Paralysis of a leg often results from damage to the peripheral spinal nerves. Paralysis of a front leg is usually associated with injury to the nerve roots in the neck or shoulder, or injury to the musculocutaneous, radial, median, or ulnar nerve in the leg. Paralysis of a hind leg is usually associated with injury to the nerve roots in the lower back or tailbone, or the femoral, sciatic, peroneal, or tibial nerve in the leg.
The animal’s posture and gait, spinal reflexes, pain sensation, and the condition of the muscles in the affected limb are evaluated to identify the location of the injury. The closer a nerve injury is to the muscle, the better the outlook for recovery, so it is important to determine the exact location of the injury. The ability or inability of the animal to flex the joint and bear weight on the leg, and the presence or absence of pain sensation and reflexes at various places in the leg, depend on the site of the nerve damage. Within a few days, muscles wither and lose mass because of the lost nerve connection. Measuring the electrical activity of the muscles (a procedure called electromyography) 7 to 10 days after the injury can also help determine the location of the damage.
Nerves regenerate slowly (at the rate of about 1 inch per month), and full functional recovery depends on the condition of the nerve sheath and on the distance between the injury and the muscle where the nerve ends. Some nerve injuries can resolve after several weeks or months; however, when total nerve rupture occurs, surgical reattachment is required for regeneration.
If an abnormal eye condition known as Horner’s syndrome (pupil small, eyelid partially closed, and third eyelid elevated) is present on the same side of the body as a completely paralyzed front leg, then the nerve roots have been torn and the chances for recovery are minimal. If Horner’s syndrome is not present with front leg paralysis, the outlook for recovery may be better.
Applying heat, performing massage, and stretching tendons should be done as directed to keep muscles, tendons, and joints of a paralyzed leg healthy while the nerve is regenerating. A light, but not tight, bandage may prevent damage to the foot from dragging. If the leg drags on the ground, it can be held up with a sling to prevent damage to the paw.
No specific therapy is available to help nerve regeneration. Acupuncture or laser therapy may help recovery. If voluntary movement, pain sensation, and spinal reflexes improve over 1 to 2 months, the outlook for recovery is good. An Elizabethan collar may be needed to prevent the cat from chewing on its leg. If the nerve injury is suspected to be permanent and the animal is chewing the leg, amputation may be the best option. Three-legged cats generally have a good quality of life.
Tumors located at or near the nerve roots can also result in paralysis of one limb. Lymphosarcoma is the most common tumor to affect these locations in cats. Chemotherapy may improve the length and quality of life in affected cats.
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