Viral Diseases

Chicken Infectious Anemia (Blue Wing)

Replicates in bone marrow and cortex of the thymus

Thymic atrophy and bone marrow change from pink to fatty

Immunosuppressive leading to secondary bacterial infections

Infectious Bursal Disease (Gumboro)

Immunosuppressive disease caused by serotype 1

Causes whitish/watery diarrhea and vent picking is seen

Bursal atrophy, edema and hemorrhaging seen in gizzard, proventriculus, thigh and breast muscles

Marek’s Disease

Neoplastic disease leading to lymphoid tumors on visceral organs 

Nerve trunks are infiltrated (sciatic and vagus) leading to neurologic signs 

Immunosuppressive via B cell lysis 

Lymphoid cell infiltration also occurs in iris

Birds become lifetime carriers and shed virus in feather dander 

Lymphoid leukosis 

Serotype J causes neoplasia of the bursa that can metastisize to the liver 

Viral Arthritis

Lameness, lack of uniformity and discoloration and swelling seen at the hock joint.

Green legs seen at processing plant 

Transmitted vertically

Low Pathogenic Avian Influenza

Mainly respiratory signs seen

Inflammation of the airways

High Pathogenic Avian Influenza

Sudden high mortalities

Nervous symptoms like torticollis

Hemorrhages/cyanosis in comb and wattles 

PM hemorrhages seen in trachea and proventriculus 

Newcastle Disease

Can have acute respiratory and neurological signs

In severe cases enteric conditions, neurological signs, misshapen eggs, swollen heads

On PM hemorrhage is seen in conjunctiva, proventriculus, cecal tonsils, intestine

Infectious bronchitis

S1 infects URT and reproductive tract

Can have high mortality 

Respiratory signs, drop in egg production with misshapen eggs and watery albumen likely caused by a cystic oviduct 

PM: mottled kidneys, cystic left oviduct 

Curled embryo on virus isolation

Infectious Laryngotracheitis

Lifelong carriers due to dormancy in trigeminal ganglion

Respiratory signs with hemorrhagic tracheitis, a yellow caseous plug and almond shaped eye 

On histology multinucleated syncytial cells with intranuclear inclusion bodies seen

Causes pocks on CAM

Pox Virus

Can present as nodular lesions and scabs on non-feathered areas or as yellowish nodules in mucus membranes of mouth, oesophagus, trachea

Results in mild-severe respiratory signs 

Transmitted by mosquitos and cannibalism 

Histology: Bollinger bodies and ballooning 

Avian encephalomyelitis

Biphasic transmission and possible vaccine induction

Neurological signs and lameness seen in birds

PM: pale foci in gizzard and lens opacity

Histology: increase in glial cells and perivascular cuffing 

Inclusion Body Hepatitis

Sudden mortalities in young broilers

Labored breathing, paleness, distended abdomen and neurological signs

On PM: liver swollen, friable, yellow-tan with hemorrhaging; kidneys swollen and mottled; hemorrhaging on muscles 

Histology: Intranuclear inclusion bodies in liver 

Egg Drop Syndrome (Duck adenovirus 1)

Eggs have lack of pigment and chalky appearance but birds appear healthy

Hemagglutination see on serology 

Hemorrhagic Enteritis

Frank blood seen in droppings and blood on skin and feathers around vent region.

PM: Distention of small intestine with blood-mixed contents; enlarged spleen with marbled or mottled appearance 

Quail Bronchitis 

Respiratory signs and intranuclear inclusions seen in trachea and lungs of quail 

Avian Metapneumovirus

Chickens seen with swollen heads

PM: sinusitis and swelling of infraorbital sinuses with casseous material seen