Rear leg dragging

My 12-year-old Cocker Spaniel has recently started dragging her right back leg. I can hear the occasional clicking from her nail on the pavement. Is this serious? What do you think might be causing it and what can be done?

Graham Finch advises…

What you describe makes me immediately think of a nerve problem. The nerves that supply the legs come from the spine and descend into the leg muscles. These are both motor nerves (which get the muscles to move) and sensory nerves (providing information as to where the leg is positioned, as well as pain, pressure, heat and so on). During walking, this works together to produce a coordinated gait. When things go awry, a dog loses his ability to co-ordinate properly and you notice dragging. You may also notice some muscle wastage over the leg, which occurs if the motor nerves are not working properly or the leg is not being used as much.

The most likely cause of this would be a degeneration of the discs between each vertebrae, or inflammation around the joints – arthritis if you like – which then presses on the nerves. There could also be a number of other causes, but these would be the most common, in my experience. X-rays and perhaps even an MRI would pinpoint particular issues, though it’s possible both of these may appear normal in the early stages of the disease or in particular conditions such as a fibrocartilaginous embolus (one of the rare ones). In my experience, most dogs benefit from some form of anti-inflammatory treatment, together with gentle physio or hydrotherapy.

The key thing to watch out for would be sudden deterioration, gradual worsening, or the other hindlimb becoming affected. For owners that are really keen to get to the bottom of things, I might also recommend referral to a neurologist specialist, as they have access to advanced imaging techniques (such as CT and MRI scans). I would definitely suggest a check-up at the vet’s at your earliest opportunity.