Quaglio - Necropsy techniques

Question 1

What is the purpose of performing a fish necropsy?

Answer 1

To identify the cause of death or disease.
To observe gross lesions and collect samples for laboratory analysis.

Question 2

What are the preparatory steps for a fish necropsy?

Answer 2

Euthanize the fish humanely (e.g., using MS-222).
Place the fish on a clean, flat necropsy surface.
Ensure the necessary tools (scalpel, scissors, forceps) are sterile.

Question 3

What are the key steps for external examination during necropsy?

Answer 3

Inspect for abnormalities in body shape (kyphosis, lordosis, scoliosis).
Observe skin for ulcers, hemorrhages, lesions, and mucus.
Check fins and scales for damage.

Question 4

What tools are commonly used during fish necropsy?

Answer 4

• Scalpel
• Scissors
• Forceps
• Dissecting needles
• Formalin for tissue preservation

Question 5

What are the key observations during external inspection?

Answer 5

• Skin color changes (melanosis, pallor)
• Lesions or nodules
• Deformities (spinal abnormalities)
• Condition of fins and opercula

Question 6

How is the fish abdomen opened during necropsy?

Answer 6

Make an incision from the anus to the opercula.
Cut along the ventral midline below the lateral line.
Remove the abdominal wall to expose internal organs.

Question 7

What organs should be examined during necropsy?

Answer 7

• Heart
• Liver
• Spleen
• Kidneys
• Swim bladder
• Gastrointestinal tract

Question 8

What abnormalities are checked for in the liver during necropsy?

Answer 8

• Color changes (yellow for steatosis, pale for necrosis)
• Presence of petechiae
• Focal necrosis or granulomas

Question 9

How is the heart examined during necropsy?

Answer 9

Inspect for nodules or granulomas on the epicardium.
Check for hemorrhages or necrotic areas.
Note any signs of systemic infection.

Question 10

What is the significance of spleen examination during necropsy?

Answer 10

Enlarged spleen (splenomegaly) may indicate systemic infection.
Granulomas or nodules can suggest bacterial or parasitic infections.

Question 11

What changes in the kidneys are observed during necropsy?

Answer 11

• Swelling or friability
• Granulomas (e.g., in mycobacteriosis)
• Signs of Proliferative Kidney Disease (PKD)

Question 12

What signs of disease are observed in the swim bladder?

Answer 12

• Hemorrhages or thickened walls (e.g., Anguillicola crassus infection)
• Presence of parasites or gas emboli

Question 13

What is the purpose of examining the gastrointestinal tract during necropsy?

Answer 13

• To identify enteritis or internal hemorrhages.
• To check for parasitic infestations or nodules.
• To observe abnormalities in digestive content.

Question 14

What role does the operculum play in necropsy?

Answer 14

Removed for gill examination.
Observes gill color, lesions, and parasites.

Question 15

Why is gill examination important in necropsy?

Answer 15

• Gill pallor may indicate anemia.
• Nodular gill disease (NGD) caused by amoebae or parasites.
• Hyperplasia or necrosis linked to water quality issues.

Question 16

How are tissue samples preserved for histopathology?

Answer 16

Place samples in 10% neutral buffered formalin.
Avoid freezing samples to prevent tissue damage.

Question 17

What should be avoided when transporting fish for necropsy?

Answer 17

• Do not send decomposed fish.
• Avoid placing paperwork in bags with fish samples.
• Use ice packs for fresh fish transport.

Question 18

How can spinal deformities be detected during necropsy?

Answer 18

Observe externally for kyphosis, scoliosis, lordosis.
Radiography or X-rays can confirm skeletal issues.

Question 19

What causes spinal deformities in fish?

Answer 19

• Vitamin deficiencies (e.g., Vitamin C)
• Trauma or electrical induction
• Genetic abnormalities

Question 20

What is the role of histopathology in necropsy?

Answer 20

• Identifies cellular-level abnormalities.
• Detects infections like mycobacteriosis.
• Confirms parasitic infestations.

Question 21

What are signs of granulomas in internal organs?

Answer 21

• Hard nodules in organs like liver, spleen, kidney.
• Indicate chronic infections (e.g., tuberculosis, nocardiosis).

Question 22

What is the sequence of incisions for fish dissection?

Answer 22

• Make a ventral incision from the anus to the head.
• Extend cuts laterally to expose the abdominal cavity.
• Carefully remove the muscle to view internal organs.

Question 23

Why is it important to examine skeletal muscles during necropsy?

Answer 23

• Detects hemorrhages, necrosis, or cysts.
• Identifies parasites like Triaenophorus crassus or Diphyllobothrium larvae.

Question 24

What are petechiae, and why are they significant?

Answer 24

Small, pinpoint hemorrhages observed in organs.
Indicate systemic infections or septicemia.

Question 25

How is the gall bladder assessed during necropsy?

Answer 25

• Check for bile discoloration.
• Observe for parasites or signs of hepatobiliary disease.

Question 26

What abnormalities in the eyes can be detected during necropsy?

Answer 26

• Exophthalmos (protruding eyes) in gas bubble disease.
• Cloudiness or ulcers due to bacterial or fungal infections.
• Cataracts caused by Diplostomum.

Question 27

What is the importance of maintaining sterility during necropsy?

Answer 27

Prevents contamination of samples.
Ensures accurate laboratory results.

Question 28

How are necropsy findings documented?

Answer 28

• Record detailed descriptions of lesions.
• Photograph abnormalities for future reference.
• Label samples with species, date, and location.

Question 29

Why is early necropsy crucial after fish death?

Answer 29

Autolysis begins 15–30 minutes post-mortem.
Delayed necropsy reduces diagnostic accuracy.

Question 30

What observations can be made in fish with myxosporid infections?

Answer 30

• Cartilage deformities (e.g., caused by Myxobolus cerebralis).
• Presence of cysts or spores in tissues.
• Associated skeletal abnormalities.