GENERAL PATHOLOGY AHT 04107 BY A.NEWTON.

1. GENERAL PATHOLOGYAHT 04107BY A.NEWTON. 1

2. DEFINITIONS: a) General pathology: Is the study of basic alteration in tissues due to diseases. ie, changes involving all body tissues. b) Gross pathology: Is the study of disease in which tissue and organs are examined with an aided eye. c) Pathology: Is the study of functional and morphological changes in tissues and fluids of the body during disease condition. d) Biopsy: Is the removal of a small tissue partical from a living animal. 2

3. e) Health: Is a state of an individual living in complete harmony with its environment. f) Histopathology: Is the study of altered tissue by help of a microscope, usually using stained tissue mounted on glass slides. g) Aetiology: Is the study of causes of disease. h) Pathogenesis: Is the progressive development of disease process from its initiation to its final conclusion. 3

4. i) Necropsy, Autopsy, Postmortem are terms referring to examination of an individual after death by systemic dissection. j) Disease: Is a condition in which an individual shows anatomical or physiological deviation from normal. k) Pathognomonic lesions: Is an alteration that indicates without doubt the cause of particular disease e.g. .Negribodies for Rabies. l) Death: Is the permanent cessation of all biological functions that sustain a living organism. m) Lesion: Is a visible morphological alteration occurring in tissue as a result of injury. 4

5. BRANCHES OF PATHOLOGY a)General pathology :( or Macroscopic or Gross)-Is the study of basic alteration in tissues due to diseases. i.e. changes involving all body tissues. E.g. Anaemia-loss of blood • Jaundice (Icterus)-yellowish discoloration. • Oedema-accumulation of liquids. b) Histopathology: the study of altered tissue by help of a microscope, usually using stained tissue mounted on glass slides. c) Systemic pathology: Study involving systemic examination of an individual system by system.e.g Digestive system etc. 5

6. CAUSES OF PATHOLOGICAL CHANGES They divided into: 1) Intrinsic: factors are characteristics of an individual over which there is no control and determine the type of disease e.g. .Age, sex, e.t.c. 2) Extrinsic: factors are environmental factors capable of producing disease in the individual.e.g. Mechanical, biological etc. 6

7. INTRINSIC CAUSES: i) Genus-the genetically make up of certain species makes them suffer from certain disease and not to suffer from other disease e.g.. Swine fever is specific to pigs, canine distemper is specific to dogs and FMD do not occur in horses. ii) Heredity-some breed of the same species appear to be more susceptible or resistance to certain disease. E.g. Dairy cattle more susceptible than beef cattle. 7

8. iii) Age-young and old animals are more susceptible to certain disease compare to adult ones due to their organ dysfunction and undergrowth/immature. iv) Sex-different sex contributes to different disease due to anatomical variation. E.g. Mastitis and milk fever are disease of cows while prostatic gland, hyperplasia is for males. v) Colour-predispose the animal to photosensitivity. Dark coloured animals absorb more heat than light coloured, hence pigmentation melanosarcomas.  vi) Body conformation-the presence of long sharp horns could increase chances of trauma etc. 8

9. EXTRINSIC CAUSES: i) Environment-some disease are present in certain areas either in soil,water,air or in other animals which are known as reservoirs also similarly condition such as,fatique thirsty traveling may give rise to disease.  ii) Trauma-is a sudden violent physical force which crushes and separates tissues by action of stones, axes, truck or plane crush etc. 9

10. iii) Pathogens-invading pathogens do grow within tissues and fluids causing alterations. These pathogens include: • Bacteria; e.g. Anthrax, Tuberculosis. • Virus; e.g.Rabies,Rinderpest • Worms; e.g.Stelasia hepatica • Fungi; e.g.Tinea pedis • yeast: e.g. • Ectoparasite: e.g.mites. 10

