking stifle is also known as upward fixation of the patella (knee cap).
Symptoms of Locking of the Stifle in Horses
Symptoms may include one or more of the following:
- The horse drags his leg
- Locking of the back leg
- The horse stumbles or falls frequently
- Popping noise coming from the leg
- Resistance to canter
- Swelling of the stifle joint
- The horse drags his hind toes during exercise
- Resistance when backing up
- Horse struggles walking up or down hills
- Lameness is more prominent following extended stall rest
- Loss of muscle tone
Causes of Locking of the Stifle in Horses
Causes may include:
- The most common cause of a locking stifle is lack of exercise (the horse is spending too much time being stabled)
- Trauma to the stifle
- Incorrect shoeing
- Osteochondritis dissecans (OCD) lesions
Diagnosis of Locking of the Stifle in Horses
The veterinarian will discuss recent medical history and may ask to see vaccination, dental and deworming records. Let the veterinarian know if your horse has had any recent injuries. The equine’s exercise regimen might need to be discussed. The veterinarian will then perform a full physical exam. The horse’s physical exam may include:
- Listening to his heart, lungs and gastrointestinal tract with a stethoscope
- Blood pressure
- Reflex test
- Palpation of the limbs and muscles
- Checking if the lymph nodes are swollen
- Hoof evaluation
Diagnostic tests may include:
- Complete blood count (CBC) - Checks the count of platelets, red and white blood cells; a CBC will help determine if your horse has a secondary bacterial infection or if he is anemic
- Urinalysis checks for kidney function, crystals, bacteria and blood in the urine
- X-rays of the back two legs
Treatment of Locking of the Stifle in Horses
Treatment for stifle locking in horses will depend on the veterinarian’s diagnosis. If the veterinarian believes that the horse has been confined to a stable for prolonged periods of time, he will recommend that the horse be exercised on a regular basis. Exercise should include walking the horse by hand (not ridden), up and down a hill to strengthen the muscles. Equine aquatic therapy can also help build muscle tone. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to help with inflammation in the ligaments.
An equine hoof specialist (farrier) may need to be called in to trim the horse’s hooves and re-shoe the horse. The farrier may suggest elevating your horse's hind limbs with pads.
If the x-rays showed osteochondritis dissecans (OCD), the veterinarian may recommend performing an arthroscopy to remove any bone fragments. General anesthesia will be required. Osteochondritis is often associated with an imbalance of trace minerals in the horse’s diet. The veterinarian may suggest vitamins and mineral supplements.
Recovery of Locking of the Stifle in Horses
Recovery from stifle locking in horses, particularly when due to lack of exercise, has a good prognosis. It is imperative to follow the veterinarian’s treatment plan. Your horse will need daily exercise to build up his muscles. Follow-up visits will be required to monitor the horse’s progress.
If your horse underwent surgery, the equine surgeon will give you a postoperative treatment plan. The surgeon will give you instructions on how to keep the incision clean and how to re-bandage the area. The veterinarian may prescribe anti-inflammatory and pain medication. Antibiotics may also be prescribed as a preventative against a bacterial infection. The horse will be on limited exercise for 3 to 4 weeks.
Surgical procedures sometimes have postoperative complications. Contact your veterinarian if you observe:
- Bleeding from the incision
- Open sutures
- Labored breathing
- Incision has a foul smell
- Redness or swelling of the incision
Full recovery from surgery may take several months. Follow up visits will be required to remove sutures and to check on the horse’s progress. The veterinarian may recommend taking new x-rays. A complete blood count may also be recommended to rule out a bacterial infection. Recovery of locking of the stifle due to osteochondritis dissecans has a good prognosis as well.