Diagnosing and treating downer cattle (Proceedings)
A downer cow is "a cow unable to stand voluntarily". Many are periparturient and due to traumatic peripheral nerve injuries.
Sciatic nerve paralysis is seen primarily immediately after calving. Feto-pelvic disproportion produces pressure ischemia on sciatic nerve, rarely secondary to injection abscess. The clinical signs include persistent knuckling of fetlock and slight "dropping" of the hock. Weight bearing variably affected - stifle joint extension maintained by femoral nerve. A prominent patella reflex (less antagonism of femoral nerve/quadriceps). May have decreased tail tone, anal sphincter tone, atonic bladder, may have analgesia of hindlimb distal to stifle (except craniomedial aspect of tibia).
Obturator nerve paralysis is seen primarily immediately after calving. Feto-pelvic disproportion produces pressure ischemia on obturator nerve (and more commonly on the L6 branch of the sciatic nerve!!). Clinical Signs are inability to adduct the hind limbs, tendency for abduction when standing, particularly on concrete or ice. May lead to dislocated hip, can support weight when hind legs are placed in normal position. Treatment should include hobbling the back legs to prevent splits (24" to 30" apart)Peroneal nerve paralysis is seen primarily in cattle immediately after parturition or prolonged recumbency. Pressure ischemia over lateral stifle region (lateral femoral condyle) is the cause. Clinical Signs include hyperflexion of fetlock joint (may walk on dorsum of fetlock), inability to extend digit, overextension of the hock. There may be possible skin analgesia dorsal metatarsal area, fetlock, and digit. Treatment includes bandage, splint, or cast fetlock to prevent abrasion
Radial nerve paralysis is seen primarily in adult cattle after prolonged lateral recumbency. Due to pressure ischemia over the lateral aspect of the humerus. Clinical signs include inability to extend (bring forward) the elbow, carpus, and digits. The leg is dragged, which abrades the fetlock. Skin analgesia is present on the lateral part of leg. Treatment includes bandage, splint, or cast leg (including carpal joint) to prevent fetlock abrasion.
General treatment principles for nerve injuries include confine to dry, softly bedded box stall (sand stall is best), and reduce perineural swelling by administering dexamethasone (0.05 mg/kg, IM, every 1-2 days; preferred) or flunixin meglumine (1 mg/kg, IM, q 12 h).
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