11. GENERAL PATHOLOGICAL CHANGES OCCURING IN THE ANIMAL BODY a) NECROSIS: Is a rapid death of a limited portion of tissues (cells) in a living organism. b) GANGRENE: Is a necrotic area which saprophytic (putrefactive) bacteria has been allowed to grow. Common in the skin, lungs, intestines, limbs ears and mammary glands. c) GENERAL DEATH: Is a cessation to live. It is an irreversible degeneration and an end to all metabolic processes in the body. Death can be physiological or pathological. 11

12. CIRCULATORY DISTURBANCES: i) HYPERAEMIA-refers to an excess of blood in the vessels of a given part/tissue. ii) ANAEMIA-is a reduction in the amount of hemoglobin per unit volume of blood. iii) HAEMORRHAGE-Is the escape of blood from the blood vessel. • By rhesis;when there is a break in the wall of the vessel. • By diapedesis-when blood leaves a vessel through an intarct vascular wall. 12

13. Classification of haemorrhages: • According to location external-occurs on the surface of the body. Internal-blood escapes into the tissues or body cavities. b)According to source of blood Arterial,venous,cardiac.capillary. 13

14. c)According to size and shape; Petechial-are tiny 1-2mm foci Ecchymotic-large areas 2-3cm in size Linear occur in lines on mucus membbrane. Suffusions-occur in lines on membrane,are diffuse,flat irregular shaped areas of blood. 14

15. . • Terminologies Epistaxis-nose bleeding Haemoptysis-spitting blood Haematemesis-vomitting blood Entorrhagia-intestinal haemorrhage Metrorrhagia-uterine bleeding Haematocyst/haematoma-blood collects in spherical shaped mass in the tissues. 15

16. Haematuria-discharging bloody urine Haemothorax-blood in the pleural sac Haematocele-blood in the tunica vaginalis Haemometra-blood in the uterus Purpura-small haemorrhage in the skin,subcutaneous tissue. iv) THROMBOSIS-Is the formation of an intravascular clot from the elements of blood within vascular system. 16

17. v) EMBOLISM; Presence and floating of foreign bodies(emboli)in the blood 17

18. vi) INFARCTION (infarcts); Localize area of necrotic tissue resulting from sudden deprivation of their blood supply. vii) OEDEMA; Is the excessive accumulation of fluid in the intercellular spaces and body cavities, can be localized or generalized. viii) SHOCK; Described as an acute deficiency of flow of blood in the peripheral vascular bed. ix) PIGMENTATION; coloration with or deposition of pigment; especially: an excessive deposition of bodily pigment 18

19. PATHOLOGICAL GROWTH CHANGES; In general terms,disturbance of growth usually involve the following factors; • The number of cells in a tissue or organ • The size of the cells 19

20. A combination of the number & size of the cell and a change from the normal in the relationship of cells and tissue to each other. • Agenesis- tissue or organ does not develop and is absent e.g one kidney might be absent at birth. • Aplasia-organ is present but is markedly reduced in size from normal e.g aplasia of the gonads or one horn of the uterus. 20

21. Atresia-absence or closure of one opening e.g intestinal atresia, if anus is absent (occur in pigs) the lesion is called atresia ani. • Hypoplasia-denotes arrested or incomplete development. • Hperplasia-over growth of a tissue/organ as a result of increased number of cells in a tissue. it can occur due to increased function e.g in thyroid gland with goiter. 21

22. Metaplasia-changing of one kind of tissue into another e.g columnar epithelium into the stratified squamous type or variety, fibrous tissue into bone or cartilage.( transformation/change of a fully normal adult tissue to another related one) 22

23. Atrophy-a decrease in the amount/size of tissue after normal growth has been achieved. • Hypertrophy-increase in size of cell leading to increase in size of tissue. • Apoptosis-death of single cell within clusters of other cells. 23

24. INFLAMMATION Definition: Inflammation is a local response (reaction) of living vascularized tissues to endogenous and exogenous stimuli. • The term is derived from the Latin "inflammare"meaning to burn. Inflammation is fundamentally destined to localize and eliminate the causative agent and to limit tissue injury. 24

