Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Author: search.filters.author.Mellor DJEnd date: 1979

Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Effects of halothane on the electroencephalogram of the chicken
    (John Wiley and Sons, Ltd, 15/05/2018) McIlhone AE; Beausoleil NJ; Kells NJ; Johnson CB; Mellor DJ
    Little is known about the effects of inhalant anaesthetics on the avian electroencephalogram (EEG). The effects of halothane on the avian EEG are of interest, as this agent has been widely used to study nociception and analgesia in mammals. The objective of this study was to characterize the effects of halothane anaesthesia on the EEG of the chicken. Twelve female Hyline Brown chickens aged 8-10 weeks were anaesthetized with halothane in oxygen. For each bird, anaesthesia was progressively increased from 1-1.5 to 2 times the Minimum Anesthetic Concentration (MAC), then progressively decreased again. At each concentration, a sample of EEG was recorded after a 10-min stabilization period. The mean Total Power (PTOT ), Median Frequency (F50) and 95% Spectral Edge Frequency (F95) were calculated at each halothane MAC, along with the Burst Suppression Ratio (BSR). Burst suppression was rare and BSR did not differ between halothane concentrations. Increasing halothane concentration from 1 to 2 MAC resulted in a decrease in F50 and increase in PTOT , while F95 increased when MAC was reduced from 1.5 to 1. The results indicate dose-dependent spectral EEG changes consistent with deepening anaesthesia in response to increasing halothane MAC. As burst suppression was rare, even at 1.5 or 2 times MAC, halothane may be a suitable anaesthetic agent for use in future studies exploring EEG activity in anaesthetized birds.
  • Thumbnail Image
    Item
    Updating Animal Welfare Thinking: Moving beyond the 'Five Freedoms' towards 'A Life Worth Living'
    (14/03/2016) Mellor DJ
    Gaining knowledge of animal welfare and applying it in ways that improve our care of animals can be understood as a journey. Different countries, regions of countries and people within those countries have reached different stages in this journey. However, even for those who have travelled far on this journey, it will never end because new or modified approaches to animal care will be needed as we continue to learn more about how animals perceive and respond to the circumstances in which they find themselves.
  • Thumbnail Image
    Item
    Updating Animal Welfare Thinking: Moving beyond the "Five Freedoms" towards "A Life Worth Living".
    (14/03/2016) Mellor DJ
    The Five Freedoms have had major impact on animal welfare thinking internationally. However, despite clear initial statements that the words 'freedom from' should indicate 'as free as possible from', the Freedoms have come to be represented as absolute or fundamental freedoms, even rights, by some animal advocate and other groups. Moreover, a marked increase in scientific understanding over the last two decades shows that the Freedoms do not capture the more nuanced knowledge of the biological processes that is germane to understanding animal welfare and which is now available to guide its management. For example, the named negative experiences of thirst, hunger, discomfort and pain, and others identified subsequently, including breathlessness, nausea, dizziness, debility, weakness and sickness, can never be eliminated, merely temporarily neutralised. Each one is a genetically embedded element that motivates animals to behave in particular ways to obtain specific life-sustaining resources, avoid or reduce physical harm or facilitate recovery from infection or injury. Their undoubted negativity creates a necessary sense of urgency to respond, without which animals would not survive. Also, the temporary neutralisation of these survival-critical affects does not in and of itself generate positive experience. This questions the commonly held assumption that good animal welfare will result when these internally generated negative affects are minimised. Animals may also experience other negative affects that include anxiety, fear, panic, frustration, anger, helplessness, loneliness, boredom and depression. These situation-related affects reflect animals' perceptions of their external circumstances. Although they are elicited by threatening, cramped, barren and/or isolated conditions, they can often be replaced by positive affects when animals are kept with congenial others in spacious, stimulus-rich and safe environments which provide opportunities for them to engage in behaviours they find rewarding. These behaviours may include environment-focused exploration and food acquisition activities as well as animal-to-animal interactive activities, all of which can generate various forms of comfort, pleasure, interest, confidence and a sense of control. Animal welfare management should aim to reduce the intensity of survival-critical negative affects to tolerable levels that nevertheless still elicit the required behaviours, and should also provide opportunities for animals to behave in ways they find rewarding, noting that poor management of survival-critical affects reduces animals' motivation to utilize such rewarding opportunities. This biologically more accurate understanding provides support for reviewing the adequacy of provisions in current codes of welfare or practice in order to ensure that animals are given greater opportunities to experience positive welfare states. The purpose is to help animals to have lives worth living, which is not possible when the predominant focus of such codes is on survival-critical measures. Finally, an updated characterisation of animal welfare that incorporates this more accurate understanding is presented.
  • Thumbnail Image
    Item
    A Life Worth Living with Dr David Mellor. Interview by Luna Allison, Canadian Federation for Animal Welfare.
    (18/08/2016) Mellor DJ
    Dr. David Mellor is a leading animal welfare thinker and the Foundation Director of the Animal Welfare Science and Bioethics Centre at Massey University’s Institute of Veterinary, Animal and Biomedical Sciences in New Zealand. Dr. Mellor has more than 50 years of teaching and research experience and has developed animal welfare standards, regulations and legislation internationally. He has been widely recognized for making major contributions to animal welfare around the world through consultation, teaching and more than 500 scientific publications. We sat down with Dr. Mellor during his time in Toronto this spring to discuss animal welfare in Canada and advancing our thinking for the betterment of animals.