AVIAN PATHOLOGY
authored by: R.S. Chauhan & Desh Deepak Singh
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Avian Pathology is a comprehensive yet concise guide that bridges the gap between basic and clinical veterinary sciences, with a specific focus on avian species. Given that birds cannot verbally express their illness, the role of pathology becomes essential for accurate diagnosis and effective clinical decision-making.
This book is designed for veterinary students, educators, and field veterinarians, offering a well-structured and accessible resource that supports both learning and practice. The subject matter is presented in a simplified and focused format, with particular consideration for India’s diverse geo-climatic conditions and its substantial poultry population.
The text covers a wide range of important topics including:
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Avian inflammation and nutritional disorders
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Pathology of bacterial, viral, fungal, parasitic, chlamydial, spirochaetal, and mycoplasmal infections
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Vices and miscellaneous disease conditions
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Etiology, clinical signs, characteristic gross and microscopic lesions, and key diagnostic features
By emphasizing salient pathological features and minimizing overly detailed descriptions, the book offers clarity and practicality for readers. It is especially useful for those involved in field diagnosis, disease investigation, and post-mortem reporting in poultry.
Avian Pathology serves as a vital resource for anyone involved in avian health care and disease management. It is expected to find a valued place within the academic and professional community of veterinary sciences.
Prof RS Chauhan: – COWPATHY MAN MVSc, PhD, FNAVS, FSIIP, FIAVP, Diplomat ICVP, PDCR, ACPPM, OCTT, MBA EX- Director ICAR-IVRI, JD CADRAD, Director IBT, National Fellow, Advisor WHO. Member, Animal Welfare Board of India; Member, CPCSEA ( Govt. of India); Chairman, Scientific Advisory Committee, ICMR-NARFBR. Born on September 10th, 1958 in a farmer's family, Dr. Chauhan completed his Bachelors (80.3%) with honours, Master (85.8%) and Doctoral degree (90.0%) in Veterinary Sciences with specialization in veterinary pathology from G.B. Pant University of Agric. & Tech., Pantnagar. He served the country in various capacities including Assistant Professor/ADIO (1983-96), Associate Professor (1996-1999), National Fellow (1999-2004) and Joint Director (CADRAD), IVRI, Izatnagar(2004-2009), Director & Vice-Chancellor(2009), ICAR-IVRI and Campus Director, IBT, Patwadangar (2009-2013). During his tenure as academician and scientist, he has written 112 books including 35 manuals and 1 monograph very popular among the students world over. He contributed 99 chapters in different books and published 235 research and 59 review papers. Besides, he participated in International / National Conferences and presented 178 papers. He is life member of 15 scientific bodies and has been in several executive committee such as Chairman, Panch Gavya Professionals’ Club; President, Cow Therapy Society; Secretary-General, Society for Immunology and Immunopathology; Vice President, Indian Society of Veterinary Educators; Zonal Secretary, Indian Association of Veterinary Pathologists and Joint Secretary, Indian Virology Society, President, Dr. J.L. Vegad Foundation, Expert Member Research Group, Committee for Certification of Pathologists, Vice-President, IAVP; Registrar, ICVP, etc.
