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    An evaluation of the effectiveness of castellated laryngofissure and bilateral arytenoid lateralisation for the relief of laryngeal paralysis in dogs : a thesis presented for the degree of Master of Veterinary Science at Massey University
    (Massey University, 1989) Burbidge, Hilary
    In recent years, laryngeal paralysis in dogs, has become a frequently recognised disorder. Various surgical procedures have been advocated to relieve the consequential laryngeal obstruction, but few critical examinations of the effectiveness of these procedures have been attempted. The aim of this study was to determine and compare the efficacy of two of the more commonly used surgical methods (i) castellated laryngofissure with vocal fold resection and (ii) bilateral arytenoid lateralisation in providing an adequate laryngeal airway in dogs after surgically Induced laryngeal paralysis. The laryngeal function of ten adult healthy experimental dogs was assessed by clinical examination, laryngoscopy, blood gas and tidal breathing flow-volume loop analyses prior to and after bilateral recurrent laryngeal nerve resection. Five dogs then underwent a castellated laryngofissure with vocal fold resection and the remaining five, bilateral arytenoid lateralisation. Six weeks later, the laryngeal function of the ten dogs was reassessed using the same investigative techniques. Radiographs of the chest were taken at the start and completion of the experiment on the live dogs to help detect the presence of any co-existent lower respiratory tract disease. An autopsy was performed on each dog. six weeks after surgery, and details of visible changes in the laryngeal structure recorded. After neurectomy, all of the dogs had inspiratory stridor, a hoarse bark and reduced exercise tolerance. Medial displacement of the arytenoid cartilages and vocal cords caused narrowing of the rima glottidis. No abduction of these structures occurred during inspiration. There was a significant fall in arterial oxygen tension and inspiratory airflow recorded on blood gas analyses and tidal breathing flow-volume loop studies, respectively. The degree of relief from the laryngeal obstruction in the neurectomised dogs after castellated laryngofissure with vocal fold resection was variable. Some of the animals still had signs of respiratory embarrassment. The size of the rima glolhdis achieved was either slightly narrower or similar to that seen in the non-abducted. pre-neurectomised larynx of the experimental dogs. No significant improvement in blood gas or tidal breathing flow-volume loop analyses were recorded following the surgical technique. In contrast, bilateral arytenoid lateralisation consistently alleviated the clinical signs of bilateral recurrent laryngeal neurectomy. The rima glottidis width was increased to either the non-abducted, pre-neurectomised size or greater, depending on the position of the lateralisation suture. Furthermore, blood gas and tidal breathing flow-volume analyses recorded a significant increase in arterial oxygen tension and inspiratory airflow, respectively. Although bilaterial arytenoid lateralisation was more efficient than castellated laryngofissure with vocal fold resection in alleviating the laryngeal obstruction caused by bilateral recurrent laryngeal neurectomy, it did have some inadequacies. The fixed abduction of the arytenoid cartilages destroyed the expiratory braking mechanism of the larynx. Furthermore, execution of the surgical technique requires intimate knowledge of the anatomy of the larynx and the surrounding structures and, since the position of the lateralisation suture is imporlant,best results are likely to bo achieved by surgeons experienced with the procedure.
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    Assessment of tail docking and disbudding distress and its alleviation in calves : a thesis presented in fulfilment of the requirements for the degree of Master of Science by thesis only at Massey University
    (Massey University, 1994) Petrie, Natalie Jean
    In this age of increasing awareness of animal welfare, the demand for scientific methods to quantify the welfare of animals maintained under different conditions and exposed to different husbandry procedures has also increased. The aim of the present study was to examine the acute distress involved in the procedures of tail docking and disbudding of Friesian dairy calves. Different methods of tail docking (rubber ring and docking iron) and disbudding (scoop and cautery), with or without the use of a local anaesthetic, have been assessed using changes in plasma cortisol concentration and some behavioural observation as indices of distress. The practical objectives were to provide advice on choice of method and on the benefits or otherwise of using local anaesthetic to alleviate the pain associated with these procedures. The innervation at the docking site of the bovine tail and the efficiency of two methods of local anaesthetic administration (epidural and ring block) in desensitising the tail were assessed. Epidural local anaesthetic was found to totally desensitise the entire tail whereas a ring block adminstration of local anaesthetic around the docking site only effectively desensitised an area immediately adjacent to the site of ring block administration. Hence, to ensure total loss of sensation in the tail, an epidural administration of the local anaesthetic was used in the tail docking experiments. Tail docking, with or without a local anaesthetic, most three to four month old Friesian dairy calves was found to be no more distressing than control handling and blood sampling using both plasma Cortisol concentration and behavioural indices of distress. However, there was a degree of between-animal variation in response - a small proportion of calves which received some treatments that were not expected to cause distress showed signs of mild distress. The reasons for these responses are unknown. Disbudding six to eight week old Friesian dairy calves with a scoop caused a marked distress response which lasted for about five and a half hours, whereas the alternative method, the cauterising iron, was only slightly more distressing than control handling and blood sampling during the first one hour after disbudding. Although administration of a local anaesthetic before scoop disbudding produced a marked reduction in plasma cortisol concentration during the first two hours after treatment there was little or no reduction in overall distress, as judged by plasma cortisol responses. However, prior administration of a local anaesthetic to calves disbudded by cautery effected a slight reduction in the distress response, decreasing it to near control levels. The practical advice on method for these husbandry practices would be for tail docking, continued use of the rubber ring if tail docking is deemed necessary at all, and for disbudding, cautery alone or with local anaesthetic, if practically viable, would be recommended.
