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 patient (animal) can’t speak his/her illness to the doctor. Keeping the need of study of Veterinary Pathology to become a good Veterinary doctor, book “General Veterinary Pathology and Oncology” is written for the use of teachers, students and field veterinarians. The complexity of the subject was presented in a simplified way particularly keeping the view of Indian geo climatic conditions and animal population. However, students of Veterinary Science desire a compact text of General Veterinary Pathology and Oncology covering the VCI new syllabus of Pathology which can be utilized during their study and examinations particularly competitive examinations. Hence, this text book is prepared as a text material to all those who want to study Pathology at undergraduate and postgraduate level and is interested in any kind of competitive examination or interview. It covers all the topics of Veterinary General Veterinary Pathology like etiology, disturbances in circulation, cell metabolism, growth and pigment metabolism besides inflammation, immunity and immunopathology. Animal cancers are discussed in detail with their occurrence in India, carcinogenesis, staging and grading, diagnosis and prognosis. The text is described in a very simple format including definition, etiology, clinical manifestations, macroscopic and microscopic features and diagnosis and only salient features are mentioned avoiding detailed text. Hope this book “Veterinary General Pathology and Oncology” will find a place in the young fraternity of Veterinary Science. 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.

Definitions Pathology Pathology is the study of the anatomical, chemical and physiological alterations from normal as a result of disease in animals. It is a key subject because it forms a vital bridge between preclinical sciences (Anatomy, Physiology, Biochemistry) and clinical branches of Medicine and Surgery (Fig.1.1). Pathology is derived from the Greek word pathos = disease, logos = study. It has many branches, which are defined as under: General Pathology General Pathology concerns with basic alterations of tissues as a result of disease. e.g. fatty changes, thrombosis, amyloidosis, embolism, necrosis (Fig. 1.2). Systemic Pathology Systemic Pathology deals with alterations in tissues/organs of a particular system. e.g. respiratory system, genital system etc. (Fig. 1.3).

Etiology Etiology is the study of cause of disease. It gives precise causal diagnosis of any disease. Broadly, the cause of diseases can be divided into two a. Intrinsic causes. b. Extrinsic causes. Intrinsic Causes Those causes which determine the type of disease present within an individual over which he has no control. These causes are further divided into following subgroups: Genus Specific diseases occur in a particular genus or species of animals. e.g. Hog cholera in pigs, Canine distemper in dogs

Congestion/ Hyperemia Hyperemia is increased amount of blood in circulatory system. It is of two types, active and passive. In active hyperemia blood accumulates in arteries while in passive hyperemia the amount of blood increases in veins (Figs. 3.1. to 3.4). Etiology • As a result of inflammation. • Obstruction of blood vessels. Macroscopic features • Organ becomes dark red/cyanotic. • Size of organ increases.

Cloudy Swelling Swelling of cells occur with hazy appearance due to a mild injury. The cells take more water due to defect in sodium pump leading to swollen mitochondria which gives granular cytoplasmic appearance. It is the first reaction of cell to the mildest injury. Cloudy swelling is a reversible reaction (Figs. 4.1 & 4. 2). Etiology • Can be caused by even mildest injury. • Any factor causing interference with metabolism of the cell like bacterial toxins, fever, diabetes, circulatory disturbances etc. Macroscopic features • Organ becomes enlarged and rounded. • Weight of organ increases. • Bulging on cut surfaces. • Amount of fluid increases in organ. Microscopic features • Swelling of cells, edges become rounded. • Increased size of cells. • Cytoplasm of the cells becomes hazy/cloudy due to increased granularity. • Can be seen in liver, kidney and muscles.

Necrosis Local death of tissue /cells in living body is known as necrosis, It is characterized by the followings. • Pyknosis is condensation of chromatin material, nuclei become dark, reduced in size and deeply stained. • Karyorrhexis is fragmentation of nucleus. • Karyolysis is dissolution of nucleus into small fragments, basophilic granules/fragments. • Chromatolysis is lysis of chromatin material. • Necrobiosis is physiological cell death after completion of its function e.g. RBC after 140 days. Necrosis is further classified into coagulative, caseative, liquifactive and fat necrosis which are different from apoptosis (Figs. 5.1 to 5.3).

