What is Patellar Luxation?
You may have noticed that horses have the ability to stand up for a long period of time. They are able to do this because they can lock their knee (patella) in position, which uses less energy and muscle. If your horse has persistent patellar luxation, the patella is unable to be unlocked and the leg stays stiff and unable to bend back to normal position. There are four different grades of patellar luxation, which vary from mild fixation of the patella to the inability to unlock the patella even with help.
Patellar luxation (floating patella or upward fixation of the patella) is an uncommon condition in foals that is caused by a recessive gene, but adult horses can also develop this condition due to injury or other trauma. There are several forms, which include unilateral, bilateral, intermittent, and persistent. There are also four grades of severity. The problem may be so severe in some foals that they are not able to stand up straight due to not being able to straighten the leg. This can be a serious and debilitating condition for your horse that will affect their ability to walk or even to stand.
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Symptoms of Patellar Luxation in Horses
The symptoms of patellar luxation depend on which type your horse is suffering from. The most commonly reported signs include:
- Hind leg lameness
- Dragging toes during exercise
- Resistance to canter (would rather trot)
- Throwing head back to avoid cantering
- Avoiding limb extension in the affected leg
- Difficult or resisting going uphill or downhill
- Refusal to or unable to back up
- Worst when your horse first starts moving
- Loss of muscle tone in that leg
There are four types of patellar luxation and four different grades of severity, which include:
- Unilateral only affects one leg
- Bilateral affects both legs
- Intermittent luxation is not permanent and only happens during certain exercise
- Persistent luxation is a permanent condition that is unable to be reduced manually
- Grade I is able to be manually reduced, but goes back when released
- Grade II patellar luxation frequently locks up and the leg is often carried in an unusual position but it can still be manually reduced
- Grade III patellar luxation is permanent and causes tibia torsion and is semi-flexed
- Grade IV patellar luxation is permanent, the tibia is twisted, and the crest is deviated a great deal with the leg unable to be used properly
Causes of Patellar Luxation in Horses
The causes of patellar luxation vary, but the most common are:
- Chondromalacia, which is when the cartilage becomes soft from repeated injuries
- Damage to the interior or cruciate ligament
- Frequent microtrauma of the bones
- Damage to the meniscal cartilage
- Lesions from osteochondritis dissecans
- Not enough exercise
Diagnosis of Patellar Luxation in Horses
To get a proper diagnosis of your horse, a visit with an equine veterinarian is necessary. Some veterinarians will come to you rather than having you bring your horse to them. Determining whether your horse has patellar luxation will include the veterinarian obtaining a medical background, immunization records, type of work your horse does, and a description of any abnormal behavior you have noticed. Also, be sure to tell the veterinarian if your horse is on any kind of medication. A physical examination will be done, including an assessment of your horse’s conformation, behavior, and attitude.
Following this, the veterinarian will record your horse’s blood pressure, temperature, body condition, capillary refill time, mucous membrane color, heart rate, respirations, lung sounds, height, weight, and reflexes. Your veterinarian may also do a lameness examination to determine how badly the patellar luxation is affecting your horse. In addition, x-rays of the affected areas will be performed to get a good look at the bone structure. If more detail is needed, a CT scan, MRI, ultrasound, or body scan may be done.
Treatment of Patellar Luxation in Horses
The typical treatment for patellar luxation is medication, special shoes, and physical therapy although the more serious grades may need surgical repair.
Grade I and II
Grade I treatment usually includes medication for pain (NSAIDS), antibiotics, and stall rest.
Grade III and IV
These grades of injury usually need surgery, but medical treatment will be tried first. The surgery is done while your horse is under anesthesia and in a standing position. Medial patellar luxation is the treatment that should be used for severe cases such as with grade III and IV. This is done while being guided by an ultrasound to prevent damage.
Recovery of Patellar Luxation in Horses
No matter which type of patellar luxation your horse has, it is important to get treatment right away and make sure you follow the veterinarian’s instructions. The return to exercise will be carefully dictated, adherence is essential for a timely recovery. Follow up with the veterinarian on a consistent basis, bringing your horse back for check-ups as advised.