Pressure-induced changes in fibular motor nerve conduction velocity and fibularis (peroneus) tertius muscle-evoked potentials in a goat model of the downer cow syndrome.

A study was conducted to determine the acceptable fibular motor nerve conduction velocity (NCV) in goats and to characterize pressure-induced changes in conduction velocity and muscle-evoked potentials (MEP). The acceptable motor NCV in the adult goat was determined to be 95.9 +/- 6.8 m/s. Limb compression in recumbent cows was modeled by application of external compression to the goat pelvic limb to increase IM pressure to a minimum of 50 mm of Hg. This pressure, when applied for a 6-hour period, caused a 30% to 100% reduction of fibular motor NCV and a 10% to 100% reduction of amplitude of MEP measured from fibularis (peroneus) tertius muscle. The reduction of motor NCV and MEP was associated with clinically evident limb dysfunction. The changes detected by the electrodiagnostic tests were proportional to the magnitude and duration of the locomotor deficits. The limb dysfunction was accompanied by muscular damage indicated by an increase of serum creatine kinase activity.