Also see Bovine Secondary Recumbency and see Limb Paralysis.
This rare condition results from paralysis of the supraspinatus and infraspinatus muscles caused by damage to the sixth and seventh cervical nerves. Acute trauma to the prescapular area (eg, struggling into a head gate) produces a nonspecific ataxia immediately after the injury. Several days after the injury, the muscles may show signs of wasting, indicating the possibility of permanent damage.
Chronic injury to the nerves causes marked wasting of the muscles within weeks. A specific gait aberration develops. The stride is shorter than normal; when weight is borne on the limb, it tends to swivel. In some cases, the cause may be nerve compression in or around the vertebrae (eg, an abscess or fracture), which may be identified on radiographs.
If the trauma is complicated, primary treatment must be directed toward resolving the immediate problem. However, if the clinical presentation suggests that the injury is localized to the nerve, immediate treatment with steroids or other anti-inflammatory agents is appropriate.
Distal radial paralysis results in an inability to extend the carpus and digit. Proximal radial paralysis prevents the animal from extending the elbow, carpus, and fetlock to bear weight.
The proximal radial nerve may be injured by stretching close to the brachial plexus, in which case the triceps muscles as well as the extensors of the carpus and digits may be compromised. The damage is frequently associated with casting an animal with ropes or with any situation in which the forelimb is accidentally restrained and the animal struggles violently to free itself. Either distal or proximal radial paralysis can result from prolonged recumbency in very heavy animals.
The distal radial nerve is vulnerable to injury in the musculospiral groove of the humerus, either from fractures or deep soft-tissue trauma. A lesion of the nerve proximal to the sulcus for the brachial muscle causes proximal radial paralysis.
Clinical Findings and Diagnosis
In proximal radial paralysis, the elbow drops, the carpus and fetlock are in partial flexion, and the limb is usually dragged. In distal radial paralysis, because the triceps muscles remain functional, dropping of the elbow is minimal. However, paresis affecting carpal and fetlock position is present.
Rapid improvement can be expected in most cases. Animals should be confined in a generously bedded stall. Anti-inflammatory drugs may be helpful, particularly in the early hours after the initial trauma. If skin sensation in the forelimb has been completely lost, the prognosis is guarded. When the condition persists for ≥2 wk, damage is likely permanent and the prognosis is grave.
Damage to the ischiatic and obturator nerves after intrapelvic parturient trauma may cause recumbency after calving. It may be a component of the downer cow syndrome (see Bovine Secondary Recumbency). The tibial and peroneal nerves are branches of the ischiatic nerve that can be damaged at extrapelvic sites.
Passage of a calf through the pelvis exerts pressure on the obturator nerve. The close association of the obturator nerve with the origin of the ischiatic nerve can complicate the interpretation of clinical signs.
Because the adductors are innervated by the obturator nerve, an animal adopts a base-wide stance or, in recumbency, a sitting position with both hindlimbs extended forward. There is considerable risk that the adductor muscles will be damaged and that permanent recumbency will result. In addition to the base-wide stance, knuckling of the fetlock may be present. This indicates injury of the ischiatic nerve. Both conditions may contribute to the downer cow syndrome (see Bovine Secondary Recumbency).
If obturator paralysis is recognized early enough, vigorous measures should be adopted to prevent complications involving the adductor muscles. The animal should be immediately transferred to a site where there is good footing (eg, a base of tenacious manure over which clean straw has been spread) to prevent slippage when the animal attempts to rise. The hindlimbs can be tied together with a soft nylon strap fixed below the hocks. The limbs are restrained from “spreading” >3 ft (1 m) apart.
In femoral paralysis, paralysis of the quadriceps muscles, which extend the stifle, and partial paralysis of the psoas major muscle, which flexes the hip, are seen.
Clinical Findings and Diagnosis
Femoral nerve paralysis is seen in large, newborn calves (eg, Charolais, Simmental) after the use of mechanical force during an assisted birth. Reduced quadriceps tonicity reduces tension on the patella with the result that a lateral patellar luxation may develop. Atrophy of the quadriceps soon becomes obvious and, although the patella can be replaced easily, the animal has extreme difficulty in walking. The condition may affect one or both limbs. The prognosis is related to the severity of the clinical signs.
Despite a fair or good prognosis, the animal may be unable to suckle unaided. The animal should be maintained in a well-bedded area, and colostrum should be given as soon as possible after birth. A radiographic study should be done to exclude fractures. The administration of anti-inflammatory drugs may be useful.
