Objective—To determine whether epidurally derived evoked potentials (EPs) can be used to reliably assess nociception and antinociception in ponies.
Procedures—EPs and electromyograms (EMGs) from the quadriceps femoris muscles were recorded simultaneously, following electrical stimulation applied to the distal portion of the hind limb. The effect of increasing stimulus intensity, conduction velocities of the stimulated nerves, effect of epidurally applied methadone, and effect of systemically administered propofol were evaluated.
Results—In the EP and EMG waveforms, 2 distinct complexes, the EP N25 and P50 and the EMG P27 and N62, respectively, were identified. On the basis of their latency and calculated conduction velocities, the EP P50 and EMG N62 were considered to be related to nociception (AD-mediated). All complexes increased significantly in amplitude with increasing stimulus intensity and decreased significantly following epidural administration of methadone or systemic administration of propofol.
Conclusions and Clinical Relevance—Although the experimental setup allowed successful discrimination between tactile- and nociceptive-associated responses, the identified EPs, considered to reflect activity in the spinal cord, could not be definitively differentiated from activity in the lumbosacral epaxial musculature. Further research is required to refine measurement techniques to allow for discrimination between these 2 signals. Similar to other species, neurophysiologic variables such as EPs could potentially become a useful additional tool in quantifying nociception in equidae.
Objective—To evaluate methods for on-farm measurements
of uterine contractility in postpartum dairy
cows by comparing data simultaneously recorded by
use of 2 intrauterine pressure (IUP) devices and quantified
electromyographic (EMG) signals.
Animals—5 cows during the first 48 hours after parturition.
Procedure—2 EMG electrodes were implanted on
the surface of the gravid uterine horn. Parturition was
induced by injection of a prostaglandin F2α analogue
at day 274 of gestation. An open-tip catheter and pressure
microtransducer were transcervically inserted
and affixed to a caruncle immediately after calving.
Changes in IUP were recorded concurrent with EMG
recordings during 2-hour periods at 2, 6, 12, 18, 24,
36, and 48 hours after parturition. Novel acquisition
and analysis software programs were used with a digital
data-filtering capability for evaluation of IUP and
Results—The method for intrauterine fixation of the 2
pressure measurement instruments was effective
and allowed easy, externally guided removal of the
devices 48 hours after parturition. There was a high
correlation between the data obtained by the 2 pressure
measuring systems. Good correlation was also
found between pressure data obtained by the open-tip
catheter system and EMG signals. Although the
quantified IUP and EMG signals were highly comparable,
synchronization was not always evident during
visual inspection of these signals.
Conclusions and Clinical Relevance—The open-tip
IUP catheter system with a special fixation method is
suitable for use in on-farm studies. It will enable
investigators to record natural and pharmacologically
influenced uterine contractility in early postpartum
dairy cows. (Am J Vet Res 2005;66:1605–1615)