Practical anaesthesia and analgesia for surgical castration and dehorning of extensively managed ...

231 Pages·2017·3.44 MB·English

Practical anaesthesia and analgesia for surgical castration
and dehorning of extensively managed beef cattle

Dominique Therese McCarthy
BAnVetBioSci (Hons II Class 1)

A thesis submitted in fulfilment of the requirements for the degree of
Doctor of Philosophy

The University of Sydney
Sydney School of Veterinary Science
Faculty of Science

June 2017

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Declaration
This thesis is submitted to The University of Sydney in fulfillment of the requirements for the
Degree of Doctor of Philosophy.
The work presented in this thesis is original except as acknowledged in the text. I hereby declare
that I have not submitted this material, in either full or in part, for a degree at this or any other
university.
Signature: Date: 28.06.2017
Dominique Therese McCarthy
BAnVetBioSci (Hons II Class 1)
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Acknowledgements
I would firstly like to thank and acknowledge my supervisors, Dr Peter White and Dr Sabrina
Lomax, for your unwavering support and encouragement throughout this PhD. Thank you for your
guidance and assistance with every part of this project and the preparation of this thesis. The
invaluable knowledge and skills I have gained throughout this PhD are due to your tireless efforts
and genuine desire for me to succeed. I have loved the past few years working on this project with
you and I am so grateful that I was given the opportunity to do so. Most of all, thank you for your
friendship which has made this experience so enjoyable.
I would also like to thank Professor Emeritus Peter Windsor for your significant input to the
preparation of this thesis. Thank you for being so generous with your time and for so gladly
assisting me. Thank you also for facilitating, throughout my PhD, networking opportunities for
myself which were extremely rewarding.
Thank you to Associate Professor Peter Thomson and Dr Evelyn Hall for your assistance with
statistical analysis throughout my PhD. Your expertise in this area is highly valued and with your
guidance, I have gained important knowledge and skills.
I would like to acknowledge property managers Mr Steve Burgun, Mr Chris Croker and Mr Greg
Schofields and the organisation Australian Country Choice, as well as all their staff. Your
significant contribution to the collection of data was essential to the development of this PhD
thesis. Thank you all for being so accommodating, co-operative and generous with your time,
facilities and animals. I was so fortunate to work with such pleasant and easy-going people.
I would like to acknowledge Meat and Livestock Australia for the provision of research funds and
my scholarship. I would also like to acknowledge the matching funds provided by the Australian
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Government and Bayer Animal Health. The opportunities, knowledge and skills I have gained
throughout this PhD have been extremely valuable. Thank you to Bayer Animal Health and Troy
Laboratories for their support of these studies and their provision of pharmaceutical products.
To my family and friends, thank you for the sincere interest you have shown in my research and
for understanding the importance of this PhD to me. Special thanks to my aunt, Anne, for gladly
spending a significant amount of your time proofreading my thesis before submission.
Thank you especially to my immediate family for your love and support throughout this PhD. To
my parents, Michael and Maureen, your genuine pride and interest in my PhD has meant so much
to me. Thank you for always taking care of me and making it as easy as possible to complete this
journey. To my sisters, Alexandra and Odette, I am so grateful for your faith and pride in me and
for your genuine happiness when I achieve my goals. Your love has meant everything to me.
Finally, to my fiancé, Matt, thank you for your ongoing love and encouragement throughout my
PhD. I am so fortunate to have had you to look out for me and take care of me throughout this
PhD. I have looked to you for motivation throughout this journey. You are, and always will be,
my inspiration.

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With loving memory, I dedicate this thesis to my grandfathers, Maurice Colreavy and John
McCarthy.