25. TYPES OF INFLAMMATION; a)According to the intensity and duration. • -Acute; the reaction is not very severe and a less critical tissue is involved. Persist over period of several days. • -Sub acute; a less intense irritant and less susceptible tissue are involved. Healing occurs after several weeks. • -Chronic; the course of the inflammatory reaction is extremely long for several weeks or months. 25

26. b) According to the nature of exudates (lesions). • -Suppurative/ parulent; Tissue is destroyed and softened with formation of pus.(neutrophils are the major component) Depending on the extent of inflammation,we may further classify this reaction into: • Phlegmon-is a diffuse superative inflammation ,with rapid spread. 26

27. Abscess-is focal,surrounded by an area of acute inflammation with capillaries,leucocytes and connective tissue.Abscess may be: -pastules-if in malphigian layer of epidermis. -furuncles(boil)-if in skin involving hair follicle or subcutaneous gland or sweat gland. 27

28. -carbancle-if in subcutis with general sinuses. Catarrhal/mucous-mild inflammation of the mucous membrane,there is increased secretion of mucous. Serous-the major component is lymph and plasma. Fibrinous/croupous-fibrin is the major component.common in mucous membranes and the lungs in phenomenon. 28

29. Fibrinous/croupous-fibrin is the major component.common in mucous membranes and the lungs in phenomenon. Allergic-reaction of body to a protein to which it has already been sensitized.exudates may be serous,fibrous,suppurative or haemorrhagic. 29

30. -Diphtheric; Inflammation of the mucous membrane of the alimentary tract. The mucosa is necrotic covered by Fibrinous exudates. • -Haemorrhagic; the main features is the presence of large number of erythrocytes in the exudates presenting a reddish or coffee coloured appearance. • -Mixed; e.g.serofibrinous, serohaemorrhagic, mucoparulent,mucohaemorrhagic etc. 30

31. Peracute-is severe involving a very susceptible tissue or organ.the process is rapid and for few hours. Acute-reaction is not very severe and less critical tissue is involved.it persist for over a period of several days. 31

32. Subacute-a less intense irritant and less susceptible tissue is involved .healing occurs after several weeks. Chronic-the cause of the inflammatory reaction is extremely long for several weeks or months. 32

33. c) According to sequelae (consequence) • -Hyperplastic; there is excessive hyperplasia of tissue. • -Hypertrophic; there is an increased size of cells in an inflammatory area. • -Atrophic; results in extensive atrophy of tissue. • -An obliterative; when certain structures e.g. gromerul, blood vessels or bronchi are destroyed by the inflammatory reaction. • -Fibrious; there is excessive proliferation of white fibrous connective tissue in the area. • -Adhesive; adherence of one structure to another by a white fibrous connective tissue. 33

34. According to tissue affected. Pancrease-pancreatitis. Veins-phlebitis Ear-otitis Bone-osteotitis Joint-arthritis Muscle-myositis Penis-balanitis vagina-vaginitis. 34

35. CARDINAL SIGNS OF INFLAMMATION • -Redness (rubor) which is due to dilation of small blood vessels within damaged tissue as it occurs in cellulitis. • -Heat (calore) which results from increased blood flow (hyperemia) due to regional vascular dilation • - Swelling (tumor) which is due to accumulation of fluid in the extra vascular space which, in turn, is due to increased vascular permeability. 35

36. - Pain (dolor), which partly results from the stretching & destruction of tissues due to inflammatory eodema and in part from pus under pressure in as abscess cavity. • - Loss of function: The inflamed area is inhibited by pain while severe swelling may also physically immobilize the tissue. 36

37. CAUSES OF INFLAMMATION • - Physical agents - mechanical injuries, alteration in temperatures and pressure, radiation injuries. • - Chemical agents- including the ever increasing lists of drugs and toxins. • - Biologic agents (infectious) - bacteria, viruses, fungi, parasites • -Immunologic disorders- hypersensitivity reactions, autoimmunity, immunodeficiency. • -Genetic/metabolic disorders- examples gout, diabetes mellitus etc… 37

