Ph.D. (Zoology) / Please refer to full text to view abstract

Thesis (MMedVet. (Anaes))--University of Pretoria, 2000. / Also available in print format.

Thesis (Ph. D.) - University of California, Los Angeles, 1959. / "Literature cited": leaves 200-209.

The principle aim of this study was to isolate a chemical for the "safe anaesthesia" of abalone under commercial farming conditions. "Safe anaesthesia" implied that the anaesthetic had no immediate detrimental or long term sublethal effect on the abalone, that it was safe for the farmer, the consumer and the environment. Four chemicals, magnesium sulphate (MgS0₄), ethylenediamine tetra-acetic acid (EDTA), 2-phenoxyethanol and procaine hydrochloride were shown to effectively inhibit the in vitro contraction of isolated tarsal muscle of Haliotis midae. This identified them as potential anaesthetics for abalone. Since abalone, like any other aquaculture species, would be subject to frequent size-sorting during the grow-out period, size related dosage tables were developed for the four chemicals at a temperature of 18⁰C. Dosage tables were also developed for benzocaine and carbon dioxide (C0₂), Three size classes (5-15, 20-50 and 60-90 mm shell length (SL)) of abalone were considered. Only three of the six chemicals, viz. MgS0₄, 2-phenoxyethanol and CO₂, met the criteria of an effective abalone anaesthetic in that they effected rapid and mortality-free anaesthesia. The other three chemicals caused mortalities and were considered to be unsuitable for commercial scale anaesthesia. Temperature related dosage tables were then developed for MgS0₄ and CO₂, MgS0₄ concentrations and CO₂ flow rates for effective anaesthesia in abalone were found to be inversely related to temperature. The three size classes of H. midae were intermittently exposed to MgS0₄ and 2-phenoxyethanol anaesthesia for an eight month period to determine the effect of the anaesthetics on growth rate. Because of an increased resistance to the efficacy of 2-phenoxyethanol and high monthly mortalities it was concluded that this chemical was unsafe and unsuitable for commercial use. MgS0₄, on the other hand, had no effect on growth of abalone and no significant effect on the rate of mortality. MgS0₄ also had no measurable effect on H. midae muscle ultrastructure and, by implication had no effect on flesh texture. The use of MgS0₄ as an anaesthetic would, therefore, not affect marketability. Moreover, no magnesium residues were found in H. midae muscle tissue after short term or intermittent long term exposure to MgS0₄ anaesthesia. It was found that the three size classes of H. midae used in this study could be safely exposed to the recommended MgS0₄ concentrations for up to 40 minutes without any mortalities. This is more than adequate for routine farming procedures. Medium size abalone (20-50 mm SL) were also safely exposed to 14 g.100 ml⁻¹ MgS0₄ for up to 6 hours without any mortalities. The results have shown that MgS0₄ was undoubtedly the best chemical that was evaluated for anaesthesia of H. midae in this study. It fulfils the requirements set forth by the U.S.A. Food and Drug Administration (FDA) in that it is safe for the abalone, the farmer, the consumer and the environment.

There are approximately forty two million donkeys in the world. All developing countries have an expanding population of donkeys, which are used for the provision of various services. The most commonly performed procedures in donkeys are castrations, tumour removals, foot care and dental treatments. All of these procedures can be performed in standing donkeys provided sufficient analgesia and sedation are provided. The donkey should be recognised and treated in its own light. Very few analgesics relieve pain without producing side effects. The ideal analgesic would provide good analgesia and sedation without any side effects. Combined with sedation, analgesia aids in the handling of animals and reduces the danger to attendants. Neuroleptanalgesia provides a more potent sedative and analgesic allowing more procedures to be performed. A marked synergistic effect between opioids and alpha2 adrenergic agonists is reported. Detomidine-butorphanol is used extensively for equine sedation and analgesia in the United States of America and Europe. Currently there is limited information available on effective sedative and analgesic drugs or drug combinations in donkeys. Detomidine and xylazine, which belong to the alpha2 adrenergic agonist group, have been described for use in donkeys. No information exists on the use of opioid drugs or opioid-sedative combinations in donkeys. Detomidine produces sedation and analgesia of a greater magnitude and a longer duration than xylazine. Detomidine has been used to sedate horses for diagnostic, therapeutic or minor surgical procedures and as part of a premedication or an intravenous anaesthetic protocol. Detomidine is a good analgesic. The duration of sedation and analgesia is dose dependent. The sedation produced by detomidine alone is not always satisfactory and some horses will respond to noxious stimuli with well-directed kicks. For this reason, detomidine and butorphanol are very often combined. Butorphanol is a synthetic mixed agonist-antagonist opioid. The detomidine is given five minutes before the administration of butorphanol or the butorphanol can follow the detomidine. Sedation is easily extended by additional doses of detomidine and/or butorphanol. This combination produces profound sedation in which horses are apparently unaffected by sounds, tactile stimuli and surrounding activity. It has been suggested that donkeys require a higher dose of detomidine for sedation than horses. The recommended dose for donkeys is 20-40 µg/kg. The degree and length of analgesia and sedation is dose dependent. A dose of 5-10 µg /kg was found effective for sedation and a dose of 20 µg /kg was effective for sedation and analgesia. No recommended doses for butorphanol in donkeys exist. Twelve healthy male donkeys were randomly divided into two groups. One group received 10 µg/kg of detomidine while the other group received 10 µg /kg of detomidine and 25 µg /kg of butorphanol. Sedation was evaluated by a scoring system and characterised by lowering of the head, relaxation of the upper eyelids, drooping of the lower lip and dropping of the ears. Analgesia was evaluated by means of a pinprick method. The average dose for detomidine was 11.24 µg/kg and that of butorphanol was 28.0 µg/kg. The onset time to sedation was 4 minutes 21 seconds with detomidine alone and 3 minutes 28 seconds with the combination. The average length of sedation for the detomidine group was 20 minutes, and for the detomidine-butorphanol group was 1 hour and 7 minutes. The analgesia lasted twice as long in combination group compared to the detomidine group. Detomidine did not eliminate coronary band pain. Heart rates dropped significantly in the first minute after the injection in both groups, and this was statistically significant. There was however no statistical difference between the two groups. An atrioventricular and a sinoatrial block were recorded during this trial. The respiratory rates tended to decrease in the first few minutes after which the rate stabilised. Four donkeys receiving butorphanol had Cheyne-Stokes respiratory patterns. It was evident that the combination of detomidine and butorphanol produced a greater sedative and analgesic effect than detomidine alone. The superior sedation is the result of synergistic effects between detomidine and butorphanol. This trial has shown that detomidine in combination with butorphanol in donkeys produces sedation that is superior to detomidine on its own and last at least twice as long. Analgesia was dramatically improved with the combination as compared to detomidine alone. / Dissertation (MMed Vet (Anaesthesiology))--University of Pretoria, 2000. / Companion Animal Clinical Studies / unrestricted

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains iii, 33 p. : ill. Includes abstract. Includes bibliographical references (p. 17-21).

Thesis (M.Phil) - University of Queensland, 2004. / Includes bibliography.