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    Assessment and alleviation of castration distress in lambs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University
    (Massey University, 1995) Dinniss, Andrew Selwyn
    There is increasing pressure on the farming community to assess and minimise the distress caused by husbandry procedures. This is due to an increase in awareness of animal welfare throughout New Zealand, and economic pressures from overseas. This study involved an investigations into the acute pain-induced distress of lambs caused by castration, the effectiveness of different anaesthetic methods to alleviate that distress, characterisation and validation of behavioural responses as indices of pain-induced distress, and the assessment of the use of the burdizzo to reduce the acute pain-induced distress caused by ring castration. The castration techniques examined were ring, burdizzo, and ring + burdizzo. Short scrotum creation was also assessed. The alleviation techniques were injections of local anaesthetic into the scrotum, spermatic cords, testes or the scrotum + spermatic cords, 15 minutes prior to castration. This study assessed the effectiveness of using a burdizzo before application of a rubber ring to reduce the distress, as indicated by cortisol and behaviour responses, caused by ring application. The concept of using a burdizzo to reduce the distress caused by ring castration was based on the hypothesis that 'disabling the afferent nerves from the testes would prevent nociception caused by ring application from being transmitted' (Kent et al. 1993,1995). It was found that the burdizzo used in the conventional manner (one application to each spermatic cord and the surrounding scrotal tissue with no overlap of 'cuts') together with ring application did not reduce the cortisol or behavioural responses to ring castration. Hence it is unlikely that pain will have been reduced. This study characterised the cortisol and behavioural response to burdizzo castration. The cortisol response was found to have a duration of 180 minutes with a magnitude similar to that exhibited by ring lambs. However, the values remained elevated for longer than ring in lambs. Although the cortisol response is likely to indicate noxious sensory input caused by burdizzo application, it cannot be proved, using the results of this study, that sensory-independent stimulation of the hypothalamic pituitary adrenal axis is not responsible for this cortisol response to burdizzo castration. Local anaesthetic administrated into the scrotum, spermatic cords plus scrotum, or testes was found to abolish the cortisol response and either reduce or abolish different behaviours after ring castration suggesting that pain-induced distress caused by application of a rubber ring was prevented. The cortisol response and some behaviours caused by burdizzo plus ring castration were also prevented by injecting local anaesthetic into the scrotum prior to treatment indicating that pain-induced distress was also prevented. Local anaesthetic injected into the spermatic cords reduced numerically (although not significantly), but did not abolish the cortisol response to ring or burdizzo plus ring castration. This suggested that the scrotum, which was presumed to be unanaesthetised, was a significant source of nociception after these two treatments. Local anaesthetic injected into the scrotum or spermatic cords did not reduce the cortisol or behavioural responses to burdizzo castration. This can lead to two conclusions; either local anaesthetic did not anaesthetise all the tissue effected by the burdizzo, or something other than sensory input stimulated the hypothalamic-pituitary-adrenal axis after burdizzo castration. Intuitively, the former seems most likely. Some behaviour parameters were found to be useful when comparing the pain-induced distress caused by similar treatments that elicited similar behaviours, but not when comparing between treatments that caused different types of tissue damage and elicited different behavioural responses. Burdizzo castration did not cause any obvious abnormal behaviours, suggesting that either no significant sensory input was caused by burdizzo application or that our behaviour observation methodology was not sensitive enough to pick up nuances of behaviour. Hence it was not possible to use behaviour to compare intensities of pain-induced distress caused by ring or burdizzo castration. Practically the use of the burdizzo in the conventional manner to reduce the pain-induced distress caused by ring application cannot be advised. Further work needs to be done to assess practical aspects of the modified use of the burdizzo (across the whole width of the scrotum suggested by Kent et al. 1993,1995) before it can be recommended as an alternative method of castration. The use of local anaesthetic in the field needs to be investigated further before it can be recommended. It seems that simple methods of local analgesia may be possible, however the danger of possible complications such as sepsis must be evaluated.