Differential Diagnoses for Chicken Respiratory Diseases

K Ganapathy DVM PhD DipECPVS MRCVSLecturer in infectious diseases (poultry)

RCVS Recognized Specialist in Poultry MedicineDiplomate, European College of Poultry Veterinary Science

Email:gana@liv.ac.uk

A MEMBER OF THE RUSSELL GROUP

& School of Veterinary Science

Content: Chicken respiratory diseases• Anatomy & physiology

• Factors leading to respiratory diseases

• Clinical signs and lesions

• Differential diagnoses• Laboratory support• Control & Prevention• Conclusions

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Broiler

Farm - arrival

Layer Breeder

Brooding

Growers

Respiratory system

• Upper respiratory tract• Nares

• Mechanical filters• Nasal cavity

• conchae• Paranasal sinus

• Infraorbital sinuses

micro-filteration, warms moisture

• Lower respiratory tract• Air passes through the Choanae to larynx.• Larynx – not connected to sound creation.• Larynx to trachea (complete cartilaginous rings)• End of trachea, bifurcates onto bronchus

]

Respiratory system• Syrinx

• Trachea bifurcation form the syrinx – movable structure responsible for sound cremation

• Syrinx compose:-• Caudal tracheal rings• First cartilaginous left bronchus• First cartilaginous right bronchus• Middle cartilaginous ‘partition wall’

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Dr. A. Herrmann

A Herrmann

Respiratory system• Bronchi, air sacs and lungs

• No diaphragm in birds• Lungs are fixed, do not expand• Behind the syrinx, left and right primary bronchi

branches out from trachea• Primary bronchi crosses lungs, forms parabronchi and

tertiary bronchi, and all interconnected• Then empty into the air sacs• Air sacs – plays essential role

• Number of air sacs variable depending on species• See diagram for the locations of air sacs• Thoracic and abdominal muscle movements allows

inspiration and expiration of air and movements

Chicken respiratory disease – summary

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Chickens

Host Environment

AGENT

Interplay between AGENT, hosts and environment

Host Environment

AGENT

disease process

Outcome

others reproductiveneurology

skin m/skeletal GUTrespiratory

Immunosuppresed flock

Environment

AGENT

disease process

Severe-Outcome

others reproductiveneurology

skin m/skeletal GUTrespiratory

Chicken respiratory diseases

• InfectiousViruses BacteriaChlamydiaMycoplasmasProtozoaFungi/yeastsInternal parasitesExternal parasites

• Non-infectiousTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

Chicken respiratory diseases

• Non-infectiousTumoursBehaviour

NutritionManagementEnvironmentPhysicalChemical

Vitamin A deficiency

Respiratory signs – ocular and nasal discharges,IOS swelling, cheesy exudate in eyes.

Lesions – exudate in the IOS, mostly cheesy - swelling of oesophageal glands

Other impact – integrity of respiratory epithelium affected.

Chicken respiratory diseases

• Non-infectiousTumoursBehaviourNutritionManagementEnvironmentPhysical

Chemical

Excessive use of formalinhatcheries

Respiratory signs – increased mortality week 1, sneezing, coughing, ocular-

nasal discharge, gasping?Lesions – those associated with CCRD including tracheal plugsOther impact – disease and losses due to hatchery vaccination due to respiratory injuries

Chicken respiratory diseases

• Non-infectiousTumoursBehaviourNutritionManagementEnvironmentPhysical

Chemical

Feed – mycotoxins- BF, thymus and others

- reduce feed intake

Adverse effects on respiratory tracthealth due to immunosuppressionand loss of micronutrients.

Chicken respiratory diseases

• Non-infectiousTumoursBehaviourNutritionManagement

EnvironmentPhysicalChemical

Poor ventilation, enclosed buildingStuffy micro-environmentAmmonia building-upDust

Chicken respiratory infections…• Infectious

Viruses BacteriaChlamydiaMycoplasmasFungi/yeastsParasites

- protozoa- worms

• Non-infectiousPhysiological/malfunctionTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

Avian influenza– H5/H7Newcastle disease

Infectious bronchitis virus (IB) LPAI – H9N2 Infectious laryngotracheitis (ILT) Avian metapneumovirus (aMPV) Fowl pox (FP)

Chicken respiratory infections…• Infectious

Viruses BacteriaChlamydiaMycoplasmasFungi/yeastsParasites

- protozoa- worms

• Non-infectiousPhysiological/malfunctionTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

E coli Pasteurella multocida (F cholera) Avibacterium paragallinarum (IC) Ornithobacterium rhinotracheale (ORT) Salmonella sp Others

Chicken respiratory infections…• Infectious

Viruses BacteriaChlamydiaMycoplasmasFungi/yeastsParasites

- protozoa- worms

• Non-infectiousPhysiological/malfunctionTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

