Peroneal nerve paralysis results in paralysis of the muscles that flex the hock and extend the digits.
Clinical Findings of Peroneal Nerve Injury in Cattle
The peroneal nerve is the cranial division of the sciatic 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 lateral recumbency on a hard surface such as concrete, particularly during parturition with concurrent periparturient hypocalcemia. An affected animal stands with the digit knuckled over onto the dorsal surface of the pastern and fetlock (metatarsophalangeal joint). The hock may appear to be overextended. In mild cases of peroneal nerve paralysis, the fetlock tends to knuckle over intermittently during ambulation.
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 joint flexion are normal. This would not be the case if the sciatic nerve were involved.
Treatment of Peroneal Nerve Injury in Cattle
Most cases of peroneal nerve paralysis involve neurapraxia that will resolve with conservative management. However, if the condition is associated with long periods of recumbency, care must be taken to avoid exacerbation of the initial injury.