Interestingly enough, I’ve noticed in all of my history with veterinary medicine both as a student and as a doctor, that cases tend to appear in pairs or multiples.
Very often, I find myself dealing in the same week with three blocked cats, or two snake bites for example. This phenomenon has no logical explanation, but somehow it is just like that. Lately I got visited by few limping dogs that later were confirmed to suffer from the same problem in their knee. This particular knee abnormality is called Patellar luxation.
The patella is the knee cap. It is situated between the two long bones of the back leg, the Femur and the Tibia. In normal leg anatomy the patella is situated in a special groove in the femur (the thigh bone), attached to the two long bones by tendons and muscle. The Patella’s location in the femur groove allows normal gliding motion in flexion and extension of the knee joint.
Patellar luxation is a condition in which the patella jumps out of the groove sideways when the knee is bent. This causes the leg to “lock up” with the paw up in the air.
The condition has four grades of severity. In grade 1 the patella is normally in the femoral groove but can be manually manipulated outside of the groove. The 2nd and 3rd grades are the most common, in which the patella intermittently slides outside of the groove. In the most severe 4th grade the patella is permanently situated outside of the groove.
Patellar luxation is the most common congenital abnormality in dogs, affecting about 7% of puppies. Small breeds are most commonly affected especially Boston terriers, Chihuahuas, Pomeranians, Miniature poodles,and Yorkshire terriers. The incidence in large breed dogs has been in rise over the last 10 years.
Beside being a congenital abnormality, patellar luxation can also be caused in a normal dogs as a result of a traumatic injury.
The most common sign associated with the condition is limping. The duration and the severity of the limping depends on the grade of the condition. The more severe the condition is, the more frequent the limping episodes are. In a typical patellar luxation case the limping will be intermittent(on again- off again) and will be resolved spontaneously, sometimes after only few minutes.
The diagnosis of the condition is done by a manual manipulation of the joint. X ray exam can confirm the presence of the patella outside of its normal groove.
Unfortunately conservative treatment has little to offer, and the best permanent treatment for patellar luxation is by a corrective surgery.
Over time, if stays untreated the condition worsen,s severe arthritis develops which may lead to permanent damage and compromise mobility.
If your dog shows signs of permanent or intermittent episodes of limping on his back leg, along with yelping and signs of discomfort take it to be checked by your vet.
Early treatment of patellar luxation can yield a long, happy and pain free life for your dog. Ask your vet to assess your dog’s knee condition to make sure your dog does not have a knee problem.
Dr. Moshe Oz operates the Rose Valley Veterinary Hospital in West Kelowna, 2476 Westlake Rd.