Clinical signs:

Respiratory signs in poultry include runny watery eyes, swollen sinuses, nasal discharge, wheezing, sneezing, gurgling/rattling, gasping and mortality. Cyanosis, considering the spare capacity of the avian respiratory system is indeed a sign of a significantly acute or long-standing significant respiratory malfunction.

The differential diagnosis of respiratory diseases in poultry includes the following diseases Bacterial - Coryza, Mycoplasma gallisepticum (MG), Pasteurella multocida (Fowl cholera), E. coli, Strep, Chlamydiosis, Ornithobacterium rhinotracheale.

o   Viral -ILT, IBV, AIV, NDV, F pox, Pneumovirus, Mareks disease, Leucosis

o   Fungal -Aspergillosis

o   Parasitic - Syngamus, trichomoniasis.

o   Nutritional - Vit A

1.    Avian influenza (AIV ) Synonyms: AI, flu, influenza, fowl plague

Etiology: Orthomyxovirus

Respiratory signs in LPAI incidents are low and may be associated with concurrent bacterial or other viral infections.

2.    Newcastle Disease

Etiology: Avian Paramyxovirus -1 and Newcastle disease 

  Avian Paramyxoviruses- 2 and 3.

Neurotropic velogenic - high mortality; respiratory and nervous signs predominate;

Mesogenic - low mortality; respiratory signs usually predominate.

Respiratory signs including sinusitis and runny eyes were evident in a layer of flocks without nervous signs or before the emergence of nervous signs. Depression, nervous signs; ataxia, paralysis, opisthotonos and head nodding, increased mortality, and changes to eggshell color.

Gross pathology showed tracheal hemorrhage, airs sacculitis and congestion similar to some cases of ILT

Control:

 I. Timely vaccination with live and/or inactivated (killed) vaccine is the only reliable control method.

 2. Vaccination alone is not sufficient to control ND. It must therefore be accompanied by good hygiene, good management, and good biosecurity practices.

3. ILT Infectious laryngotracheitis

Etiology: herpes virus

ILT may appear in 2 forms; the severe form with dyspnea, gasping, coughing, blood-stained mucus, cheesy core, and mortality, and the milder form where clinical signs include watery eyes, swelling of the sinuses, nasal discharge, possibly hemorrhagic, conjunctivitis, and mortality. In mild forms, conjunctivitis may be the only gross pathology present. In either the severe or the milder forms, ILT requires consideration of viral and bacterial differential. The presence of cheesy cores in the tracheal lumen is almost pathognomonic of ILT.

4. Fowl pox

The disease occurs in the cutaneous (classical) form and the diphtheritic (wet pox) form and the combination of both in the same flock or even in the same bird. The wet pox form is more associated with respiratory signs than the classical cutaneous form. In the wet pox form, yellowish lesions appear on the mucous membranes of the mouth, oesophagus, or the trachea and respiratory signs can be evident and may either resemble ILT or Coryza/CRD.

Flock mortality ranges from low to 50% depending on the species of birds, their age, the virulence of the virus and the nature of the lesions.

Control:

 I. Fowl pox can be prevented by vaccination. Therefore, preventive vaccination using a live vaccine is the most successful control method. Even when an outbreak of fowl pox has been diagnosed, it is advisable to vaccinate the flock immediately to stop spread of infection.

 2. Precautions should be taken to minimize the spread of the vaccine virus, both on the birds and in the environment. Being a live virus, it is capable of spreading the disease.

 3. Carcasses or affected birds should be buried or burnt, and house should be disinfected.

5. Pneumonitis infection (Turkey Rhinotracheitis/Swollen Head Syndrome)

Species: turkeys and chickens.

Clinical signs and lesions: In young turkeys - sneezing. Rales and nasal discharge, conjunctivitis, and swelling of the infraorbital and submandibular areas can be seen.

In laying turkey flocks a drop in production may occur along with respiratory distress. Morbidity is high whereas mortality may vary being usually higher in young poults. In chickens: Pneumovirus may be involved in the so called "swollen head syndrome" (SHS)- affected chickens may show swelling of the periorbital and infraorbital sinuses, torticollis, cerebral disorientation and depression. Marked egg production losses can be associated with SHS.

In cases of SHS, apart from oedema of the head, also purulent or caseous subcutaneous exudate can be found. Rhinitis, tracheitis and sinusitis are frequently noted in both chicken and turkeys, E. coli infection is often involved.

6. Infectious bronchitis (IB)

Etiology: Corona-virus is the causal agent. Several different serotypes of IB virus are known to exist.

Species affected: Chickens are the main species susceptible to IB virus although reported occasionally in pheasants where it causes high mortality.

Clinical signs: In young chicks less than 6-8 weeks of age IB virus infection causes cheesy exudates in the bifurcation of the bronchi, thereby causing asphyxia, and severe respiratory distress, similar to ILT. Runny eyes and swollen sinuses may also be present.

In older chickens, IB does not cause mortality. Respiratory signs may be present but are usually relatively mild or absent. Egg production is affected and deformed eggs with pale shell eggs, soft-shelled, misshapen eggs and wrinkled shells will often be laid. The internal quality of the egg, especially the albumen more watery than normal may be observed.

Control:  Both live and killed vaccines are available of value. 

7. Marek's disease and leucosis

Etiology: Herpesvirus

Although not the primary manifestation of Marek's disease, tumor formation localized in some areas or organs, or those affecting some of the nerves may lead to the presence of respiratory signs.