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Abstract
Castration and dehorning are routine husbandry procedures commonly performed on cattle within
the beef industry. Although there is extensive literature demonstrating the pain and distress
resulting from these procedures, they have traditionally been performed without anaesthesia or
analgesia due to the practical constraints associated with administering injections on-farm.
Consumer demand for improved production animal welfare is continuously increasing. The beef
industry therefore needs to address issues of concern, such as painful husbandry procedures, to
ensure a sustainable future. Ceasing castration and dehorning is not an appropriate solution, as
these procedures are justifiable for numerous reasons related to management, safety, production
and animal welfare. There are currently no alternative options to performing castration and
dehorning, therefore there is a need to incorporate pain relief into routine procedure. Recently, the
practical constraints associated with conventional forms of anaesthesia and analgesia have been
addressed through the development and registration of ‘farmer applied’ pain relief products. A
topical anaesthetic (TA) gel (Tri-Solfen®, Bayer Animal Health Australia) designed to be
absorbed through tissue in open wounds, and a buccal meloxicam (BM) gel (Ilium® Buccalgesic
OTM, Troy Laboratories) designed for oral trans-mucosal absorption, have been developed for
post-operative anaesthesia and analgesia of lambs and calves undergoing surgical husbandry
procedures.
This thesis has aimed to assess the efficacy of TA and BM, singly and in combination, for the
relief of post-operative pain caused by surgical castration and amputation dehorning of calves.
This thesis has also aimed to assess the efficacy of a vapocoolant spray as a practical option for
providing temporary local anaesthesia for alleviation of intra-operative pain during surgical
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castration. This thesis has addressed these aims through experimentation presented as several
studies incorporating multiple methods of pain assessment.
The effect of TA on the cortisol response of unweaned beef calves to surgical castration was
examined for 6 hours following the procedure. Topical anaesthesia did not significantly reduce
plasma cortisol concentration following castration of calves. However, there was a trend for calves
treated with TA to display lower cortisol concentrations than untreated castrated calves.
The effect of TA and BM, singly and combined, on production, behaviour and wound
inflammation of unweaned beef calves following surgical castration, was investigated. Results
suggest that TA and BM, alone and in combination, reduced pain, as demonstrated through a
reduction in some pain-related behaviours. Results indicate that BM reduced inflammation, as
demonstrated through reduced maximum scrotal temperature.
To address the intra-operative pain of surgical castration in calves, the effects of a topical
vapocoolant spray, applied to the scrotum and spermatic cords, and lignocaine injected into the
scrotum and spermatic cords, were assessed. Results show that both the vapocoolant spray and
lignocaine were inadequate to reduce pain during surgical castration of unweaned beef calves, as
calf behaviour during the procedure did not differ from that of untreated, castrated calves.
Mechanical stimulation of wounds, treated with and without various TA formulations, or a cornual
nerve block of lignocaine, was conducted to investigate wound sensitivity following amputation
dehorning of unweaned beef calves. Results indicate that TA formulations were comparable to a
cornual nerve block of lignocaine in their ability to anaesthetise dehorning wounds post-
operatively.
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Behaviour and wound inflammation following amputation dehorning of unweaned beef calves,
with and without treatment with TA or BM, was assessed. There were no clear effects of TA and
BM on pain and inflammation in this study and further work is required.
The effects of TA and BM, singly and combined, on production and behaviour of weaned beef
calves following concurrent castration and dehorning, were examined. A combination of TA and
BM prevented weight loss associated with castration and dehorning and increased lying activity,
thought to be due to a reduction in pain-related restlessness.
In conclusion, results of all studies suggest that TA and BM result in some amelioration of pain
caused by castration and dehorning of calves, with indications of increased efficacy when a
combination of TA and BM is used. The results suggest that TA and BM do not completely abolish
pain following castration and dehorning of calves and therefore further improvements to analgesic
therapies for these procedures should be investigated.
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Table of Contents
Declaration ...................................................................................................................................... 2
Acknowledgements ......................................................................................................................... 3
Abstract ........................................................................................................................................... 6
Table of Contents ............................................................................................................................ 9
List of Figures ............................................................................................................................... 12
List of Tables ................................................................................................................................ 14
List of peer reviewed publications ................................................................................................ 16
List of conference presentations ................................................................................................... 17
List of grants ................................................................................................................................. 19
Thesis style.................................................................................................................................... 20
Disclosure and author contributions ............................................................................................. 21
Abbreviations ................................................................................................................................ 28
CHAPTER 1: LITERATURE REVIEW ...................................................................................... 32
1.1 Introduction ........................................................................................................................ 32
1.2 Welfare of Australian beef cattle ....................................................................................... 33
1.3 The northern Australian beef industry ............................................................................... 35
1.4 Invasive husbandry procedures performed on cattle ......................................................... 37
1.5 Pain pathways and pain mechanisms ................................................................................. 41
1.6 Pain assessment in cattle .................................................................................................... 45
1.7 Analgesic therapies for painful husbandry procedures in cattle ........................................ 67
1.8 Consumer and producer attitudes to animal welfare and pain ........................................... 74
1.9 Summary and research objectives ...................................................................................... 75
CHAPTER 2: EFFECT OF A TOPICAL ANAESTHETIC FORMULATION ON THE
CORTISOL RESPONSE TO SURGICAL CASTRATION OF UNWEANED BEEF CALVES 77
2.1 Abstract .............................................................................................................................. 78
2.2 Implications........................................................................................................................ 79
2.3 Introduction ........................................................................................................................ 79
2.4 Materials and methods ....................................................................................................... 81
2.5 Results ................................................................................................................................ 84
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2.6 Discussion .......................................................................................................................... 86
2.7 Conclusion ......................................................................................................................... 93
2.8 Conflicts of interest ............................................................................................................ 93
2.9 Acknowledgements ............................................................................................................ 93
CHAPTER 3: EFFECTS OF TOPICAL ANAESTHESIA AND BUCCAL MELOXICAM
TREATMENTS ON PRODUCTION, BEHAVIOUR AND INFLAMMATION OF
UNWEANED BEEF CALVES FOLLOWING SURGICAL CASTRATION ............................ 94
3.1 Abstract .............................................................................................................................. 95
3.2 Implications........................................................................................................................ 96
3.3 Introduction ........................................................................................................................ 96
3.4 Materials and methods ....................................................................................................... 98
3.4 Results .............................................................................................................................. 108
3.5 Discussion ........................................................................................................................ 112
3.6 Conflicts of interest .......................................................................................................... 117
3.7 Acknowledgements .......................................................................................................... 118
CHAPTER 4: EFFECT OF LIGNOCAINE OR A TOPICAL VAPOCOOLANT SPRAY ON
THE PAIN RESPONSE TO SURGICAL CASTRATION IN BEEF CALVES ....................... 119
4.1 Abstract ............................................................................................................................ 120
4.2 Introduction ...................................................................................................................... 121
4.3 Materials and methods ..................................................................................................... 122
4.4 Results .............................................................................................................................. 126
4.5 Discussion ........................................................................................................................ 130
4.6 Conflicts of interest .......................................................................................................... 136
4.7 Acknowledgements .......................................................................................................... 136
CHAPTER 5: EFFECT OF TOPICALLY APPLIED ANAESTHETIC FORMULATION ON
THE SENSITIVITY OF SCOOP DEHORNING WOUNDS IN CALVES .............................. 137
5.1 Abstract ............................................................................................................................ 138
5.2 Introduction ...................................................................................................................... 139
5.3 Materials and methods ..................................................................................................... 140
5.4 Results .............................................................................................................................. 146
5.5 Discussion ........................................................................................................................ 151
5.6 Conflicts of interest .......................................................................................................... 155
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