Agonal and PM changes

Question 1

Agonal changes

Answer 1

1) Passive congestion: lungs, liver spleen fill up with blood b/c it’s not going back to the heart- all comes down to reduced venous return
2) pulmonary oedema: increased vasc. pressure d/e impaired venous return
3) pulmonary alveolar emphysema: labored, active breathing (inhalation), passive exhalation moves less air, residual volume remains in alveolar spaces
4) stomach content in oesophagus and trachea- regurg. and aspiration. If reurg or asp occurs wel before death, see inflamm. response. If agonal, no inflamm. response.

Question 2

Euthanasia effects

Answer 2

Direct effects of drug used- crystal formation at serosa and endothelium. Make sure that it’s barbiturate crystals, and not something like calcium mineralization due to chronic disease.

Question 3

PM changes- why they happen

Answer 3

occur after death- cells and tissues disintegrate

Results from: 1) autolysis of cells are CV failures- proteolysis by lysozymal enzmes- self digest

2) bacterial growth- partly due to physiological flor (esp. ruminants)

Question 4

Factors affecting extent of PM change

Answer 4

Tissue of origin: i.e. brain and kidney melt v. quickly

Temperature at death: warm room–> decompose quickly

Fleece/fur thickness: sheep decompose rapidly

Bacterial flor

Death to necropsy interval

Question 5

Algor mortis

Answer 5

cooling

Question 6

Rigor mortis

Answer 6

muscles in contracted state

occurs 1-6 hours after death and disappears after 1-2 days

Question 7

Livor mortis

Answer 7

red- hypostatic congestion

settling of blood

Question 8

Rigor mortis: in depth

Answer 8

Muscle contractions after death- begins after 1-6 hours

Starts in heart (no blood left in heart)- blood pushed from left ventricle

Head and nuck muscles affected less

Extremities last go into rigor- persists for 1-2 days

Muscular animals/atheletes- increased rigor is observed

Excitement/stress pre-death accelerates onset

Extreme malnutrition: rigor may fail to develop due to insufficient energy stores in the muscles (ATP, glycogen) to allow myofiber contraction

Question 9

PM changes: textures

Answer 9

Corneal opacity: reduced turgor

Gas formation: liver and gut (gut d/t bacteria)

Softening: liver, kidney (often embedded in fat), pancreas

PM clots

Drying of tissue surfaces

Question 10

PM bloat/empysema

Answer 10

rumen microbes can produce huge amounts of gas and can stay bloated for up to a weak

Question 11

PM tissue detachment

Answer 11

mucosa of rumen, reticulum, omasum- start to peel off

Hair slip=loss of hair- especialy in fetuses

Question 12

PM color changes

Answer 12

Dark red- hypostatic congestion: blood sinks d/t gravity

Diffuse reddish stain: hemoglobin inhibiton- when RBCs start to break down

Greenish-yellow: bile-staining tissues close to gall-bladder

Green-black: H2S (bowel organisms) and hemoglobin produces sulfmet-Hb.

Hemolytic staining: if killed and bled in abattoir, see a nice clean, white intima. If unbled 12 hours after death, see pink staining of intima. If inblued 1 week after death, very very red intima.

Question 13

PM clots

Answer 13

must distinguish from thrombus

Rubbery and homogenous- form perfect casts of vessels

Mixture of: currant jelly clot (red to blue due to RBCs) and chicken fat clot (clear to yellow d/t serum).

Question 14

Decomposition

Answer 14

decomposition=autolysis and putrefaction

Autolysis= tissue breakdown d/t lack of O2, no inflammatory response. autolysis minimized by chilling (4 degrees C)

Putrefaction: dead tissue invaded by anaerobic saprophytic bacteria. Observe digestion of tissue proteins with gas production. Tissue looks green, black or brown.

NB: putrefaction is generalized

Clostridial myositis can look similar to PM putrefaction but it’s not generalized, it’s localized to affected muscle(s).

Question 15

Important PM artefacts

Answer 15

Freezing: crystallization, cell disruption during thawing

Imperfect bleeding: back bleeding into thorax or inhalation into lungs (mostly pigs). Incorrect angle (i.e. doesn’t serve jug and carotid simultaneously) of knife sluaghter can cause backbleeding into the thorax. If the trachea is nicked, blood can be inhaled into lungs.

Blood splashing: hemorrhages in lung, muscle and other organs. Seen in sheep and pigs slaughtered by electrical stunning. Observe multiple pinpoint hemorhages in lung, muscles, etc.

Emphysema: terminal gasping in old, thin cows especially

Splenomegaly: due to anaesthesia/barbiturate euthanasia

Barbiturate crystalization