Beagle probably has dislocating knee cap

5/25/2014

Dear Dr. Thompson: I have a small beagle that is a year old. For the last two to three months after she sleeps, her right leg hangs in the air for a few minutes and then it will drop down. Our veterinarian checked her out but didn’t find anything wrong. I was told if it continues X-rays would be the next step. It continued to happen so he took a couple of X-rays and couldn’t find anything wrong. Is there such a thing as her leg just going to sleep? I’ve tried fish oil with no change. What more can I do?

It is not likely that her leg is falling asleep but rather she probably has a dislocating knee cap. The technical term is a patellar luxation and it is a very common problem in toy breed dogs and I do see it frequently in beagles. She is holding her leg up when the knee cap pops out of the groove. This is not unusual when she gets up or down.

Patellar luxation is a congenital condition in many breeds of dogs that begins to result in symptoms around one year of age. The muscles of the front part of the thigh all come together to form the tendon that the knee cap is imbedded within and attaches to the upper part of the tibia or shin. As she has grown the alignment of the tibia is abnormally curved to the inside and this puts pressure on the knee cap to pop out of the groove in the femur it normally glides through when the knee is flexed and extended. She holds her leg up when it pops out as a result of the pain and abnormal position.

Patellar luxations are graded on a scale of one to four with one being the least severe. A grade one patellar luxation only pops out occasionally and does not result in any significant limping. The higher the grade the more severe the alignment problem and loss of function.

Generally, a grade two or higher patellar luxation requires surgery to correct the problem. This involves deepening the groove the knee cap slides though, tightening the ligaments on the side, and moving the attachment of the tendon over to correct for the misalignment. The most severe cases may require correction of the femur or tibia as well, but this is rare.

With surgery most dogs will have significantly improved function and pain-free use of the leg. Diagnosis of lower grade luxations can be difficult since there are rarely any changes on an X-ray and your veterinarian would have to manually pop the knee cap out, which can be difficult with a grade one luxation.

If she is only occasionally having trouble consistent with what would be a grade one luxation, no treatment would be needed at this point. However, you should be aware that if her symptoms are more frequent or she limps regularly it is a sign the dislocations may need treatment. Good luck.

Questions for Dr. Gary Thompson can be emailed to askthevet@theblade.com or mailed to The Blade, Attn. Ask the Vet, 541 N. Superior St., Toledo, OH 43660. Dr. Thompson regrets that he cannot answer individual letters.