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:
Avian inflammation and nutritional disorders
Pathology of bacterial, viral, fungal, parasitic, chlamydial, spirochaetal, and mycoplasmal infections
Vices and miscellaneous disease conditions
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.
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
