Mechanical nociceptive thresholds

In our investigation, the used mechanical pressure and needle pricks nociceptive threshold stimulators have different criterias to apply and subsequently could affect the recorded responses. Mechanical nociceptive threshold devices also can be applied to detect the efficacy of intravenous regional as well as nerve block anaesthesia and like electrical stimulators can be different regarding their type and their applications in different species. However, there are some factors which may affect the mechanical nociceptive threshold responses consist of timing of the clinical examination, the weight of animal, type as well as dosage of applied anaesthetic (JANCZAK et al., 2012; STEAGALL et al., 2007;

AMBROS and DUKE, 2013). The only criteria which should always be considered regarding mechanical nociceptive thresholds’ application is that to apply the mechanical nociceptive threshold device, the stimulus induction rate of stimulus must be the same from trial to trial (CHAMBERS et al., 1990). Therefore, not only the mechanical nociceptive stimulus must be the same but also stimulators have important criterias such as reproducibility as well as type of mechanical threshold device which could affect the recorded responses.

5.1.2.1. Mechanical pressure nociceptive thresholds

The first mechanical stimulation was induced by mechanical pressure nociceptive device in our study. Pressure nociceptive threshold testing device could be applied in different species (DIXON et al., 2007). According to CHAMBERS et al. (1990), mechanical stimulation device should be easy to use and can give reproducible responses as a result of mechanical stimulations. Mechanical pressure nociceptive threshold device which has been used in our study has such those criterias as mentioned above. They are easily to apply in different favorite sites of leg which are accessible and also responses could be repeated several times, therefore, those mechanical nociceptive threshold stimulators could be applicable to measure the pain. Our subjective mechanical pressure nociceptive threshold device not only was simple and reliable to apply with producing reproducible responses but also did not have a limitation of objective mechanical threshold stimulators which has been

DISCUSSION AND CONCLUSION

148

used by CHAMBERS et al. (1990). One of that limitations could be that stimulus as well as its application’s rate must be same from trial to trial. On the other hand, the experience of the operator may have possibly effect on the results of nociceptive threshold examinations (CHESLER et al., 2002). However, we had an enough experienced person to perform that and could be sure concerning this point. In our first study as an exam to consider the efficacy of anaesthesia, following local anaesthesia application with either intravenous regional anaesthesia or 4-point nerve block anaesthesia, dairy cows had a full desensitizd distal hind limb at lateral and medial bulb of heel, lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint. Furthermore, the mechanical pressure nociceptive threshold results of second part of study for onset of anaesthesia revealed that there is no difference between the speed of onset of anaesthesia at lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint and also lateral and medial bulb of heel following anaesthesia with either nerve block or intravenous regional analgesia. However, regarding the mechanical pressure nociceptive threshold responses from the examined dairy cows in our study, full anaesthesia could be obtained fiftheen minutes following intravenous regional anaesthesia in all six examined sites includes of lateral and medial bulb of heel, lateral and medial dorsalis fetlock joint as well as lateral and medial flexor tendon while nerve block anaesthesia was started at those six different sites following anaesthesia already. Regarding to our second study, the onset of anaesthesia would be faster about five minutes at skin of heel after 4-point nerve block anaesthesia compared to intravenous regional anaesthesia as well as seven and half minutes following anaesthesia’s application at the skin of dorso-lateral coronary band. Furthermore, the duration of anaesthesia would be the same between two anaesthesia techniques as there was not seen any significant difference fiftheen and thirty five minutes following anaesthesia with either four points regional nerve block or intravenous regional anaesthesia. It seems, if we had a plan to increase numbers of nociceptive threshold stimulations after anaesthesia with increasing the duration of lateral recumbency on surgical tilt table, that could be possible to get to know which anaesthesia technique would be ended sooner. However, regarding the time which veterinarians would need to perform any distal hind limb intervention, realizing the duration of full desensitized distal hind limb more than thirty five minutes following anaesthesia which could be gained under both anaesthesia methods would be great. However, veterinarians may select their choice anaesthesia method regarding the required time which they need for full desensitized distal hind limb in order that, according to our achieved results related to mechanical pressure nociceptive thresholds as well as pin pricks, no significant difference was seen related to type of anaesthesia

DISCUSSION AND CONCLUSION

149 technique.

5.1.2.2. Mechanical pin prick thresholds

Mechanical pin pricks nociceptive threshold as another means can measure the pain after anaesthesia’s application. As the results of first study revealed, full desensitized distal hind leg could not be significantly different between 4-point nerve block anaesthesia method and intravenous regional anaesthesia technique at lateral and medial bulb of heel, lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint. In other words, according to mechanical pin pricks nociceptive threshold responses, intravenous regional anaesthesia and 4-point nerve block anaesthesia could induce same adequate analgesia at lateral and medial bulb of heel, lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint. Therefore, there is no difference to choose intravenous regional or nerve block anaesthesia to have a full desensitization at lateral and medial bulb of heel, lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint.

However, regarding our evaluated results related to onset of anaesthesia, intravenous regional anaesthesia could be started about five minutes after anaesthesia’s application later than nerve block anaesthesia at dorso-lateral coronary band skin as well as soft skin of heel. Therefore, according to electrical pain stimulation results, to have a rapid onset of anaesthesia at the dorso-lateral coronary band skin and soft skin of heel’s interventions, nerve block anaesthesia would be the choice anaesthesia technique while according to mechanical nociceptive threshold responses using pin pricks as well as force device, there is no difference to choose one of those anaesthesia techniques includes of 4-point nerve block anaesthesia or intravenous regional analgesia to have full desensitized sites of lateral and medial bulb of heel, lateral and medial dorsalis fetlock joint as well as lateral and medial flexor tendon. However, according to results of our first study, application of intravenous regional analgesia or administration of 4-point nerve block anaesthesia has no remarkable difference to have a full or complete desensitized area at lateral and medial bulb of heel, lateral and medial flexor tendon as well as lateral and medial dorsalis fetlock joint. Nonetheless, the onset of anaesthesia would be still superior following 4-point nerve block anaesthesia compared to intravenous regional analgesia at both sites of dorso-lateral coronary band as well as soft skin of heel. Those achieved results demonstrated that before choosing the local anaesthesia technique, first of all, it’s better to identify the desired desensitized area which needs to have an intervention and depend on that site, anaesthesia method should be selected to perform. By this way, the veterinarians would have a full anaesthesia in minimum period of time which they need for

DISCUSSION AND CONCLUSION

150 distal hind limb’s surgical interventions.