This document describes the gross lesions and pathological signs of various avian diseases. For Pullorum Disease, lesions include an enlarged bronze greenish liver and splenomegaly. For colibacillosis, airsaculitis presents as thickened cheesy exudates in the air sac. For infectious bursal disease, the bursa is enlarged, edematous, and hemorrhagic with gelatinous exudates. For Marek's Disease, tumors can form in various organs and present as distinct whitish skin nodules.

1. Avian Pathology

2. •Liver: Enlearged, congested and
presence of haemorrhagic streaks
•Heart: Necrotic foci or nodules in
cardiac muscles and pericarditis
•Yolk: Unabsorbed, yolk sac content
may be cheesy, yellow or dark red.
Pullorum Disease

3. Fowl typhoid
• Enlarged and bronze greenish
tint of liver, sometime
mottled with multiple
milliary necroses
• Splenomegaly (2-3 times
bigger) sometimes with
grayish-whitish nodules on
the surface
• Enteritis in anterior part of
small intestine with
ulcerations

4. Colibacillosis (Gross lesions)
 Airsaculitis: (5-6 weeks of age)
• Thickened and caeseous exudates in
the air sac
• Adherence pericarditis
• Fibrinous perihepatitis
 Omphalitis (Yolk sac infection)/ Naval
infection: (early age)
•Reddish and oedematous tissue in the
umbilical region
•Abnormal and unabsorbed yolk sac
•Peritonitis
•Bloated and macerated abdominal
cavity

5. Colibacillosis (Gross lesions)
 Coliseptisemia: (Young to mature
birds)
• Green colored liver with small
necrotic foci
• Swollen parenchymatous organs
• Pericarditis
• Peritonitis
 Coligranuloma:
• Nodules occur along the intestinal
tract, mesentery, liver
• Resembles to TB

6. Fowl cholera
• Petechial haemorrhages in heart, anterior part of
the small intestine, the gizzard or the abdominal
fat
• Small whitish necrotic in liver
• Serofibrinous exudation with congestion in lung

7. Infectious Coryza
• Sub-coetaneous edema in face & wattles
• Congestion of nasal mucosa and
exudates in infra orbital sinuses.
• Catarrhal exudates in trachea

8. Aspergillosis
• Yellowish, homogenous consistency
nodules with varying size from pin
headed to 4mm in diameter found mainly
in lungs.
• Thickening of air sacs.
• Growth of fungi in air sacs and lungs.

9. Chronic Respiratory Disease (CRD)
• The chicks die at piping stage and found
cheesy materials in air sac.
• Haemorrhage & congestion in tracheal
mucosa and contain creamy-yellowish mucus.
• Air sac become cloudy and containing cheesy
materials.

10. Ranikhet
 Hemorrhage in the proventriculus specially
on the tip of the papillae
 Caecal tonsils and pyear patches are
hemorrhagic & distended
 Petechial heamorrhage in serosal surface of
visceral organ
 Catarrhal exudates found in trachea
 Button shape ulcer the intestine
 Congestion of the lungs and brain

11. Infectious Bursal Disease
 Enlargement, edematous, inflammed and
heamorrhaic bursa
 Gelatinous exudates around the bursa,
heamorrhage in bursa giving blackish brown
colour
 Patechial heamorrhage at the junction of
proventriculus-esophagus and proventriculus-
gizzard
 Pin point heamorrahage on thigh muscle and
breast muscles

12. Avian influenza
 Oedematous face including comb and wattle
which are cyanotic in colour.
 Reddish colour carcass due to sub-cutaneous
congestion.
 Haemorrhage on epicardium, breast muscles,
inner surface of sternum and other
musculature.

13. Infectious bronchitis
• Serous, catarrhal or caseous exudates in
respiratory tract
• Air sacs contain foamy exudate initially,
progressing to cloudy thickening
• Cystic dilation of oviduct and ova may
rupture
• Enlarged kidney with deposits of urates
and ureter become distended

14. Marek’s Disease
• Thickening of nerves (Sciatic,
Brachial, Vagus ) with loss of cross
striations
• Tumor of malignant lymphoma in
ovary/testes, liver, lungs, spleen,
muscles, heart, kidney,
proventiculus and intestine
• Tumor on skin (Distinct whitish
nodules, scab like, brownish crust
formation)

15. Coccidiosis
 Haemorhagic enteritis and thickened
intestinal wall.
 Coagulated blood mixed with dropping
formation of core in caeca (caecal core)
 Bloody exudate in lumen of small
intestine.

16. Aflatoxicosis
• Enlarge, friable, yellowish & fatty liver,
thicken bile duct.
• Hemorrhage in intestine.
• Atrophy of spleen & bursa.
• Hemorrhage in muscles, loose
attachment of gizzard muscle.