Based on his contributions and scientific achievements, he has been awarded with several prizes, medals and honours including Best Young Scientist Award (1992), IAAVR Award (1996), National Fellow Award (1999), Fellow NAVS (2000), Fellow SIIP (2001), K.S. Nair Memorial Award (1999), Vigyan Bharti Award (2000), Dr. C.M. Singh Trust Award (2002), Dr. Rajendra Prasad Award (2002), Shri Ramlal Agrawal National Award (2000), Best Paper Award SIIP (2003), Best Paper Award IAVA (2001, 2002, 2003), Best Teacher Award (2004) by GBPUAT, Fellow, IAVP (2006), Gopal Gaurav (2007), Bharat Excellence Award (2007), Diplomat, ICVP (2008), Intas-ISVE Best Veterinary Scientist Award (2008), Best Academician Award (2012), Moropant Pingle Go Sewa National Award (2015), Outstanding Scientist Award (2019), Research Excellence Award (2020), Indo Asian-Claude Bourgelat Distinguished Innovative Scientist Award-2020 in Animal Immunopathology and MAN OF COWPATHY at GADVASU Ludhiana etc. in recognition of his research and teaching endeavor. He has been inducted in many national and international scientific/advisory committees and boards including Member, WHO/IPCS Committee on Environmental Health Criteria. Dr. Chauhan added many new including Enterotoxaemia, Pyometra, ETEC infection in camels, isolated camel pox virus, developed rapid diagnostic test DIA for the first time in India. He reported role of cell mediated immunity in rotavirus infection in calves. His pioneer work includes immunopathology due to pesticides, heavy metals, mycotoxins and nanoparticles. Dr. Chauhan developed a new method using MTT dye for detection of CMI response. He has scientifically validated Panchgavya and named it as “Cowpathy”.
He have been recognized internationally as visiting Professor, University of Wageningen and Advisor, WHO. Dr. Chauhan guided more than 50 scholars for their Masters and Doctoral research; most of them are placed as Professors, Scientists, Officers in Indian Army, banks and industry in India and abroad. At present he is working as Head Veterinary Pathology, Chairman Scientific Advisory Committee ICMR-NARFBR, Member AWBI and CPCSEA (Govt of India). Prof Chauhan superannuated on 30th June 2024 after distinguish service of 41.5 years and still contributing to the profession through lectures, writings and research and particularly developing literature/ books for the benefit of students and young generation.
Desh Deepak Singh: is Veterinary Graduate and Post Graduate in Veterinary Pathology from Govind Ballabh Pant University of Agriculture and Technology (GBPUA&T), Pantnagar (Uttarakhand) India in 2001 and 2003. He is awarded outstanding student award by GBPUA&T, Pantnagar in 2003. He visited Istanbul, Turkey to present research paper in world poultry congress-2004. He joined as Assistant Professor, Department of Veterinary Pathology, College of Veterinary Sciences & Animal Husbandry, Acharya Narendra Dev University of Agriculture & Technology (ANDUA&T), Kumarganj, Ayodhya, Uttar Pradesh in 2004. He completed his Ph.D. as in-service candidate from Uttar Pradesh Pandit Deen Dayal Upadhyay Pashu Chikitsha Vigyan Vishwavidyalaya Evam Go Anusandhan Sansthan (DUVASU), Mathura-281001, Uttar Pradesh, India in 2017 and promoted to Associate Professor in 2017 in ANDUA&T, Kumarganj, Ayodhya. Dr Singh is selected as Professor, Veterinary Pathology, DUVASU, Mathura in 2023 and presently working as Professor & Head, Veterinary Pathology, DUVASU, Mathura. He is having more than 20 years’ experience of teaching Under Graduate (UG) and Post Graduate (PG) courses of Veterinary Pathology along with vast experience of disease diagnosis, research and extension. He has published more than 48 research papers in referred journals, 08 review articles, 10 book chapters, 53 technical/popular articles, 04 laboratory manuals for Under Graduate students, 02 manuals for Veterinary Officers and 01 book. He is awarded Young Scientist award by Society of Immunology and Immunopathology, Prakash best poster award, best paper presentation award by Indian Society of Veterinary Anatomy, best poster award by UP chapter of Indian Society of Veterinary Surgery and best paper award in National Conference held at ANDUA&T, Kumarganj, Ayodhya.
