This document summarizes several common respiratory diseases that affect poultry: aspergillosis, avian cholera, avian influenza, fowl pox, infectious bronchitis, infectious laryngotracheitis, mycoplasma gallisepticum, and Newcastle disease. For each disease, the summary includes the causative agent, clinical signs, diagnosis, and treatment or prevention methods. The diseases can cause respiratory distress, decreased feed intake, egg production drops, and mortality. Accurate diagnosis is important for effective treatment and control of spread. Improving ventilation, sanitation measures, and vaccination are recommended for prevention depending on the specific disease.

1. Introduction
Poultry may become infected with several
types of respiratory illnesses caused by
viruses, bacteria, fungi, and parasites.
Clinical signs of these illnesses often look
very similar. However, successful
treatment and prevention of these diseases
depends on an accurate diagnosis. Some of
the common respiratory diseases are
explained briefly
Aspergillosis (Brooder
Pneumonia)
Cause: Common fungus called
Aspergillus fumigatus, sources of which
may include moldy, wet feed; wet
bedding; or mold on hatching eggs.
Infection occurs when birds inhale large
numbers of fungal spores, producing
severe inflammation in birds’ lungs, air
sacs, and sometimes other tissues
Clinical signs: Aspergillosis occurs as
an acute disease of young birds and a
chronic disease in mature birds. Young
birds have trouble breathing and gasp for
air. Characteristi- cally, there are no rales
or respiratory sounds associated with
aspergillosis. Feed consumption decreases.
Occasion- ally there is paralysis or
convulsions caused by the fungal toxin.
Mortality in young birds averages 5–20
percent, but may be as high as 50 percent.
Mature birds also have respiratory distress,
reduced feed consumption, and may have
a bluish and dark color of the skin
(cyanosis). Nervous disorders, such as
twisted necks, may occur in a few birds
(see Table 1). Mortality in mature birds is
usually less than 5 percent..
Diagnosis:Respiratory tract cultures
and/or microscopic examination of the
affected tissues.
Treatment and prevention
There is no cure for infected birds. The
spread can be controlled by improving
ventilation, eliminating the source of the
infection, and adding a fungistat
(mycostatin, mold curb, sodium or calcium
propionate, or gentian violet) to the feed
and/or copper sulfate or acidified copper
in the drinking water for 3 days. The litter
can be sprayed lightly with an oil-base
germicide to control dust and air
movement of fungal spores
Avian Cholera (Pasteurella
multocida)
Respiratory Diseases of Poultry

2. Cause: Bacterial infection from
Pasteurella multocida, which can be
acquired from exposure to sick wild
waterfowl or rodents in the poultry area or
through bite injuries from predators that
carry these bacteria in their saliva. The
disease can be further spread through
fighting in the birds and may cause
pneumo- nia, abscesses in multiple tissues,
and often high death loss.
Clinical signs: Fowl cholera usually
strikes birds older than 6 weeks of age. In
acute outbreaks, dead birds may be the
first sign. Fever, reduced feed
consumption, mucoid discharge from the
mouth, ruffled feathers, diarrhea, and
labored breathing may be seen. As the
disease progresses birds lose weight,
become lame from joint infections, and
develop rattling noises from exudate in air
passages. As fowl cholera becomes
chronic, chickens develop abscessed
wattles and swollen joints and foot pads.
Diagnosis: Bacteria must be cultured in a
laboratory from blood samples, abscesses,
or dead birds.
Treatment and prevention: Treat the
flock with an appropri- ate antibiotic
(ideally based on culture and drug
sensitivity information) for at least 10
days. Predator and rodent control is also
necessary. Pick up and dispose of dead
birds. Clean up and disinfect the coop
Avian Influenza
Cause: Type A influenza virus of birds,
which is most often present in wild and
domestic waterfowl and shore birds.
Infection is occasionally transmitted to
poultry. Two forms of the illness occur:
highly pathogenic avian influenza (HPAI)
and low pathogenic avian influenza
(LPAI). LPAI sometimes produces
minimal illness in infected birds, but HPAI
is very lethal to chickens, turkeys, and
upland gamebirds. Clinical signs are
highly variable but may include
respiratory disease, drops in egg
production, swol- len head, hemorrhages
on the body and comb, and sometimes
high death loss
• Diagnosis: Antibodies can be detected
with a blood test. Tests that detect the
virus from respiratory and cloacal swabs
are also available/
• Treatment and prevention: There
is no effective treatment for avian
influenza. With the mild form of the
disease, good husbandry, proper nutrition,
and broad spectrum antibiotics may reduce
losses from secondary infections.
Recovered flocks continue to shed the
virus. vaccination program used in
conjunction with a strict quarantine has
been used to control mild forms of the
disease. With the more lethal forms, strict

