Brachial Plexus Avulsion

Brachial plexus avulsion is a peripheral nerve injury commonly seen in calves following dystocia or traumatic traction during assisted delivery. This condition results in flaccid paralysis of the thoracic limb, often with a dropped shoulder, absent panniculus reflex, and inability to bear weight.

Brachial Plexus Avulsion (BPA) in Cattle

Brachial plexus avulsion (BPA) is an uncommon but clinically significant condition in calves, typically resulting from excessive traction or abnormal limb abduction during parturition, particularly in dystocia cases. This injury involves damage or avulsion of the nerves comprising the brachial plexus, leading to profound neuromuscular dysfunction of the affected thoracic limb.

Clinical Presentation

Affected calves present with:

Inability to Extend Elbow, Carpus, and Fetlock: Inability to bear weight on the limb.
Dropped Elbow: The hallmark clinical sign, making the affected limb visibly lower than the contralateral limb.
Hoof Scuffing and Knuckling: The hoof scuffs during forward motion, and the foot often rests knuckled over.
Prominent Shoulder Blade Spine: Due to muscle atrophy.
Additional Signs: In some cases, ipsilateral Horner’s syndrome (ptosis, miosis, enophthalmos, protrusion of the third eyelid) and loss of the cutaneous trunci reflex.

Diagnosis

Diagnosis relies on a thorough clinical and neurological examination, including:

Observation of Posture and Gait: Assessing limb position and movement abnormalities.
Spinal Reflex Testing: Identifying deficits to localize the lesion to the brachial plexus.
Sensory Assessment: Detecting sensory deficits distal to the elbow.
Electromyography (Optional): To confirm muscle denervation and severity of nerve damage.

Differentials include:

Radial Nerve Paralysis: Often a result of traction injuries.
Spinal Cord Trauma: Considered if broader neurological signs are present.
Congenital Sarcocystosis: If multiple congenital abnormalities are noted.
Fractures: Typically ruled out due to lack of pain on palpation.

Treatment and Prognosis

Management of BPA is primarily supportive, focusing on:

Anti-inflammatory Medications: Corticosteroids or NSAIDs to reduce inflammation.
Splinting: Splinting the distal limb to prevent flexor tendon contraction.
Physical Rehabilitation: Physiotherapy to maintain joint mobility and minimize muscle atrophy.

Prognosis:

Mild Injuries: May recover with time, especially in cases of nerve contusion.
Severe Avulsion: Often leads to permanent deficits, and in cases where weight-bearing or sensation recovery is poor, amputation may be necessary.

Conclusion:

Prompt recognition and supportive management of BPA are critical, especially in calves with a history of difficult calvings. Early intervention and proper neurological evaluation are essential to optimize outcomes in affected animals.

References for Further Reading: