Mrs. Smith often took her poodle Louise out for walks by my home, and on those occasions I couldn’t help but notice Louise’s characteristic gait. On some days, Louise seemed to get along fine with a jaunty hitch in her stride, but on others, she limped.
“It comes and goes, but she’s worse lately, especially after running around,” Mrs. Smith explained when she brought Louise into our hospital. At thirteen months old, Louise was a well-cared-for youngster in otherwise excellent health. Mrs. Smith gushed, “Louise is such a happy little dog. I can tell when she’s especially joyful because she does a little skip with her hind legs.”
I examined Louise methodically from nose to tail. At her right hind leg I found what I had suspected all along: Louise’s kneecap was loose, allowing me to easily move it out of place. What Mrs. Smith had interpreted as happy-go-lucky skipping was actually a symptom of a congenital musculoskeletal problem common in small-breed dogs. It’s called medial patellar luxation (MLP), or slipped knee cap.
I asked one of our veterinary technicians to take a series of radiographs (x-rays) of Louise’s hips and knees. Once the films were ready, I showed Mrs. Smith how Louise’s right kneecap was displaced medially, or towards the center. The radiographs also verified that her hips and other knee appeared to be fine.
In small-breed dogs, MLP is a common finding where the patella luxates, or dislocates. It is usually a congenital structural defect where the angles of the bones and tendon insertions are not as stable as they should be. Classically, the dog intermittently hikes a back leg up into a flexed position for a few steps when the kneecap slips out of place. Then, when the kneecap pops back into position, the gait returns to normal. The severity of the kneecap displacement is graded from I to IV, with grade IV being the most severe. Louise’s knee was a solid grade III.
Very small, lightweight dogs may do well with no treatment if they are not showing signs of discomfort or soreness. However, surgery is the only way to fix the knee of a dog who is showing consistent pain, as the kneecap’s abnormal tracking will ultimately result in degenerative joint disease. Without surgery, a lame dog with MLP faces a lifetime of non-steroidal anti-inflammatory drugs and worsening degeneration of the joint.
A board-certified veterinary surgeon performed Louise’s surgery. She recovered in the hospital for a day, then went home sporting a big padded bandage on her leg, along with a bag full of pharmaceuticals to keep her comfortable. A week later at her suture removal, Mrs. Smith sighed at the prospect of having to keep the energetic Louise on only strict leash walks for another five weeks while things healed. However, after a course of physical therapy, Louise and Mrs. Smith were once again a regular sight in the neighborhood, only now Louise’s prance of joy was for real.
Dr. Deirdre Brandes is a veterinarian at the Rancho Santa Fe Veterinary Hospital, open at the Helen Woodward Animal Center. She can be reached at www.rsfvets.com, or 858-759-8797.