Hypothesis 3 - Iatrogenic Fracture with Concurrent Nerve Damage

When the calf jack was used to extract the calf, it is attached to the distal limbs and significant force is applied, frequently causing trauma to the limb.  This could cause a fracture of the left metacarpus as seen in this calf.  This is supported by the crepitus, instability, non-weight bearing and crooked left limb.  Additionally, the force of the calf jack could result in nerve damage to the affected limb.  Specifically, radial nerve damage with possible median and ulnar nerve paralysis.  The clinical presentation of this calf appears to support any of the above.  Partial radial paralysis is relatively common due to direct trauma to the nerve.  Distal radial paralysis causes the inability to extend the carpus and the digit.  The limb is dragged causing abrasions to the dorsum of the fetlock.  The inability to extend the distal portion of the limb would lead to non-weight bearing limbs.  With these injuries other nerves of the brachial plexus are often involved.  Median and ulnar paralysis would cause paralysis of flexors of the carpus and digits.  These nerves could be damaged if severe force was applied to the limb, causing severe trauma to the axillary region.  In this case we observed a calf with a non-weight bearing lameness since birth (time of trauma to leg), raised toes, knuckling of the fetlock and extensive skin abrasions.  The raised toes could be caused by median or ulnar nerve paralysis which would lead to flexor defecit.  The knuckling and sensory defecit to the skin could be caused by radial nerve damage.  The radial nerve provides sensory innervation to the skin on the lateral side of the forelimb, elbow and carpus as well as motor innervation to limb extensors.  These defecits would lead to the skin abrasions seen in this calf.