NAVLE
Nervous
Bovine Peripheral Nerve Paralysis Study Guide
Peripheral nerve paralysis represents a significant category of neurological disease in cattle, most commonly occurring as a complication of dystocia (calving paralysis) or prolonged recumbency.
Overview and Clinical Importance
Peripheral nerve paralysis represents a significant category of neurological disease in cattle, most commonly occurring as a complication of dystocia (calving paralysis) or prolonged recumbency. Research indicates that among 104 cases of calving paralysis in dairy cows, sciatic syndrome was present in 96.2% of cases, obturator syndrome in 29%, and femoral syndrome in 15.4%. Multiple nerve involvement is common.
Neuroanatomy of the Bovine Lumbosacral Plexus
The lumbosacral plexus provides innervation to the pelvic limbs and arises from ventral rami of lumbar and sacral spinal nerves. Several nerves run along the inner walls of the pelvic canal, making them vulnerable to compression during parturition.
Peripheral Nerve Origins and Functions
High-YieldThe sciatic nerve is the LARGEST peripheral nerve in the body. It divides into the tibial (caudal branch) and peroneal/fibular (cranial branch) nerves. The peroneal nerve passes superficially over the lateral femoral condyle, making it vulnerable to pressure injury during recumbency.
Pathophysiology of Nerve Injury
Classification of Nerve Injuries
Mechanisms of Injury
- Compression/Ischemia: Pressure from oversized fetus during dystocia or prolonged recumbency. Sustained pressure greater than 20 minutes leads to temporary or permanent dysfunction.
- Stretching/Traction: Hyperextension or excessive abduction during calving or falls, particularly during hip-lock situations.
- Direct Trauma: Pelvic fractures, injection injuries (particularly gluteal region), or surgical complications.
- Secondary Damage: Compartment syndrome from muscle swelling causing progressive ischemic damage.
NAVLE TipCalving paralysis is now understood to primarily involve the L6 branch of the sciatic nerve rather than isolated obturator nerve damage. Both nerves can be affected, but sciatic involvement is more common (96.2% of cases).
Sciatic Nerve Paralysis
Etiology
- Dystocia with feto-pelvic disproportion (most common)
- Intramuscular injection injury in gluteal region
- Pelvic fractures or sacroiliac luxation
- Prolonged recumbency (compartment syndrome)
- Estrous activity injuries (mounting/falls)
Clinical Signs
- Fetlock knuckling (metatarsophalangeal joint) - bilateral in severe, unilateral in mild cases
- Inability to flex the stifle
- Inability to flex or extend hock and digits
- Hock excessively flexed when standing (if femoral nerve intact)
- Weak to absent withdrawal reflex
- Prominent patellar reflex (reduced antagonism from hamstrings)
- Analgesia distal to stifle (except craniomedial - saphenous territory)
Obturator Nerve Paralysis
Etiology
- Dystocia - hip-lock during anterior presentation
- Compression by oversized calf along medial aspect of ilium
- Slipping on wet/icy surfaces ('doing the splits')
- Poor handling in collecting yards
Clinical Signs
- Inability to adduct hindlimbs - classic presentation
- Base-wide stance with hindlimbs abducted
- Tendency to splay ('do the splits') especially on slippery surfaces
- Can bear weight when limbs positioned correctly
- No sensory deficits (obturator is purely motor)
- High risk of hip dislocation from uncontrolled abduction
High-YieldObturator paralysis rarely occurs in isolation - research shows it was diagnosed in 29% of calving paralysis cases but never as the sole cause of recumbency. Always evaluate for concurrent sciatic nerve involvement.
Peroneal (Fibular) Nerve Paralysis
Etiology
- Prolonged recumbency on hard surfaces (most common)
- Pressure ischemia over lateral stifle region (lateral femoral condyle)
- Periparturient hypocalcemia leading to recumbency
- Lateral condyle or tibial fractures
Clinical Signs
- Hyperflexion of fetlock (knuckling) - characteristic finding
- Walking on dorsum of fetlock in severe cases
- Hock appears overextended
- Can bear weight when foot properly positioned
- Reduced sensation on dorsal metatarsal area
- Often bilateral when related to prolonged labor
Tibial Nerve Paralysis
Clinical Signs
- Overflexion of hock ('dropped hock syndrome')
- Partial flexion of fetlock (slight knuckling)
- Gastrocnemius appears longer than normal
- May mimic gastrocnemius rupture (but rupture shows more severe hock drop)
- Can walk and bear weight, but gait is awkward
- Reduced sensation on plantar surface of foot
NAVLE TipKey differential: gastrocnemius rupture vs tibial paralysis. With tibial paralysis, hock drop is MODERATE and animal can still bear weight. With gastrocnemius rupture, hock drop is SEVERE, calcaneus markedly elevated, and animal CANNOT bear weight.
Femoral Nerve Paralysis
Clinical Signs
- Inability to extend the stifle - stifle collapses under weight
- Unable to bear weight on affected limb
- Weak to absent patellar reflex
- Rapid atrophy of quadriceps femoris within 7-10 days
- Calves with bilateral involvement adopt 'dog-sitting' posture
- Unilateral cases: pelvis tilted toward affected side
High-YieldFemoral nerve paralysis is most commonly seen in NEONATAL CALVES after difficult anterior presentation with hip-lock. Differentials include hip fracture and hip luxation.
Radial Nerve Paralysis
Etiology
- Prolonged lateral recumbency (pressure over lateral humerus)
- Casting with ropes - forelimb restrained, animal struggles
- Tilt table positioning during surgery
- Humeral fractures
- Forelimb trapped in fence or feeder
Clinical Signs
Distal Radial Nerve Paralysis (more common):
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