SYSTEMIC PATHOLOGY OF DIGESTIVE SYSTEM OF FISH

Md.Atick Chowdhury

Systemic Pathology of TeleostThe Integumentary SystemThe Respiratory SystemThe Digestive SystemThe excretory System

The Digestive SystemDigestion is the process of converting food

into smaller compounds that can be used by the body.

Mouth Buccal Cavity Phyrynx Oesophagus Stomach Pyloric caeca Intestine The Pancreas Liver Rectum Anus

The Digestive System

Figure: Teleost Digestive System

Oral Cavity The oral cavity of the teleost is a hard, bony

structure, which is well adopted to prehension of rough materials.

Common Diseases:Lesions:

Caused by fishing hook & developed into infected ulcers.

Necrotic fungal infection: Occur in upper jaw.

Neoplasia: Lesion of the lips or of pharynx. Caused by polluted water.

Oral Cavity

Figure: Normal Structure of Oral Cavity

Figure: Pathology of Oral Cavity

OesophagusOeosophage is situated after pharynx, a

muscular tube that leads to the stomach.Common Diseases:

Degenerative myopathy:o Develop in muscle of oesophagus.o Occurs due to vitamin E.

Figure: Normal Structure of Oesophagus

Figure: Pathology of Oesophagus

Swim Bladder A gas-filled structure in many fishes that

functions to maintain buoyancy & helps in respiration.

Common Diseases: Oedema:

Caused by chronic bacterial infection. Inflammation:

Due to raise of temperature. Distension:

Assosiated with pathological lesions. Due to feeding on dusty food.

Swim Bladder

Figure: Normal Structure of Swim Bladder

Figure: Pathology of Swim Bladder (1: Inflammation, 2: Distention, 3: Oedema)

1

2 3

The StomachAfter oesophagus true stomach is found.Common diseases:

Bacterial lesions: Occurs occasionally within the muscular is of the

stomach and external serous.Ascites:

Increased fluid found in stomach cavity.

The Stomach

Figure: Normal Structure of Stomach

Figure: Pathology of Stomach

The IntestineThe intestine is a long thin tube with a thin

double layer musculature.Common diseases:

IPN (Infectious Pancreatic Necrosis): Infectious Pancreatic Necrosis Virus Does not take food Fish show abnormal distension

IHN (Infectious Haematopoietic Necrosis): Infectious Hematopoietic Necrosis Virus (IHNV)

CCVD (Channel Catfish Viral Disease): Channel Catfish Virus (CCV) Abnormal movement Swelling

The IntestineVHS (Viral Hemorrhage Septicemia):

VHSV (Viral Hemorrhage Septicemia Virus) Dark color on intestine skin Swollen structure

Chronic infection: Caused by fungus such as Mycrobacterium or

Nacardia asteroides. Focal granullomatous infecton of the gut wall

The Intestine

Figure: Normal Structure of Intestine

Figure: Pathology of Intestine

Liver It has no specific shape and has 2 or 3 tissues. Common diseases:

Hepatic Necrosis: Diphyllobothrium sp., Aeromonas salmonicida Nausea, weakness, abdominal pain.

Lipid infiltration: Fatty infiltration of liver cell is common in farmed

fishes. Liver enlarges Yellow or light brown color Loses its sharp edge of its lobes.

Hepatic granuloma: Caused by a wide range of pathogen. Renibacterium salmoninarum, Mycobacterium

fortuitum.

Liver Euclinostomum:

Caused by Digenean parasites. Blood vessel degeneration:

Blood vessel degenerates rapidly. Vaccume:

Cell reduced causing vaccume condition. Bacterial colony:

Several bacteria attacks & forms colony.

Liver Pigment accumulation:

Most common is accumulation of ceroid and lipofuscin

These byproduct catabolism are seen in liver cells & hemopoietic tissue.

The biliary system: It includes gallbladder, bile ducts and certain cells

inside the liver & bile duct outside the liver. Protozoan parasites are frequently observed in the

gallbladder. Pathological changes resulting from biliary disease

depend on the level of the lesion.

Liver

Figure: Normal Structure of Liver

Figure: Pathology of Liver

Figure: Digenean sp.

PancreasPathology of the teleost pancreas is complex.

Pancreatic tissue located in externa around the portal vein system within the liver.

Common diseases:IPN (Infectious Pancreatic Necrosis):

Infectious Pancreatic Necrosis Virus Responsible for acute & chronic exocrine

pancreatitis. Affected fish have massive necrosis of the pancreas

and mortalities can be 20-30%CCVD (Channel Catfish Viral Disease):

Channel Catfish Virus (CCV)IHN (Infectious Haematopoietic Necrosis):

Infectious Haemopoietic Necrosis Virus

Pancreas

Figure: Normal Structure of Pacreas

Figure: Pathology of Pancreas

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