PM examination

Question 1

What is gross pathology?

Answer 1

• recognition and description of macroscopic, morphological changes to tissues and organs, in the live or dead animal at biopsy, surgical removal, PM
  
  • definitive diagnosis
  • potential problems correlating with clinical signs
  • pathogenesis/ mechanisms
  • not enough

Question 2

Why do a PM?

Answer 2

• diagnosis
• surveillance
• population/ herd health
• zoonosis
• sudden death
• owner wants to know
• obtaining samples
• research
• insurance
• forensic
• why treatment didnt work

Question 3

External exam in PM?

Answer 3

• rigor mortis?
• condition
  
  • subcutaneous adipose tissue
  • adipose tissue - around organs, behind eyes, marrow cavities
  • no BCS
  • give descriptor
• wounds/ lesions
• coat condition - ectoparasites
• discharge from orifices
• colour of skin, sclera, mucous membranes
  
  • pale gums = anemia

Question 4

How to examine the skin and subcutanous tissue?

Answer 4

• disarticulate the limbs - stable
• incision along midline from the madibular symphysis to pubis
• reflect skin away - see muscle and sub. tissue
• check for bruising/ fat
  
  • yellow - icterus
  • pallor - blood loss/ anemia
  • red - congestion/ sepsis/ bruising
  • green - bile imbibition/ pseudomelanosis
  • gelatinous - serous atrophy of fat/ oedema

Question 5

How to examine abdomen/ abdominal cavity?

Answer 5

• cut along linea alba
• collect any fluid in the abdominal cavity
• cut along last rib on each side to open cavity
• check for fluid
• check of -ve pressure in thoracic cavity - make small incision into diaphragm - air goes in/ lungs inflate
  *

Question 6

Reasons why there would be air in chest?

Answer 6

• surgery
• penetrating wound
• tumour
• damage to oesophagus/ trachea
• organs in thoracic cavity
• diaphragm rupture - hernia
• bacteria producing gas
• pus

Question 7

How to examine the thoracic cavity?

Answer 7

• cut along costochondral junctions on 1 side
• reflect ribcage (cut through mediastinum)
• slide the knife along the costochondral junctions to expose contents

Question 8

How do you remove the pluck?

Answer 8

• pluck = tongue, larynx, thyroids, parathyroids, oesophagus, heart, lungs
• cut medially down the mandible - ramus to symphysis
• during the incision reflect tongue ventrally
• hold the tongue and move ventrally and caudally
• examine the hyoid apparatus before cutting through cartilaginous joints
• continue reflecting the tongue, larynx, oesphagus, trachea caudally and ventrally (by cutting the fascia dorsal)
• remove the heart and lungs still attached
• cut the aorta, vena cava and oesophagus at the level of the diaphragm

Question 9

How do you check the patency of bile duct?

Answer 9

• make a small incision in duodenum
• squeeze gall bladder
• bile should ooze from incision

Question 10

What is done after pluck removal?

Answer 10

• bile duct checked
• adrenal glands removed
• liver/ spleen removed
• GIT removed
• Urinary tract removed
• ovaries/ uterus/ testes removed
• check lymph nodes
• check joints
• remove thyroid/ parathyroids
• open oesophagus
• open trachea, larynx, bronchi
• open heart
  
  • examine all chambers and valves
  • L ventricular free wall, interventricular septum, R ventricular free wall - 3:3:1
  • dog - <1%
  • cat - < 18-20g
  • examine myocardium, endocardium, epicardium
• remove capsule of kidneys
• bisect kidneys - medulla, cortex, pelvis, urethra
• collect urine
• open bladder/ urethra
• open GIT
• collect/ describe stomach/ intestinal contents
• remove head
  
  • check foramen magnum - is cerebellum pushing through
  • open cranial vault
  • check meninges
  • remove eyes/ brain
  • (fixed whole for 1 week)

Question 11

What are the PM changes?

Answer 11

• algor mortis
  
  • cooling after death
  • faster in smaller animals
  • slower in animals with hair, excess adipose, herbivores
• rigor mortis
  
  • contraction of muscles
  • due to lack of ATP to break down cross links
  • appears absent in emaciated animals (not enough muscle) and in frozen animals
• decompisition
  
  • autolysis - self digestion
    
    • gall bladder
    • brain
    • pancreas
  • putrefaction
• desiccation
  
  • loss of water in tissues exposed to air
  • eyes and mucous membranes
• insect colonisation
• livor mortis = lividity = hypostasis = hypostatic congection
  
  • pooling of blood depends on gravity
  • will form a pattern that will stay even if moved
• clotting vs thrombi
  
  • clotting - PM change - wont be attached to vessels/ form casts
    
    • paler - chicken fat
    • darker - redcurrent jelly
  • thrombi - alive - attached - go in direction of blood flow
• imbibition
  
  • haemoglobin- staining red due to erythrocytes rupture
  • bile - green
  • pseudomelanosis - blue/green/black - hydrogen sulfide produced by bacteria

Question 12

How do you describe a lesion?

Answer 12

• organ
• position
• number
• weight
  
  • as a %
• distribution
  
  • random
  • symmetrical
  • focal
  • multifocal
  • muultifocal to calescing
  • miliary
  • segmental
  • diffuse
• contour
  
  • raised
  • depressed
  • flat
• size
• colour
• shape
• consistency
• smell
• sound