title: Effect of romifidine on the nociceptive withdrawal reflex and temporal summation in conscious horses.
abstract: OBJECTIVE
  To investigate the action of a single IV administration of romifidine on the thresholds of the nociceptive withdrawal reflex (NWR) and temporal summation in conscious horses.
  
  
  METHODS
  10 adult horses.
  
  
  METHODS
  Single electrical stimulations were applied on the digital nerves to evoke NWR from the left forelimb and hind limb. Repeated electrical stimulations (10 stimuli, 5 Hz) were given to obtain temporal summation. Surface electromyographic reflex activity was recorded from the common digital extensor and cranial tibial muscles. After baseline assessment of NWR and temporal summation thresholds, romifidine (80 microg x kg(-1), IV) was administered. Successive determinations of NWR and temporal summation thresholds were performed 5, 25, and 55 minutes after administration.
  
  
  RESULTS
  Romifidine significantly increased the current intensities necessary to evoke NWR and temporal summation in forelimbs and hind limbs of horses. Values were significantly higher than baseline values 55 minutes after romifidine administration. After administration of romifidine, a facilitation of reflex components of tactile origin was observed when repeated stimulations were applied.
  
  
  CONCLUSIONS
  Results confirm antinociceptive activity of romifidine and may represent an objective demonstration of the well-known hypersensitivity to tactile stimuli observed in horses receiving alpha2-adrenoreceptor agonists in clinical practice. Romifidine can be included in analgesic and anesthetic protocols to provide additional analgesia in horses.
authors.affiliation: Anesthesiology Section, Department of Clinical Veterinary Sciences, Vetsuisse Faculty, University of Berne, Switzerland.
authors.forename: Claudia
authors.initials: C
authors.lastname: Spadavecchia
authors.forename: Lars
authors.initials: L
authors.lastname: Arendt-Nielsen
authors.forename: Ole K
authors.initials: OK
authors.lastname: Andersen
authors.forename: Luciano
authors.initials: L
authors.lastname: Spadavecchia
authors.forename: Urs
authors.initials: U
authors.lastname: Schatzmann
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004576:Electromyography / Q000662:veterinary; D005260:Female; D005552:Forelimb; D006614:Hindlimb; D006736:Horses / Q000502:physiology*; D007093:Imidazoles / Q000008:administration & dosage / Q000494:pharmacology*; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D010147:Pain Measurement / Q000187:drug effects* / Q000662:veterinary*; D012018:Reflex / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D007093:Imidazoles; C076257:romifidine