Pathology of Respiratory System

10 Questions

What is a common sign of sinusitis in turkeys 4 weeks of age or younger?

Wet, tenacious, brownish exudates on the head and wings

What is a characteristic of nasal and tracheal exudates in the later stages of disease?

Tenacious and mucoid

Which of the following is NOT a typical sign of turkey coryza?

Swollen infraorbital sinuses

What is a common complication of Bordetella avium infection in young turkeys?

Airsacculitis

When can tracheal softening be palpated through the skin of the neck?

During the second week of disease

What is the typical morbidity rate in turkeys 2-6 weeks of age infected with Bordetella avium?

80-100%

What is a risk factor for high mortality rates in young turkeys infected with Bordetella avium?

All of the above

What is a characteristic of gross lesions in turkeys infected with Bordetella avium?

Confined to the upper respiratory tract

What is a common sign of Bordetella avium infection in older turkeys?

Dry cough

How long do signs of the disease typically take to subside?

2-4 weeks

Study Notes

Gross Lesions

Nasal and tracheal mucosa edema and hyperemia apparent during the first 2 weeks of infection
Inflammation of turbinate and sinus, as well as submaxillary swelling
Tracheal rings soften and distort in proximal segments, leading to tracheal narrowing and larynx retraction

Microscopic Lesions

Cilia-associated bacterial colonies, cilioectasis, and deciliation (progressive loss of ciliated epithelium) are distinctive characteristics of Bordetellosis
Bacteria adhere specifically to cilia and have not been found attached to other cell types
Colonized cells have increased eosinophilia of the apical cytoplasm and may protrude slightly from the mucosa

Tracheal Mucosa

Bacterial colonies are most apparent on the tracheal mucosa 1-2 weeks after onset of clinical signs, before loss of ciliated cells is extensive
In the uncomplicated disease, the tracheal epithelium can return to normal 4-6 weeks after the onset of clinical signs

Diagnosis

Based on case history, clinical signs, and post-mortem lesions
Isolation and identification of the causative agent (Bordetella avium) through sampling and culturing of the trachea

Clinical Signs

Sinusitis and upper respiratory signs are more common in turkeys 4 weeks of age or younger
In older turkeys, the most typical sign is dry cough
Some birds develop submandibular edema (balloon-like) and almond-shaped eyes
During the first 2 weeks of disease, the nares and feathers of the head and wing become crusted with wet, tenacious, brownish exudates
Tracheal softening can be palpated through the skin of the neck in some birds beginning in the second week of disease

Morbidity and Mortality Rates

High morbidity (80-100%) and low mortality (<10%) in turkeys 2-6 weeks of age
Infection of a breeder flock with B. avium resulted in only 20% morbidity with no mortality
High mortality rates (>40%) in young turkeys are associated with concurrent isolation of Escherichia coli or other concurrent respiratory pathogens