Transcript File

GENERAL PATHOLOGY
AHT 04107
BY A.NEWTON.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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Classification of haemorrhages:
a)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.
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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.
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.
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.

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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.
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
v) EMBOLISM; Presence and floating of
foreign bodies(emboli)in the blood
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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
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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
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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.

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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

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
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)
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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.

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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.
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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.
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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.
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 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.
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-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
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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.
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-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.

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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.
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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.
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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.
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According to tissue affected.
Pancrease-pancreatitis.
Veins-phlebitis
Ear-otitis
Bone-osteotitis
Joint-arthritis
Muscle-myositis
Penis-balanitis
vagina-vaginitis.

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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.

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- 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.

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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…

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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 liver
cells, 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.
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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 collagen
that imparts mechanical strength to the
growing tissue.
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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.
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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
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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.
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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.

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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

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(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.
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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 larynxpharynx region, open trachea.

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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.
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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.
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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.
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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.
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PROCEDURE FOR TAKING
PATHOLOGICAL SPECIMEN.
IDENTIFY
1. Clinical signs of the patient.
2. Compare these with the details on the
Request Form(s) – they must all match.
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COLLECT
3. Collect all the specimens and place them
into their appropriate unlabelled tubes.
4. Remove collection devices and make the
patient comfortable.
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LABEL
5. Label the specimen(s) with
 -UR Number
 -Surname
 -Given Name
 -Date of birth
 -Date and Time of Collection
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6. Print ‘your name’ in the Collected By box on
the Request Form.
7. Complete the Date and Time of Collection
box on the Request Form.
8. Place the Request Form into the open
compartment of the Biohazard Bag.
9. Place the specimens into the sealable
compartment of the Biohazard bag.
Some specimens need to be transported on ice
or in a hot box or in a thermos – those
Specimens should be placed into those
containers instead.
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DISPATCH
10. Arrange for the transport of the
specimens to the Laboratories as soon as
possible.
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“THE END’’
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