The dog's peripheral nervous system consists of several nerves branching out towards different parts of the body including the dog's extremities. When the nerves supplying the legs are damaged, dogs present gait changes, weakness, loss of sensation, foot dragging and even paralysis. The medical term for damaged nerves is neuropathy and in dogs this is often caused by trauma from automobile accidents. If your dog is showing signs of a leg nerve injury, see your vet promptly before complications set in.
A Lesson in Anatomy
The dog's central nervous system is composed of the brain and spinal cord. From the spinal cord, several peripheral nerves branch out for the purpose of relaying important information from the brain to the body. Several of these peripheral nerves are found in the dog's front and back legs. The nerves present in the dog's front legs consist of the radial nerve, median nerve and ulnar nerve; whereas, the nerves in the dog's back legs consist of the sciatic nerve, femoral nerve, fibular nerve and tibial nerve.
Nerve Injury Classifications
Nerves are fragile and can be damaged by being compressed, stretched and torn. Trauma and diseases such as cancer may damage nerves in different ways. _Neuropraxia_ is the less severe form, mostly causing a temporary dysfunction that may last several weeks, but the dog recovers completely. In axonotmesis, the nerve's axons, also known as nerve fibers, are ruptured but the nerve sheath is intact and still capable of enabling electric impulses to be conducted. _Neurotmesis_ is the most severe form with complete nerve rupture causing total loss of nerve function.
Front Leg Nerve Injuries
Traumatic injury of the dog's brachial plexus, a network of nerves located in the neck and shoulder area and extending towards the front legs, may cause detachment of nervous tissue from the spinal cord, a condition known as brachial plexus avulsion. Affected dogs may be unable to bear weight, dragging one foreleg, and presenting loss of sensation below the elbow. Further down, is the radial nerve, extending from the brachial plexus and reaching the forelimbs. This nerve is subject to injuries that may lead to radial nerve paralysis. While median nerve injuries won't alter the dog's gait, the dog's ability to perceive sensations may be affected; whereas, ulnar nerve injuries cause muscle atrophy.
Back Leg Nerve Injuries
Unlike the brachial plexus, injuries to the dog's lumbosacral plexus, a network of nerves extending towards the hind leg, are uncommon. Instead, the sciatic nerve, originating from the lumbosacral plexus and reaching the hind legs, may be subject to trauma as a result of a pelvic fracture, surgery or an intramuscular injection into the hip area. In femoral nerve injuries, the dog cannot extend the stifle to bear weight and may present muscle atrophy and loss of sensation. With fibular nerve damage, the hock overly extends and the toes appear knuckled; whereas, with tibial nerve damage, the hock overly flexes and the toes extend.
Diagnosis of Nerve Injuries
Dogs affected by leg nerve injuries will be evaluated by the vet. The physical examination consists of several neurological tests
Importance of Treatment
When a dog's leg suffers a nerve injury, muscle mass is lost quickly. Physical therapy may minimize muscle wasting while the nerve regenerates. For foot-dragging, a light bandage can help prevent injury. A brief course of anti-inflammatory drugs may be prescribed. While a therapy encouraging growth regeneration has yet to be invented, laser therapy, low level light therapy and photobiomodulation appear promising. Prognosis for leg nerve injury varies based on the extent of nerve damage and location, but generally, the closer the nerve injury to the muscle, the better the prognosis.