Peroneal paralysis results in paralysis of the muscles that flex the hock and extend the digits.
The peroneal nerve is the cranial division of the ischiatic nerve. It passes superficially over the lateral femoral condyle and the head of the fibula, which makes it vulnerable to external trauma or pressure from recumbency. An affected animal stands with the digit knuckled over onto the dorsal surface of the pastern and fetlock. The hock may appear to be overextended. In mild cases, the fetlock tends to knuckle over intermittently during ambulation; however, this may also occur if the animal is experiencing pain in the heels.
In severe cases, the dorsal surface of the hoof may be dragged along the ground, and sensation to the dorsum of the fetlock is often decreased. Testing of reflexes may demonstrate that hock flexion is absent, but stifle and hip flexion are normal. This would not be the case if the ischiatic nerve was involved.
Most cases resolve naturally. However, if the condition is associated with long periods of recumbency, care must be taken to avoid exacerbation of the initial injury.
In tibial paralysis, there is paralysis of the extensors of the hock and flexors of the digits.
The tibial nerve is the caudal branch of the ischiatic nerve, which, in its proximal course, is well protected by the gluteal muscles. Distally, it progresses beneath the tendon of the gastrocnemius muscle and can be damaged when the tendon is traumatized.
The hock joint is overflexed (dropped hock syndrome) and the fetlock is partially flexed. The gastrocnemius appears to be longer than normal and gives the impression that it or its tendon could be ruptured. The fetlock tends to be buckled, but the animal can walk and bear weight, although its attempts to do so are awkward. Compared with that seen in peroneal nerve injury, the gait disturbance is mild, but the postural disturbance could be permanent.
The use of anti-inflammatory drugs may be of value in the early stages. However, the primary efforts should be directed toward ensuring that the animal does not injure itself further, by maintaining it on surfaces with good footing.
(Progressive hindlimb paralysis)
Episodic, involuntary muscle contractions or spasms involving the hindlimbs are associated with postural and locomotor disturbances as well as spasticity. The condition may progress to posterior paresis or hindlimb paralysis. It is seen most frequently in Holstein and Guernsey cattle 3–7 yr old. Spastic syndrome is regarded as a genetic disease, possibly due to an autosomal dominant gene with incomplete penetrance. The pathology and pathophysiology remain obscure.
Clinical signs may vary in severity, duration, and frequency. Usually, some stimulus provokes the onset of clinical signs, such as the effort associated with rising or any factor that induces a significant emotional reaction. Pain, particularly in the feet or joints, may precipitate an attack. During an attack, the animal may be unable to move forward, stands trembling, and characteristically extends its hindlimbs backward. Between episodes, the animal can ambulate normally.
Spastic syndrome is progressive, and because of the possibility of genetic transmission, animals (particularly bulls used for artificial insemination) are best eliminated as soon as a positive diagnosis is made. Palliative treatment for animals in the peak of production may be helpful. Mephenesin (30–40 mg/kg, PO, for 2–3 days) may be given during an episode. Phenylbutazone may also have beneficial effects.
Spastic paresis is a progressive unilateral or bilateral hyperextension of the hindlimb(s). It is seen sporadically in most breeds of cattle. Post-legged cattle are most frequently affected. Attempts to move are believed to simultaneously trigger contractions of both extensors and flexors of the limb. Spastic paresis is currently considered to be inherited via a recessive gene(s) with incomplete penetrance.
The disease may be seen within the first 6 mo of life. As the animal ages, the gastrocnemius muscles gradually contract. The hock and stifle become increasingly extended. Over a period of months, the hindlimbs become so stiff that the animal walks with short pendulum-like steps. If only one limb is affected, the animal stands with the affected limb camped back and the sound limb held toward the midline to maintain balance. If both hindlimbs are affected, the animal may attempt to bear more weight on the forelimbs by holding them well back and simultaneously arching its back.
There is no successful medical treatment. Because spastic paresis is heritable, affected animals (especially breeding bulls) should be eliminated from the herd. Palliative surgical treatment may be attempted, although ethical issues should be considered when breeding stock is involved. The procedures, usually performed on calves, include complete tenotomy of the gastrocnemius tendon, which results in a dropped hock; complete tibial neurectomy, which results in sufficient relief to permit a steer to be finished for slaughter; and partial tenectomy of the 2 insertions of the gastrocnemius muscle and the calcanean tendon sheath, which overcomes the problem of the dropped hock.
Last full review/revision March 2012 by Paul R. Greenough, FRCVS