[thedoc (OP)]

Why do Jack Russell dogs sometimes run on three legs with a hind leg lifted?
Asked by Tom, Stowmarket

                                          Hear this Question on our Podcast

[thedoc (OP)]

This one has stumped the Naked Scientists team - we really don't know!  Do you have any idea why this may be?  If so, let us know!

[Sandi]

Many small dogs have a condition called "luxating patellas" meaning the kneecap partially or completely slips out of the groove at the bottom of the femur off to one side.  This shortens the tendons and ligaments that run across it, making them unable to straighten the leg completely until it pops back.  This is a genetic defect in a lot of small and toy breeds.  These dogs should NOT be bred, and surgery may need to be done if the condition is severe.

[michel]

It's lame.