UNIVERSIDADE DE LISBOA Faculdade de Medicina Veterinária PERFORMANCE EVALUATION IN IRISH RACEHORSES WITH DORSAL DISPLACEMENT OF THE SOFT PALATE FOLLOWING THE LARYNGEAL TIE-FORWARD PROCEDURE RICARDO MAÇARICO BAIÃO CONSTITUIÇÃO DO JÚRI ORIENTADOR Doutora Paula Alexandra Botelho Garcia de Doutor José Paulo Pacheco Sales Luís Andrade Pimenta Tilley CO-ORIENTADOR Doutor José Paulo Pacheco Sales Luís Dr. Turlough Mc Nally Doutora Maria Rita Martins Garcia da Fonseca 2015 LISBOA UNIVERSIDADE DE LISBOA Faculdade de Medicina Veterinária PERFORMANCE EVALUATION IN IRISH RACEHORSES WITH DORSAL DISPLACEMENT OF THE SOFT PALATE FOLLOWING THE LARYNGEAL TIE-FORWARD PROCEDURE RICARDO MAÇARICO BAIÃO DISSERTAÇÃO DE MESTRADO INTEGRADO EM MEDICINA VETERINÁRIA CONSTITUIÇÃO DO JÚRI ORIENTADOR Doutora Paula Alexandra Botelho Garcia de Doutor José Paulo Pacheco Sales Luís Andrade Pimenta Tilley CO-ORIENTADOR Doutor José Paulo Pacheco Sales Luís Dr. Turlough Mc Nally Doutora Maria Rita Martins Garcia da Fonseca 2015 LISBOA I dedicate this work to my father who hasn’t had the chance to see me finish it. i ii Acknowledgments This is the final step from a journey that I choose to be my life. During this journey, many people positively interfered, so here is my acknowledgment to all of them. Firstly, to my parents that always encouraged me to follow my dream and made everything possible for me to achieve it. I need to make a special reference to my father that made me the man I am today and always wanted me to be successful, so this is for you. Secondly, to Doctor Turlough Mc Nally, my co-supervisor, for accepting me at Anglesey Lodge Equine Hospital and for setting a great example of professionalism. I am really grateful for all the help with this work. It was an honor. To Prof. Doctor José Paulo Pacheco Sales Luís, my supervisor, for supervising my work and for creating the enthusiasm that I have now for surgery. To all my family, for supporting me along the way and gave me the strength that was decisive to finish this work. To Carolina Temtem (a.k.a Mamã Coirão) for supporting my decisions and for being there as a true friend helping me every time I needed. To all my friends at Almeirim, especially Inês and “Toon” for all the good advices along these six years. To Doctor Paula Tilley for all the knowledge transmitted during my training period at Equine Hospital, Faculty of Veterinary Medicine, University of Lisbon (FMV-ULisboa) and along the degree. To Dr. Joana Simões and Dr. Adriana Alberto for welcoming me at Equine Hospital, Faculty of Veterinary Medicine, University of Lisbon (FMV-ULisboa) and made me feel part of the team. To all the remaining staff at Anglesey Lodge Equine Hospital, especially to Kirsty who received me at her home and made me feel at home in Ireland during the training period. Also to Dr. Telmo Nunes for all the patience and help during the statistical analysis of this work. Without your help the results of this work would never be possible. iii iv Abstract Performance evaluation in Irish racehorses with dorsal displacement of the soft palate following the laryngeal tie-forward procedure The horse races are a very important money income in Ireland, being required that the racehorses show the full potential at the races. The dorsal displacement of the soft palate (DDSP) is a common cause of poor performance and exercise intolerance in racehorses being the laryngeal tie-forward procedure the surgical technique with the highest success rate on the correction of this condition. A performance evaluation study was performed to evaluate the significance of the laryngeal tie-forward procedure for correction of DDSP in racehorses. The race performance data was collected for the horses (n = 16) and the effect of surgery on racing performance, the effect of recovery time in earnings and the difference of the earnings by sex and age were analyzed. The racing performance improves after surgery (P = 0,0138), with an increase in the earnings three times the baseline value four races after surgery. The laryngeal tie-forward procedure corrects DDSP, increasing the race performance above the baseline value. Key words: racehorses, DDSP, race performance, laryngeal tie-forward, earnings. v vi Resumo Avaliação da performance desportiva em cavalos de corrida irlandeses com deslocamento dorsal do palato mole após a realização de cirurgia para movimento rostral da laringe As corridas de cavalos são uma grande fonte de riqueza na Irlanda, sendo importante que os cavalos de corrida apresentem o potencial máximo durante as corridas. O deslocamento dorsal do palato (DDP) é uma causa comum de diminuição da performance e de intolerância ao exercício em cavalos de corrida, sendo a cirurgia para movimento rostral da laringe a técnica cirúrgica com maior taxa de sucesso no tratamento desta condição. Foi realizado um estudo para avaliar a significância da cirurgia para movimento rostral da laringe para correção de DDP na performance desportiva. Os dados da performance desportiva foram recolhidos para todos os cavalos (n = 16) e foi analisado o efeito da cirurgia na performance desportiva, o efeito do tempo de recuperação nos ganhos monetários e a diferença dos ganhos monetários por género e idade. A performance desportiva melhora após a cirurgia (P = 0,0138), aumentando os ganhos monetários três vezes o valor base, quatro corridas após a cirurgia. A cirurgia para movimento rostral da laringe corrige o DDP, aumentando a performance desportiva para valores superiores ao valor base. Palavras-chave: cavalos de corrida, DDP, performance desportiva, movimento rostral da laringe, ganhos monetários. vii viii Table of Contents Acknowledgments .................................................................................................................. iii Abstract ................................................................................................................................. v Resumo ................................................................................................................................ vii Training period activities ........................................................................................................ 1 1. Introduction ........................................................................................................................ 4 2. Literature Review ............................................................................................................... 5 2.1. Pharynx ....................................................................................................................... 5 2.1.1. Functional anatomy of the pharynx ....................................................................... 5 2.1.1.1. Intrinsic muscles of the nasopharynx ............................................................... 8 2.1.1.2. Extrinsic muscles of the nasopharynx .............................................................. 9 2.2. Dorsal displacement of the soft palate (DDSP) .......................................................... 11 2.2.1. Etiology ............................................................................................................... 11 2.2.2. History and clinical signs ..................................................................................... 14 2.2.3 Diagnosis ............................................................................................................. 14 2.2.4. Treatment ........................................................................................................... 16 2.2.4.1. Non surgical management of DDSP .............................................................. 16 2.2.4.2. Surgical management of DDSP ..................................................................... 18 2.2.4.2.1. Laryngeal tie-forward procedure .............................................................. 18 2.2.4.2.2. Staphylectomy ......................................................................................... 22 2.2.4.2.3. Standard myectomy ................................................................................ 23 2.2.4.2.4. Minimally invasive myectomy .................................................................. 24 3. Study: Performance evaluation in Irish racehorses with dorsal displacement of the soft palate following the laryngeal tie-forward procedure ............................................................ 25 3.1. Introduction and Main Objective ................................................................................ 25 3.2. Material and Methods ................................................................................................ 25 3.2.1. Study design, population and eligibility criteria .................................................... 25 3.2.2. Surgical technique .............................................................................................. 25 3.2.3. Performance data ............................................................................................... 26 3.2.4. Control selection ................................................................................................. 26 3.2.5. Statistical analysis and reporting ......................................................................... 26 3.3. Results ...................................................................................................................... 27 3.3.1. Population ........................................................................................................... 27 3.3.2.