Q: We recently adopted a young adult Yorkshire terrier named Sally. She seems fine, but the veterinarian recognized that her kneecaps dislocate and then pop back into place. What should we watch for? How will we know if she needs surgery?
A: Dislocation of the kneecap, or patellar luxation (PL), can occur in any dog, but it is most common in small-breed dogs. In about half of all dogs with PL, both kneecaps luxate.
In most cases, the condition is inherited, although it also can be caused by an injury. Affected dogs have several structural abnormalities of the hind leg(s), including an excessively shallow groove where the patella sits.
In dogs with mild PL, the kneecap is stable during normal walking or running, and the condition is only discovered during a veterinary exam. In dogs with moderate PL, the kneecap dislocates, or slips out of its groove, and then pops back into place on its own. Dogs with more severe PL have chronically dislocated kneecaps that may cause frequent or continuous lameness and pain.
You’ll know the kneecap is dislocated if, when playing normally, Sally suddenly holds up one hind leg and runs on three legs. Then, just as suddenly, the kneecap pops back into its usual position and Sally runs normally on all four legs again.
If one or both of her kneecaps dislocates frequently or she limps or shows other signs of pain, she will need pain medicine and perhaps also physical therapy and/or surgery to repair the affected knee(s).
To minimize problems, keep Sally slim. Improve her traction on smooth floors by trimming her nails often and making sure the fur between her pads is clipped short.
Lee Pickett, V.M.D. practices companion animal medicine in Pennsylvania. Contact her at firstname.lastname@example.org.
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