topic 7: necropsy Flashcards
what is necropsy
-is the thorough examination of an animal’s body after death to determine the cause of death or to study disease processes.
- It involves a systematic and detailed analysis of the animal’s tissues, organs, and bodily fluids to identify abnormalities, injuries, or diseases.
purpose of necropsy
1 Diagnosis: Determining the specific cause of death or
disease.
2.Research: Studying disease mechanisms or new
treatments.
3.Public Health: Identifying zoonotic diseases (those that can be transmitted from animals to humans).
4.Legal and Insurance Cases: Establishing cause of death in cases involving legal claims, such as insurance or animal welfare cases
what are the processes/steps invloves in necropsy
I. Pre-necropsy
* II. Preparing for a necropsy
* III. Transporting specimens
* IV. Necropsy Procedure
* V. Post necropsy
pre necropsy
1.Animals in groups; fishes, poultry, goats, dogs & cats in shelters, experimental animals
* History
* Examine live animals, and collect specimens based on
suspected diseases
* Select animals in various stages of disease for post
mortem
- Individual animals; pets
* History
* Examine animal (if still alive) , and collect specimens
based on suspected diseases
* Do not have a preconceived diagnosis, and keep in mind work procedures to prevent transmission of contagious
diseases
II. Preparing for a necropsy
1.Prepare suitable PPE – lab coats, coveralls, gloves,
goggles, mask
2. Pre-label specimen containers – using permanent ink or pencil
3.Prepare required instruments eg. Scissors, scalpel
blades, forceps, bone cutters
4.Prepare sufficient fixative – 10% buffered formalin
III. Transporting specimens
Swabs and tissues collected for microbiological testing
should be collected aseptically,(use sterile instruments)
placed in transport medium or sterile containers.
* Transported to the lab asap or refrigerated (packed in ice) during transport
IV. Necropsy Procedure
1.Always perform an external examination of the dead
animal.
2.Follow the protocol for necropsy for that species.eg. Place ruminants on their left side and horses on their right side.
3.Note the relative positions of organs within body cavities
4.Aseptically collect any abnormal body fluid found in body cavities or organs
5.Aseptically collect any abnormal lesions together with
adjacent normal tissue for histological examination – 10% buffered formalin
* Examine and collect specimens from organs in thoracic cavity before organs in abdominal cavity
V. Post necropsy
1.Dispose of carcass and organs in biohazard bags
2.Clean and disinfect all work surfaces
3. Wash and disinfect all equipment
4. Record the necropsy findings
what are lesions
refer to abnormal changes in the structure or
function of tissues or organs, often caused by disease, injury, or infection.
why do we need to know the different characteristics of lesions
The characteristics of lesions can vary greatly depending on their cause, location, and severity.
* Understanding these characteristics is essential for
diagnosis and treatment in both human and veterinary medicine.
what are the 10 characteristics of lesions
- size
- shape
3.colour
4.consistency/texture
5.location - distribution
- borders/margins
- surface features
- contents
- odour
what are the different sizes of lesions and thier importance
- can be micrscopic (only visibile under a microscope)
-can be large mases, easily visible to the naked eye
importance: measuring lesions size help in assessing its potential impact on the body
what are the different shapes of lesions and what could they indication , purpose of finding this info out
shape: round, oval, irregular, linear
importnace: give us clues on the cuase
circular:can indicate parasitic infection
irrecgular: might indicate trauma or cancer
what do the different colour of lesion indicate and the importance of knowing this info
purpose: indicate underlying processes
red: inflmmation, hemmorage, hyperemia (increase blood flow)
pale/while: reduced blood supply, fibrosis, necrosis (tissue death)
yellow: often associated with pus or fat accumulation
green: bacterial infection or gangrene (death of tissue because of ischemia)
black: indicates tissue necrosis or presence of melanin
what are the different Consistency/Texture of lesions
soft: often associtaed with inflammation, edema, certain tumors
firm: could indicate fibrosis or solid tumors
fluid-filled: suggests cysts (gas.fluid,solid slowly growing), absess (pus) or vesicles (small amt of fluid like blister, easily rupture)
gritty/heard: might indicate calcifucation or mineral deposits
what are different locations of lesions, importance of knowing this and example
-appear on skin
-or appear inside body, affecting organs or tissues
eg,skin lesion suggest dermatitis
lung lesion indicate pneumonia or tumors
purpose of knowing this: the specific location can narrow dow potential causes
what are the different types of distribution of lesions
focal: a single, issolated lesion in one area
mutifocal: mutiple lesions scattered throughout an organ or tissue
diffuse: lesion involves a large, continuous area of tissue (whole organ)
segmental: lesions affecting specific sections of an organ (section of an organ)
what are the different types of borders/margins
well-definied: lesions with clear,distinct edges, often seen in bening conditions or trauma
poorly defined: lesions with blurry, indistict margins, often indication agressive process such as malignant tumors or infections (spreading so edges are not clear)
what are the different surface features of lesions and what can they indicate
purpose: help us determine the progression and severity of the lesion
raised- indicate growth or selling-often seen in tumore/nodules
flat- may suggest changes in tissue without significant growth (not much change to tissue yet)
depressed: often associated with tissue loss or necorsis
ulcerated (open wound): occurs when the surface tissue breaks down, creating an open wound
what are the differernt contents of lesiosn and imp of knowing this info
imp of knwing this: its nature can provide important diagnostic info
serous: clear, water fluid- indicative of mild inflmation
purulent: pus filled- often seen in bacterial infections
hemmorrhagic: blood filled- may occur in classes of trauma or certain cancers
what does odor from lesions suggest
Some lesions may emit a distinct odor, especially those
associated with infection, necrosis, or gangrene. Foul
smelling lesions may suggest bacterial infection or tissue decay
what are the steps for ontaining and preserving speciments for histology
- selection of tissue sample: indetifying area of interest, tissue size
- fixation of tissue
- labelling and documentation
how is tissue selected for 1. selection of tissue sample
- identifying area of interest: tissue sampel must be taken from appropriate are to answer specific diagnostic/ research questions
-abnormal areas: lesions, tumors, inflammed tissues
and
- normal surrounding tissue for comparison - tissue size: should be no more than 1cm in thickness-> too aloow for adawuate penertration fo the fixatives and ensure proper processing
thicker sample-> hinder fixation-> lead to poor quality sections
what is the purpose of fixation of solution
-to preserve the tissue’s structure and prevent degradation or autolysis (self-digestion by enzymes)
-it also helps to maintain the intergrity of cellular components like proteins, nucleic acids and lipids for staining and analysis
what are common fixatives used for fixation of tissue
- fromalin: most commin (10% neutral-buffered formaline)
its effect: corss-links prtien to stebalise tissue structure - glutaraldehyde: used for electron microscopy-> providing more detailed preservation of ultrastructure
what is the fixation time
tissue should remian in the fixative for specific duration (12-24 hrs) depending on teh tissue type and thickness
inadaquate fixation can lead to artifacts
over fixation-> make tissue too rigic for sectioning
for labelling and documentation, what are the necessary informaition needed to be writeen on the tissue container
labelling: identifying information such as patient’s name, speciment type, date, any other relevant data.
mislabellign can result in significant errors in diagnosis
documentation: reason for biopsy, clinical histiry, sepcific site of sample collection (complete clinical info)
