Evaluation of Methods for On-Farm Euthanasia of Commercial Meat Rabbits by Jessica Lindsay Walsh A Thesis presented to The University of Guelph In partial fulfilment of requirements for the degree of Master of Science in Pathobiology Guelph, Ontario, Canada ©Jessica L. Walsh, December, 2016 ABSTRACT EVALUATION OF METHODS FOR ON-FARM EUTHANASIA OF COMMERCIAL MEAT RABBITS Jessica Lindsay Walsh Advisor: University of Guelph, 2016 Dr. Patricia V. Turner There are no validated euthanasia methods for meat rabbits. The goal of this research was to evaluate blunt force trauma (BFT), assisted manual cervical dislocation (AMCD), a non- penetrating captive bolt (NPCB) device and two fill rates of carbon dioxide (CO2) across several age groups of rabbits as methods for on-farm euthanasia. Physical methods were evaluated for their ability to cause immediate sustained insensibility until death occurred. Chamber fill rates for CO2 euthanasia gassing were compared based on signs of distress prior to loss of sensibility, time to insensibility and time to death. A 58% CO2 displacement rate resulted in a significantly shorter time to insensibility and death compared to a 28% displacement rate, with neither rate inducing significant distress behaviours. Our findings indicate that AMCD, a specific NPCB device, and CO2 inhalation at the rates studied are suitable methods for on-farm rabbit euthanasia, while blunt force trauma is ineffective. Acknowledgements First and foremost I would like to thank to my advisor, Patricia Turner, for helping me develop throughout my master’s and polish my skills. Her hours spent editing my work and making sure everything met a professional standard has not gone unappreciated. She went out of her way to make sure I was given opportunities to disseminate our research, and gain useful career skills. Thank-you for helping me obtain the most from my master’s. Thank-you to my committee member, Tina Widowski, for your talented insight and suggestions. This work would not have been possible without the assistance of multiple people that helped me get the study design off the ground; to Penny Lawlis for sharing her industry knowledge and real world applications, to Al Dam for equipment support, and to John Van de Vegte for his engineering skills. I am grateful for the 3 participating commercial meat rabbit producers who welcomed us on farm and were in great compliance and assistance with our research. As well as to my wonderful summer students who took on a difficult task, showing complete dedication to the project; Aaron Percival, Sarah Copeland and Brianne Mercer. I was challenged by my master’s thesis topic of euthanasia in multiple ways. Throughout the past 2 years I was challenged emotionally and ethically to provide the best end of life care. I am grateful to my family and friends for their recognition of this challenge. Their support and reminder of my passion and the positive impact of this research helped me keep moving forward. A special thanks to my mom for always standing by me, and encouraging me to meet my goals. Thanks to everyone that helped me along this journey. Lastly, I would like to thank my funding sources. This project was supported by the Ontario Ministry of Agriculture, Food and Rural Affairs and indirectly by Farm and Food Care. Ontario Rabbit producer group helped form the connections with the industry needed for this research project. Bock Industries donated the NPCB devices used in this research. iii Declaration of Work Performed All the work presented in this thesis was performed by me except for the following: 1. Aaron Percival assisted with data collection and data entry for the physical euthanasia trials (Chapter 2). 2. Survey radiographs were conducted at the OVC Health Sciences Centre (Chapter 2). 3. Brains from rabbits euthanized by physical euthanasia methods were trimmed by Aaron Percival, made into microscope slides by the Animal Health Laboratory, University of Guelph, and then assessed microscopically by a veterinary pathologist, Patricia V. Turner (Chapter 2). 4. Brianne Mercer assisted with data collection and data entry for the gassing trials (Chapter 3). 5. John Van de Vegte (OMAFRA) assisted with design and in vitro testing of equipment for gassing trials (Chapter 3). iv TABLE OF CONTENTS ABSTRACT ................................................................................................................................................................................ ii Acknowledgements .................................................................................................................................................................. iii Declaration of Work Performed .......................................................................................................................................... iv TABLE OF CONTENTS ......................................................................................................................................................... v List of Tables ............................................................................................................................................................................ vii List of Figures.......................................................................................................................................................................... viii Abbreviations ............................................................................................................................................................................... x Chapter 1: Literature Review ................................................................................................................................................. 1 1.1 Introduction ..................................................................................................................................................................... 1 Commercial meat rabbit industry ............................................................................................................................... 1 Euthanasia .......................................................................................................................................................................... 1 1.2 Assessing Insensibility, Degree of Brain Injury, and Time to Death for Euthanasia Methods ............ 2 The brain and consciousness ........................................................................................................................................ 2 Electroencephalogram .................................................................................................................................................... 3 Brainstem and spinal cord reflexes ............................................................................................................................ 4 Physiologic measures ..................................................................................................................................................... 6 Behaviour ........................................................................................................................................................................... 7 Scoring brain damage ..................................................................................................................................................... 8 1.3 Euthanasia Methods and Modes of Action .......................................................................................................... 10 1.31 Physical Methods ................................................................................................................................................. 10 Blunt Force Trauma ...................................................................................................................................................... 10 Cervical Dislocation...................................................................................................................................................... 14 Decapitation ..................................................................................................................................................................... 16 Electrocution ................................................................................................................................................................... 17 Captive Bolt ..................................................................................................................................................................... 18 Penetrating Captive Bolt ............................................................................................................................................. 18 Non-Penetrating Captive Bolt Device ..................................................................................................................... 21 1.32 Inhaled Gasses ....................................................................................................................................................... 24 Carbon Dioxide .............................................................................................................................................................. 25 Carbon Monoxide .......................................................................................................................................................... 28 v Research Goals and Objectives .....................................................................................................................................