M. gallisepticum (Mg)M. synoviae (Ms)

E coli Pasteurella multocida (F cholera) Avibacterium paragallinarum (IC) Ornithobacterium rhinotracheale (ORT) Salmonella sp Others

Chicken respiratory infections…• Infectious

Viruses BacteriaChlamydiaMycoplasmasFungi/yeastsParasites

- protozoa- worms

• Non-infectiousPhysiological/malfunctionTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

Aspergillus fumigatus

Chicken respiratory infections…• Infectious

Viruses BacteriaChlamydiaMycoplasmasFungi/yeastsParasites

- protozoa- worms

• Non-infectiousPhysiological/malfunctionTumoursBehaviourNutritionManagementEnvironmentPhysicalChemical

Syngamus tracheaCryptosporidium baileyi

Chicken respiratory disease – clinical signs and lesions

- Nasal and ocular discharges- Wheezing, rales- Sneezing, Coughing- Gasping- Head-shaking/scratching- Mortality and morbility, variable

Conjunctivitis Sinusitis Rhinitis Laryngitis Tracheitis

Chicken respiratory disease – clinical signs and lesions

- Abdominal breathing- Wheezing

Tracheal plug Pneumoniae Lung congestion Airsacculitis

Mild Moderate Severe

Fibrinous airsacculitis Yellowish spots (fungi)

Chicken respiratory infections– differential diagnoses

• Signs and lesions similar for the listed pathogens….

• except:– HPAI, high sudden mortality, rapid morbidity– NDV, high sudden mortality, rapid morbidity*– LPAI, variable mortality, rapid morbidity *– IBV, variable mortality, rapid morbidity *– aMPV, low mortality, low morbidity *– ILT, variable mortality, low morbidity *– Mycoplasmas and other bacterial infections, variable

mortality and low morbidity *

• Also for ILT, coughing with blood and haemorrhagic tracheitis, characteristic

Chicken respiratory infections– differential diagnoses

Chicken respiratory diseases –differential diagnosesFor Mg + Ms, similar signs, often mild and prolonged, except

exacerbation when complicated with other pathogens

Mg MsYear 1935/

19601960/1964

Respiratory disease +++ ++Reproductive disease +++ +++

Musculoskeletal + +++

Diagnostic priorities +++ +++

Ms becoming as important as Mg - worldwide

Mg MsYear 1935/

19601960/1964

Respiratory disease +++

Reproductive disease +++

Musculoskeletal + +++

Diagnostic priorities +++

Feberwee, et al., 2009

Agent Resp GIT Neu Repr Renal M/S etc

HPAI √ √ √ √ √ √

LPAI √ √ √ √ √

NDV √ √ √ √ √ √

IBV √ ? √ √ √?

ILTV √

aMPV √ √ √

FP √ √ √

Respiratory infections = respiratory + systems (normally)

Agent Resp GIT Neu Repr Renal M/S etc

Mg √ √

Ms √ √ √

PM √ √ √

AvP √

ORT √

Ec √ √ √ √ √ √

Sal √ √ √ √ √ √

Respiratory infections = respiratory + systems (normally)

Agent Resp GIT Neu Repr Renal M/S etc

Syntr √

Crypb √ √

Respiratory infections = respiratory + systems (normally)

AgentSerology

ELISA HI SNT Pen-site

HPAI √ √ √ √LPAI √ √ √NDV √ √ √IBV √ √ √ILTV √ √

aMPV √ √

Respiratory infectionslaboratory diagnosis - serology

• Availability• Cost• Speed(delivering results)• Assay

• Convenience • User friendly• Sensitivity• Specificity

• Sample collection….• Antigen detection

• Culture, isolation and identification• Bacteria and fungal• Mycoplasmas• Viruses• Parasites (identification)

• Molecular detection, genotyping or finger-printing• Conventional PCR• Real-time PCR

Virus isolation versus PCRlaboratory diagnosis – antigen detection

Direct demonstration• EM• Immunostaining

• Non-specific versus suggestive findings• Some differential is possible but non-confirmatory• In the case of ILT

• Intranuclear inclusion bodies in the mucosa

Histopathologylaboratory diagnosis: general versus suggestive

Control and prevention: respiratory diseases(outline)

Biosecurity

ChickensManagement

Vaccine &Vaccination; strategic medication;

health tonic

Conclusions Consider non-infectious prior to the infectious

causes Investigate the potential ‘underlying’ issues… Laboratory support essential for narrowing respiratory diagnoses Serology most preferred, however, best to complement with antigen detection Molecular detection preferred but should be companied with culture, isolation and identification

Thanks for your kind attention…Email:gana@liv.ac.uk

Acknowledgments