Inflammation Inflammation is a complex process of vascular and cellular alterations that occur in body in response to injury. The term inflammation has been derived from the Latin word inflammare, means to set on fire. Inflammation is considered as an important event in body that activates the existing defense mechanisms in circulating blood to dilute, naturalize or kill the irritant/ causative agent. Thus, it is said that immunity is the resistance of body, while inflammation is the activation of that immunity. It is beneficial to body except when chronic or immune origin. Inflammation starts with sublethal injury and ends with healing. Etiology • Any irritant/ injury. • Bacteria, virus, parasite, fungus etc. • Trauma. • Physical or chemical injury.

Immunity Immunity is the resistance of body against extraneous etiological factors of disease, which is afforded by the interaction of chemical, humoral and cellular reactions in body. This is an integral part of the body without, which one cannot think of life. During the process of evolution, nature has provided this defense mechanism in the bodies of all living creatures particularly of higher animals and man, that protects them from physical, chemical and biological threats. It can be classified as natural or paraspecific and acquired or specific immunity. Natural/paraspecific immunity There are some species which are resistant to particular diseases due to presence of natural resistance against them e.g. horse, pig, cat are resistant to canine distemper virus; dogs are resistant to feline panleucopenia virus, chickens are resistant to anthrax. Even within species, there is natural resistance that protects some individuals while others are susceptible e.g. Indian deshi cattle Zebu (Bos indicus) is quite resistant to piroplasmosis in comparison to Bos taurus. Besides, there are the mechanisms or barriers in body provided by nature.

Calcification Calcification is the deposition of calcium phosphates and calcium carbonates in soft tissues other than bones and teeth. It may be classified as dystrophic and metastatic calcification. Dystrophic Calcification Dystrophic calcification is characterized by the deposits of calcium salts in necrosed tissue of any organ (Fig 8.1). Etiology /Occurrence • Necrosis. • Parasitic infections. • Tuberculous lesions.

Aplasia/Agenesis Aplasia or agenesis is absence of any organ (Fig. 9.1). Hypoplasia Hypoplasia is failure of an organ/tissue to attain its full size (Fig. 9.1). Etiology • Congenital anomalies e.g. hypoplasia of kidneys in calves. • Inadequate innervation. • Inadequate blood supply. • Malnutrition. • Infections e.g. cerebral hypoplasia in bovine viral diarrhoea.

Concretions Concretions are solid, compact mass of material, endogenous or exogenous in origin, found in tissues, body cavities, ducts or in hollow organs. Concretions are stone-like bodies commonly occur in urinary system, gall bladder and gastrointestinal tract. Concretions of endogenous origin are known as calculi while those formed from exogenous material are known as piliconcretion (Hair), phytoconcretion (plant fibres) and polyconcretion (polythenes). Calculi Calculi are formed due to deposition of salts around the nucleus/nidus consisting of either fibrin, mucus, desquamated epithelial cells or clumps of bacteria. Due to the gradual and repeated precipitation of salts, calculi become laminated. In the process of calculi formation, the inner structural arrangement gets shrink, producing a rough superficial surface. Calculi formation is more common in urinary system and in gall bladder of man and animals; however, they may also occur in salivary gland, pancreas and intestines.

• Neoplasm General • Neoplasm in cattle and buffaloes • Neoplasm in sheep and goat • Neoplasm in equines, swine and camels • Neoplasms in pet animals • Neoplasms in poultry • Neoplasms in wild animals • Neoplasms in laboratory animals

• General Consideration • Post-mortem examination of large animals • Post-mortem examination of poultry • Steps in post-mortem examination • Writing of post-mortem report • Collection, preservation and dispatch of specimens for laboratory diagnosis General Consideration Necropsy is examination of animal after death also known as post mortem examination. It helps in diagnosis of diseases and their control. It is said that “Necropsy is a message of wisdom from dead to living”. Necropsy include systemic examination of dead animal, recording of pathological lesions, their interpretation to make diagnosis of disease. Sometimes it is difficult to arrive any conclusion merely based on gross examination of dead animal. Then one should seek the help of laboratory examinations such as Histopathology, Microbiology, Immunology and Toxicology for confirmation.

A Abomasum 108, 319, 339, 350, 356 Abrachiocephalia 26 Abrasions 30 Abscess 91, 94, 114, 115, 152, 158, 196, 196, 349, 351, 352, 358 Acetoacetate 51 Acetone 51 Acetonemia 51