Difficulty walking in the back legs may be due to neurological problems (most likely in your Dachshund), orthopedic problems (for example hip or knee problems), or cardiovascular problems (blood clot to the back legs as one reader replied).

Based on your description of inability to use the back legs, poop or pee, I would be most suspicious of a spinal cord injury. Possible causes of spinal cord injury include a slipped disk (or 'pinched nerve' as some previous responders call it), meningitis, spinal cord tumors (cancer), strokes (what's called a fibrocartilagenous embolism or FCE for short), trauma (such as gunshot wounds or being hit by a car), or sometimes spinal cord infections. "Tick paralysis" usually affects all four legs and not just the back ones.

Dachshunds and other 'long-back' breeds such as Shih-tzu's, Pekingese, Chihuahuas, Beagles, etc are prone to slipped disks. They tend to affect dogs between 2-7 years of age, but older and younger dogs may be affected as well.

Treatment options depend on how affected your pet is and whether surgery is an option for the pet. The most important factor is whether or not your dog can feel his or her back legs. A veterinarian should be able to assess this for you. In general, dogs that are unable to walk due to a slipped disk are usually best treated with surgery. Specialized training and advanced testing such as an MRI or CAT scan are often needed. The chances of fixing a dog that is unable to walk, but CAN feel their back legs is about 95% with surgery and about 50-60% with rest and medications. Strict crate rest is important. If your dog can NOT feel the back legs (as determined by a vet), the chances are not quite as good. More information about conservative management can be found at www.dodgerslist.com

More information about slipped disks in dogs can be found at [link to sevneurology.com]