This comprehensive resource delves into the diverse aspects of pathology, covering a wide range of diseases affecting various organisms. Topics include the pathology of viral, prion, bacterial, mycoplasma, chlamydial, fungal, and parasitic diseases, providing insights into their causes, progression, and impacts on health. The book also addresses pathology related to nutritional imbalances, toxicopathology, and diseases specific to laboratory and wild animals. By integrating detailed studies across these areas, it serves as a valuable guide for understanding disease mechanisms and their implications, catering to students, researchers, and professionals in pathology and related fields.
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) 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 “Special Veterinary Pathology (Pathology of infectious and non-infectious diseases of domestic, pet, laboratory and wild animals)” 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 animal population. However, students of Veterinary Science desire a compact text of Special Veterinary Pathology (Pathology of infectious and non-infectious diseases of domestic, pet, laboratory and wild animals) 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 Special Veterinary Pathology (Pathology of infectious and non-infectious diseases of domestic, pet, laboratory and wild animals) at undergraduate and postgraduate level and are interested in any kind of competitive examination or interview. It covers all the topics of Pathology of infectious and non-infectious diseases of domestic, pet, laboratory and wild animals.
Foot and Mouth disease Foot and mouth disease is a contagious viral disease of cloven footed animals caused by a picorna virus and characterized by presence of vesicles in oral mucosa and foot (Fig.1.1). Etiology • RNA virus of picornaviridae family • Picorna virus • Serotypes A,O,C, SAT-1, SAT-2, SAT-3, Asia-1, serotype ‘O’ is most common in India. Pathogenesis Inhalation is the main route of infection in ruminants; however, ingestion of contaminated feed and water, inoculation of contaminated vaccines, insemination with contaminated semen and contact with fomites such as clothing, instruments etc. may also transmit the infection. When animal gets infected through respiratory tract, viral replication starts in pharynx followed by viraemic spread to other tissues and organs like epithelium of mouth. Viral excretion commences about 24 hours prior to the onset of clinical form of disease and continues for several days. The aerosols of infected animals contain large amount of virus particularly of swine. Large amount of virus is excreted in milk. In cattle and sheep, virus may be detectable up to 2 years and 6 months of exposure, respectively.
Tuberculosis Tuberculosis is a chronic bacterial disease of cattle, buffaloes, sheep, goat and pigs caused by Mycobacterium sp. and characterized by presence of tubercle nodules in lungs, spleen and lymph nodes (Fig.2.1). Etiology • Mycobacterium tuberculosis • M. bovis Pathogenesis Disease spreads through contact with infected animals or their discharges or morbid tissues. The infected animals release the organisms through sputum at coughing and contact animals get infection through droplet inhalation.Besides sputum, faeces, urine, vaginal discharges, semen, milk, lymph and wound discharges may act source of infection. It is also transmitted through contaminated instruments, utensils and beddings. After entry through inhalation or ingestion, bacilli localizes at the point of entry and produce typical tubercle in associated lymph nodes. Mostly pharyngeal and mesenteric lymph nodes are affected. From lymph nodes, infection may extend across body cavities, blood vessels and lymph vessels. The inhaled organism enter in the bronchial tree after lodging in bronchi a tissue reaction takes place. Neutrophilic infiltration is there and when neutrophils are necrosed, macrophages come to destroy the organism but they fail then many macrophages becomes elongated to form epithelioid cells, the hall mark of granulomatous inflammation. Some macrophages are joint together to form giant cells to destroy the acid fast bacilli. As a consequence of this some bacilli are phagocytosed and are destroyed. A zone of lymphocytes, macrophages, epithelioid cells, giant cells and fibrous connective tissues are formed around the central necrosed area.