- Avian Inflammation
- Pathology of Nutritional Disorders
- Viral Diseases
- Pathology of Bacterial Diseases
- Path of Chlamydial Disease
- Pathology of Mycoplasmal Diseases
- Pathology of Spirochaetal Disease
- Pathology of Fungal Diseases
- Pathology of Parasitic Diseases
- Pathology of Vices and Miscellaneous Disease Conditions
Veterinary Pathology is an important discipline of Veterinary Sciences which makes a bridge in between the basic and clinical sciences. The knowledge of Veterinary Pathology makes the Veterinarian a perfect diagnostician particularly when his patients (animal and birds) can’t speak their illness to the doctor. Keeping in view the need of study of Veterinary Pathology to become a good Veterinary doctor, the book “Avian Pathology” is written for the use of teachers, students and field veterinarians. The complexity of the subject is presented in a simplified way particularly keeping the view of Indian geo-climatic conditions and poultry population. However, students of Veterinary Science desire a compact text of Avian Pathology covering the VCI new syllabus of pathology which can be utilized during their study and examinations particularly in competitive examinations. Hence, this textbook is prepared as a text material to all those who want to know Avian Pathology at undergraduate and postgraduate level and are interested in any kind of competitive examination or interview. It covers all the topics of pathology of avian diseases. The text is described in a very simple format including avian inflammation; nutritional disorders; pathology of bacterial; viral; fungal; parasitic chlamydial; spirochaetal; mycoplasmal diseases along with vices and miscellaneous disease conditions with their etiology, clinical manifestations, characteristic macroscopic and microscopic features along with diagnosis; only salient features are mentioned avoiding detailed text. Hope this book “Avian Pathology” not only will find a place in the young fraternity of Veterinary Science but also it will be highly useful to the field Veterinarians for diagnosing diseases on the basis of characteristic clinical manifestations, and lesions and in writing of post mortem report of poultry. The help rendered by our colleagues and students in preparation and designing of this book is duly acknowledged. Readers’ comments are welcome to further improve the book.
• Avian Inflammation Inflammation is a process which begins following a sublethal injury to tissue and ends with complete healing or death. It is characterized by five cardinal signs. Cardinal signs of inflammation are: • Redness • Heat • Swelling • Pain • Loss of function • Inflammation is beneficial in most of cases expect • In prolonged or unending process • In inflammation of immunological origin i.e. hypersensitivity and autoimmunity. • It provides basic foundation of pathogenesis and pathology. • It is now said that immunity is the resistance of body, while inflammation is the process by which the immune mechanism are implemented. • The basis of inflammation remains same be it mammal or birds. For details, one can refer the chapter inflammation and heading in book “Illustrated Veterinary Pathology”. However, there are some differences in reaction in birds which are briefly listed below:
Pathology of nutritional deficiency diseases are described in chapter etiology of this book. However, specific deficiency of nutrition that leads to development of clinical signs and lesions in poultry are summarized as under (Fig.2.1 & Fig.2.2): Vitamin Deficiency 1. Hypovitaminosis A • Vitamin A is considered infection resisting vitamin because it facilitates the proper development of bursa, immunity and epithelium on mucosal and skin surfaces. • Deficiency of vitamin A leads to swollen glands in oesophagus i.e. nutritional roup.
Ranikhet Disease Ranikhet disease is a contagious viral disease of poultry characterized by high mortality petechial hemorrhage in proventriculus, ulcers and hemorrhage at caecal tonsils and pneumoencephalitis. It is also known as Newcastle disease (Fig.3.1). Etiology • Paramyxo virus • RNA virus-3 types • Lentogenic- mild virulent • Mesogenic- moderate virulent • Velogenic- highly virulent
Salmonellosis Salmonellosis is caused by G-bacteria Salmonella and characterized by early chick mortality with necrosis and hemorrhage in liver, heart and spleen and enlarged bronze coloured liver with focal or diffuse necrosis, marbled spleen and/or oophoritis and salpingitis in adults (Fig.4.1). Etiology • Salmonella enteritidis var. Galinarum (S. Galinarum). • G-, rod, non lactose fermenter. • White small colonies on MLA and pink on BGA.
