Brachial Plexus Avulsion in Dogs

The brachial plexus is a collection of nerve tissue arising from the spinal cord, which gives rise to the individual nerves that supply the forelimbs. Avulsion of the brachial plexus refers to stretching and tearing of this nerve tissue. The nerves are usually torn from their root of attachment to the spinal cord. 

The most common cause of brachial plexus avulsion is vehicular trauma, but any type of trauma that results in significant traction on the forelimb, resulting in overstretching of the armpit/shoulder area, may result in brachial plexus avulsion. The avulsion results in severe weakness or paralysis of the affected forelimb. 

What to Watch For 

Dragging one foreleg, especially dragging of the toes on the ground

Inability to support weight on the affected limb

Loss of sensation in the leg below the elbow

Animals may also develop Horner's syndrome on the same side as the injury. This is an ocular problem causing a sunken eye, small pupil, raised third eyelid and droopy top eyelid. The nerves that control part of the eye arise from the same area of the spinal cord as the brachial plexus. Therefore trauma to the plexus can result in ocular abnormalities as well.

Diagnostic tests

History and physical exam are important for any illness or injury. Determining if a trauma has occurred, when it occurred and how the pet has been acting is important. Physical examination will help your veterinarian localize the lesion and determine that the cause of the foreleg problem is neurologic and not related to a bone or muscle problem.

A neurologic exam is performed to evaluate limb motion, sensation and reflexes. The results of this test will also help your veterinarian determine if nerve damage is the cause of the injury.

Electrical stimulation tests of the limb are infrequently done to evaluate nerve conduction and the degree of nerve damage. This test requires specialized equipment and referral to a specialist may be necessary.

Treatment

There is no specific treatment for brachial plexus avulsion. Supportive care and physical therapy on the limb can sometimes help.

If neurologic function has not returned within 4 to 6 weeks, recovery is very unlikely. If there is complete nerve disruption, healing will not occur. In these cases leg amputation is advised to prevent recurrent trauma secondary to dragging the foot. Additionally, some animals will self-mutilate due to abnormal limb sensation.

Home Care

There are no specific treatments to be given at home. Monitoring for signs of improvement, in conjunction with veterinary evaluation is important.