Chlamydiosis Chlamydiosis is an infectious disease of animals caused by Chlamydia sp. and characterized by encephalitis, polyarthritis and pneumonia in calves and abortions in cows and sheep. Etiology • Chlamydia psittacii Pathogenesis Chlamydial infection spreads through inhalation of contaminated dust from infected birds. Organism multiplies in lungs and through blood it spreads to liver, spleen, kidneys, brain, joints and placenta to cause pathology. Characteristic symptoms Calves • Fever, dyspnoea • Nasal discharge, hypersalivation • Swelling of joints
Anaplasmosis Anaplasmosis is an infectious disease of animals caused by a rickettsia and characterized by icterus, enlargement of spleen, pale tissues, thin watery blood and petechiae over serous membranes (Fig.4.1). Etiology • Anaplasma centrate • A. marginale • A. ovis Pathogenesis The disease is transmitted through bite of tick (Boophilus), biting flies (Tabanus) and also in some cases due to mosquitoes. It is intra cellular organism and multiplies inside the erythrocytes by binary fission. The infected erythrocytes are engulfed by the cells of reticuloendothelial system (spleen, bone marrow). The process of erythrophagocytosis cause extra vascular haemolysis leading to anemia. It also causes autoimmune reaction leading to lysis of erythrocytes.
Contagious Bovine Pleuropneumonia (CBPP) Contagious bovine pleuropneumonia (CBPP) is an infectious disease of cattle caused by Mycoplasma sp. and characterized by cuprous pneumonia, pleurisy and dilation of lymph vessels (Fig.5.1). Etiology • Mycoplasma mycoides Pathogenesis The infection spreads through inhalation of droplets from infected animals. The recovered animals act as source of infection at least for a period of 3 years. After entering through respiratory tract the organism reaches to bronchioles. It may remain in retropharyngeal gland from where it may spread in whole body. The organism from bronchioles enter into interlobular septa and causes inflammation followed by edema which causes dilation and subsequent thrombosis of lymph and blood vessels prior to development of pneumonic lesions. Death occurs due to anoxia and toxaemia.
Leptospirosis Leptospirosis is an infectious disease of animals caused by spirocheate Leptospria sp. and characterized by widespread haemorrhage in visceral organs, nephritis, icterus, hepatitis and anemia (Fig.6.1). Etiology • Leptospira ictehaemorrhagae • L. pomona Pathogenesis The organism is transmitted through direct contact with urine of infected animals or ingestion of urine contaminated feed or water. It can also be transmitted through aborted fetuses and infected uterine discharges. The organism enters through abraded skin and mucous membrane and reaches in blood and multiplies rapidly in blood producing septicemia and high rise in body temperature. Thereafter the organism localizes in the kidneys leading to acute or chronic nephritis. In kidneys, it multiplies in proximal convoluted tubules (PCT) and is excreted in urine which acts as source of infection.
Spongiform encephalopathy Spongiform encephalopathy is an infectious disease of animals caused by prion proteins and characterized by presence of vacuoles in brain. Etiology • Prion proteins • Sheep – Scrapie or Ovine spongiform encephalopathy • Cattle - Bovine spongiform encephalopathy (Mad cow disease) • Feline encephalopathy Pathogenesis Scrapie is also known as ovine spongiform encephalopathy. The principle means of transmission of disease is from infected mother to their lambs early in life; placental transmission has also been reported. The incubation period of disease is very long (2-5 year). The clinical form is restricted in adults. The prion proteins (PrP) occur normally in the central nervous system of all domestic animals and man bounded with neuronal surface. Animal susceptible to prion disease have a gene (PrP gene) which encodes for normal “Prion protein (PrP)” or “cellular prion protein (PrPc). In scrapie prion protein (PrPsc)/ scrapie associated fibril protein (SAI) is generated which are resistant for protease digestion. Accumulation of PrPsc in neural tissues appears to be the cause of the pathology in prion disease. When prion protein contaminated meat and bone meal are fed to the cattle as part of their concentration, the agent (prion) got introduced into cattle. Prion protein (PrP) on reaching brain slowly and progressively converted into and abnormal form (PrP sc) and this abnormal protein causes development of lesions including vacuolation in nerve cells.