38. HEALING AND REPAIR DURING THE HEALING PROCESS,damaged cells capable of proliferation regenerate. Different types of cells vary in their ability to regenerate. Some cells, such as epithelial cells, regenerate easily, whereas others, such as livercells, do not normally proliferate but can be stimulated to do so after damage has occurred. Regeneration involves two processes i). Proliferation of surviving cells to replace lost tissue ii). Migration of surviving cells into the vacant space. 38

39. REPAIR, through the repair process, endothelial cells give rise to new blood vessels, and cells called fibroblasts grow to form a loose framework of connective tissue. As repair progresses, new blood vessels establish blood circulation in the healing area, and fibroblasts produce collagenthat imparts mechanical strength to the growing tissue. 39

40. THE PROCEDURE FOR CARRYING OUT POSTMORTEM OF CADAVER HISTORY • When the clinical history concerns before the death of the animal it’s called Anamnesis vitae, when its after death it’s called Anamnesis morbid. • Anamnesis includes ;Knowing species breed,Age,sex colour,owner,Geographic location, when clinical signs started, how many sick and dead if any and the total number of animals in the heard. 40

41. PHYSICAL EXAMINATION i) Examine serous and mucous membranes; see if there is any a colour change or fibrin deposition. ii) Examine skin and its appendages (hooves, horns) by examine the skin coat, colour, thickness and wounds or ulcerations, necrotic areas, abscess and haemorrhage. iii) Examine superficial lymphnodes: should be palpated to know the size, punched to determine the contents 41

42. iv) Examine skeletal muscles; should not growth consistence, Rigor mortis. v) Examine bones and joints; check for any fractures and in joints for quantity and contents of synovial membrane fluids. vi) Check general for other PM changes i.e.Livor mortis (Imbibibition) and state of decomposition. 42

43. DISSECTING (IN CATTLE); • Begins by opening abdominal and thoracic cavities. • Carcass should lay on the left side ie.the rumen being on the ground side. • The limbs both front and behind on the right side are removed, so are the mammary glands or prepuce removed to their roots. • Open the abdominal cavity by cutting a longitudinal cut from the xiphoidea cartilage to the pubis region; make sure no damage of intestines and other visceral organs by directing your knives or scissors by two fingers. 43

44. Remove omentum and observe the position of visceral in relation to each other for excessive fluids. • Opening thoracic cavity begins by cutting the cartilages that connect the ribs to the sternum on the right and those connecting ribs to the thoracic vertebrate. • Then just for abdominal Examination, check the position, contents of organs in the thorax and costal pleural membranes, pericardium is open to see contents 44

45. (IN POULTRY) • After external examination, they should be soaked in water. • Remove some feathers at the neck, thorax region make a mid line incision from towards both anterior and posterior ends. • Detach the legs from their boll-joints partly. 45

46. Open the thorax by cutting the right and left ribs and remove thoracic organs (heart, liver, spleen) then cut by the proventriculus and proceed to remove the rest of digestive system to the cloaca. • Cut on the left side of the mouth cavity from the mouth angle, observe larynx-pharynx region, open trachea. 46

47. OBSERVATION; after this you can be able to see lungs, oviduct ovaries, kidneys which usually remain. • Nervous system is observed by checking the schiatic nerve, and also removing the brain after sagittaly separating the skull by a sharp butcher clever. 47

48. SPECIMEN COLLECTION 1. If you suspect Anthrax. • If not expressing Rigormortis oozing of uncoagulated dark blood from all natural opening e.g. Ears, mouth, anus e.t.c. • -Draw blood from vein the vein in syringe, which you can submit to the laboratory or make thin blood smear and dry in air. 48

49. 2. If you suspect Rabies, take the necessary precautions. • -By being vaccinated against Rabies. • -Wearing gloves and apron. • After extraction of the brain from the suspected animal, put half of the brain in 10% Formalin solution and other half in 50% Glycerol saline solution. 49

50. 3. For Brucellosis (contagious abortion) • -Submit after birth, genital organs or foetus stomach contents. • NB: For all zoonoses cases, the samples should be well packed and be safe to handle. REPORT WRITING/JUDGEMENT: for all PM procedures a report should be written by filling the specimen submission form. 50