Ornithosis Ornithosis is caused by Chlamydia and characterized by enlargement of liver and spleen, serofibrinous pericarditis, air sacculitis and enteritis. This is also known as chlamydiosis, psittacosis and is more common in parrots, pigeons and other psittacine birds. Etiology • Chlamydia psittaci group B • Size 0.3 to 1.5 m • Disease spreads from wild birds
Chronic Respiratory Disease (CRD) Chronic respiratory disease is caused by Mycoplasma gallisepticum and E.coli in birds under poor management and characterized by cloudy air sacs with thickening of their wall, accumulation of cheesy material in air sacs and lungs (Fig.6.1). Etiology • Mycoplasma gallisepticum • E.coli • Bad management like poor ventilation and inclement weather conditions • Disease occurs more during winter and rainy season.
Spirochetosis Spirochetosis is caused by a spiral shaped organism Borrelia anserina and characterized by greenish diarrhoea, enlarged and mottled spleen, small necrotic patches on liver and linear haemorrhage in proventriculus. This disease is transmitted by a tick Argas persicus and thus also known as “tick fever” or “tick paralysis”. Etiology • Spirochete Borrelia anserina • Spiral shape 8-24m long and 0.2 to 0.3 m wide microorganism having 8-11 spirals. • Stained with aniline dyes
Aspergillosis Aspergillosis is a fungal disease of poultry caused by different species of Aspergillus sp and characterized by granulomatous nodules in lungs, thickening of air sacs and presence of fungal growth in lungs and air sacs in early age of chicks. It is also known as Brooders pneumonia (Fig.8.1). Etiology • Aspergillus fumigatus • A. flavus • A. nidulans • A. glaucus • A. niger • A. candidus
Roundworms (Nematodes) 1. Ascaridia galli A. galli is the common roundworm of poultry seen in intestines at the time of necropsy. This parasite may cause retardation of growth, loss of egg production, catarrhal enteritis and sometimes mortality due to obstruction of gut (Fig.9.1). Etiology • A. galli parasites are grey, thread like 5-10 cm in length. • Eggs are elliptical with thick and shiny wall. Pathogenesis Transmission occurs through faecal - oral route. The eggs may survive for several months in litter and they take at least 10-15 days to develop the infective stage. The eggs of parasites hatch in proventriculus or intestine to develop fully grown parasite within 40-50 days.
Cannibalism Cannibalism is a bad habit of birds in which the birds attack their fellow birds and eat their flesh. It is done through sharp end of beak, which causes deep wounds specially on vent. Sometimes the wounds are so deep that leads to death of affected bird. Two types of cannibalism vices are common i.e. vent pecking and feather pecking. Cause / Predisposing Factors • Over crowding • Genetic predisposition • Hemorrhage in external genitalia • Protein deficiency (arginine and methionine deficiency) • Loss of feathers • Wounds • Prolapse of cloaca
A Accumulation: 2, 70 After: 21, 23, 25, 26, 28, 34, 39, 41, 44, 51, 54, 59, 61, 65, 67 Air: 16, 48, 62, 84 Anemia: 8, 9, 36, 38, 40, 74, 76, 80 Argas: 67, 84 Aspergillus: 69, 70, 75 Atrophy: 7, 21, 33, 36, 38, 41, 55, 56, 75, 76, 98 Aviadenovirus: 36, 38, 39 Avian Influenza: 13, 14 Avian Pathology: 2, 6, 8, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 92, 94, 96, 98
Avian pathology, Poultry diseases, Veterinary pathology, Bird disease diagnosis, Gross lesions in birds, Microscopic lesions in poultry, Avian viral diseases, Bacterial infections in birds,
Fungal diseases in poultry, Parasitic infections in birds, Nutritional disorders in poultry, Chlamydiosis in birds, Mycoplasma infections in poultry, Spirochaetal infections in birds, Clinical signs in avian diseases, Post-mortem findings in birds, Poultry health management, Avian disease symptoms
Pathological features in poultry, Field diagnosis in veterinary medicine