Ringworm Ringworm is a fungal disease of skin affecting animals characterized by popular skin lesions in circular form discharging serus exudate. Etiology • Microsporum canis- dogs • M. gypseum- dogs, horse, pig • Trichophyton verrucosum- bovines • T. equinum- horses Pathogenesis The fungi enter in skin through abrasion and the hyphae appear in stratum corneum after germination and invade the hair follicles. The hyphae growth and spore formation in stratum corneum leads to hyperkeratosis and the fungus spreads centrifugally from the point of primary invasion leading to ring shaped lesion (Fig.8.1).
Trypanosomosis Trypanosomosis is an infectious disease of animals caused by protozoan parasite and characterized by emaciation, enlargement of spleen and lymph nodes, petechiae on serous membranes, ulceration on tongue and gastric mucosa and gelatinous exudate in subcutaneous region. Etiology • Trypanosoma evansi Pathogenesis The disease is mainly transmitted through bite of flies like Tabanus, Stomoxys, Haematopota etc. The carrier animals remain as potential source of infection. The pathogenesis of disease is not completely known. After entering in mammalian host, trypanosomes multiply in blood stream by binary fission leading to parasitaenia. The parasites has variable surface glycoproteins which cause continuous exposure of immune system leading to hyperplasia of spleen and lymph nodes. In chronic cases, due to formation of antigen- antibody complexes glomerulonephritis and vasculitis is seen.
Equine Rhabdomyolysis It is also known as Azoturia or Monday Morning Disease. The disease occurs in well fed horse after a spell of inactivity. Suddenly after walking a few steps, the horse is unable to move further and feels pain with intense sweating and hardening of muscles. Etiology • Accumulation of lactic acid in muscles. • High glycogen storage. • Lack of oxygen supply.
Cyanide poisoning Cyanide poisoning occurs in animals due to sorghum and/or other chemicals and characterized by ataxia, incoordination, cystitis, paralysis, and death. Etiology • Sorghum – drought resistant varieties. • Fumigants, fertilizers, • Pesticides. • Industrial leakage/waste, electroplating. • Photographic processes.
Tyzzer’s disease Tyzzer’s disease is an acute infectious disease of laboratory animals including rats caused by Clostridium spp and Characterized by watery diarrhoea, necrotic hepatitis and death Etiology • Clostridium piliforme • Gram positive, Spore forming, Anaerobe Pathogenesis • Horizontal transmission- faecal oral route • Contaminated feed, water • Bacteria in gut causing enteritis
Feline Leukemia Feline leukemia is an infectious viral disease of cats, lion, tiger etc. caused by oncorna virus and characterized by malignant lymphoma, lymphocytosis and immunosuppression. It is also known as feline lymphoma or feline lymphosarcoma. Etiology • Oncorna virus of retroviridae family • Type C oncorna virus, RNA virus has reverse transcriptase Pathogenesis The virus is transmitted horizontally through salivary and nasal secretions of sick cats. It affects lymphocytes causing their proliferation leading to production of neoplastic growth. Characteristic symptoms • Enlargement of superficial lymph nodes • Lymphocytosis • Chronic diarrhoea • Abortion
Abdomen 13, 39, 43, 44, 53, 54, 75, 131, 135, 208, 236, 249 Abdominal 45, 54, 161, 163, 168, 171, 196, 225 Abndance 200 Abnormal 119, 157, 198, 201, 206, 207, 208, 233 Abnormalities 224 Abomasal 28, 72, 73, 264, 265 Abomasitis 26, 72, 182, 264 Abomasum 10, 11, 29, 31, 32, 71, 72, 73, 93, 142, 143, 159, 160, 182, 183, 209, 220, 264, 265, 269, 270 Aborted 16, 18, 48, 65, 79, 98, 117, 126, 265 Abortion 17, 45, 46, 47, 48, 57, 64, 65, 76, 86, 95, 97, 98, 103, 104, 113, 118, 122, 123, 125, 126, 132, 146, 147, 152, 241, 242, 251
