Patellar luxation in dogs is typically a short-lived, but very painful, incident. Although it is not a life-threatening medical condition, the pain of patellar luxation is very real for dogs, and this often prompts dog owners to seek medical therapy. The important thing is that dog owners are able to recognize the symptoms of patellar luxation so that they can limit the dog’s recurrence of pain and consider medical treatment options.
Patellar Luxation Explained
The patella is the anatomical term for the knee cap. Under normal conditions, a dog’s patella can sit snuggly within the confines of the femur (thigh bone) because of femoral grooves which hold it in place. These grooves are located on both sides of the patella and allow for the movement of the patella when the knee joint is bent, therefore allowing the use of the quadriceps muscles as well. Joint fluid within the knee keeps the patella lubricated so that there is free-flowing movement of the knee.
Patellar luxation occurs when the patella slips from the femoral groove, causing bone-on-bone friction between the patella and the grooves of the femur. This bone-on-bone friction is what causes such immense pain for dogs. Once the patella has luxated away from the groove, it cannot return to the groove until the quadriceps muscles relax and allow for this movement. While the patella remains luxated, the knee joint actually locks and immobilizes the dog’s leg.
Genetic Predisposition
Some dog breeds appear to be genetically predisposed to patellar luxation, including the Pekingese, Poodle, Lhasa Apso and Pomeranian. Dogs of these breeds should be checked for patellar luxation prior to being bred.
Signs and Symptoms of Patellar Luxation
The symptoms of patellar luxation in dogs are typically very noticeable, although they may seem somewhat strange. As the patella luxates and crosses the femoral groove, the dog is caught with an intense, momentary sensation of extreme pain. Once the luxation is complete, however, the dog is no longer in pain. Yet, the dog will still be unable to move its leg until the quadriceps can relax long enough for the patella to return to normal position. This time period can last anywhere from 10 minutes to several days, depending on how long it takes that muscle to relax.
Even prior to the luxated patella returning to its normal position, most dogs can still take part in normal activities. The only difference is that they may be walking with a three-legged limp or completely elevating their hindquarters from the ground and walking on their front legs.
Patellar Luxation Diagnosis and Treatment
Diagnosing patellar luxation is relatively easy based on the symptoms alone. However, physical examination is not enough to conclusively diagnose patellar luxation because of other etiologies could produce similar symptoms. In general, an x-ray should be done at the time of the luxation so that it can be viewed radiographically.
Surgery is the only true method which can correct patellar luxation in dogs, although surgery is not always necessary in every case. If the episodes are somewhat rare and resolve within a few minutes, the risks of surgical correction may be greater than the benefits. However, if patellar luxation causes regular pain for the dog, surgery will usually need to be considered.