3. quarantine and rapid destruction of all
infected flocks remains the only effective
method of stopping an avian influenza
outbreak. If you suspect you may have
Avian Influenza in your flock, even the
mild form, you must report it to the state
veterinarian’s office. A proper diagnosis
of avian influenza is essential. Aggressive
action is recommended even for milder
infections as this virus has the ability to
readily mutate to a more pathogenic form.
Fowl Pox Infection
Cause: Birds become infected with the
pox virus through contact with sick birds
or infected scabs in the environment.
Mosquitos can also transmit fowl pox.
Clinical signs: There are two forms of
fowl pox. The dry form is characterized by
raised, wart-like lesions on unfeathered
areas (head, legs, vent, etc.). The lesions
heal in about 2 weeks. If the scab is
removed before healing is complete, the
surface beneath is raw and bleeding.
Unthriftiness and retarded growth are
typical symptoms of fowl pox. In laying
hens, infection results in a transient
decline in egg production
• Diagnosis: Typical nodules and scabs
can be seen on featherless tracts of skin on
the face, wing web, and feet, and often
take 3 to 4 weeks to heal and fall off.
Nodules can sometimes de- velop in the
mouth and trachea. This form, called “wet
pox,” is difficult to recognize and may
cause affected birds to die from
suffocation.
• Treatment and prevention:
Keep a closed flock (no new birds of any
age or species introduced to the present
flock from outside sources) and control
mosquitoes. Clean up and disinfect the
coop. A very effective vaccine is available
that can prevent the illness or stop the
existing infection from spreading if
detected early.
Infectious bronchitis
Cause: An avian coronavirus. The dis-
ease spreads very rapidly and causes
coughing, egg production drops, and
sometimes death loss in very young
chickens. After the initial infection, thin-
shelled eggs or eggs with wrin- kled shells
may be seen.
Clinical signs: The severity of
infectious bronchitis infec- tion is
influenced by the age and immune status
of the flock, by environmental conditions,
and by the presence of other diseases.
Feed and water consumption declines.
Affected chickens will be chirping, with a
watery discharge from the eyes and

4. nostrils, and labored breathing with some
gasping in young chickens. Breathing
noises are more noticeable at night while
the birds rest. Egg production drops
dramatically. Production will recover in
5or 6 weeks, but at a lower rate. The
infectious bronchitis virus infects many
tissues of the body, including the
reproductive tract. Eggshells become
rough and the egg white becomes watery.
• Diagnosis: Blood test. Some animal
laboratories can attempt isolation of the
virus from necropsy specimens.
Treatment and prevention: There is
no specific treatment for infectious
bronchitis. Antibiotics for 3–5 days may
aid in combating secondary bacterial
infections. Raise the room temperature 5°F
for brooding-age chickens until symptoms
subside. Baby chicks can be encouraged to
eat by using a warm, moist mash
.Vaccines are also available.
Infectious Laryngotracheitis (ILT)
• Cause: An avian herpesvirus. Infected
chickens develop severe respiratory
distress and may cough up bloody mucus.
High death loss may be seen. Recovered
birds may remain virus carriers and
continue to spread the infection among
susceptible chickens.
Clinical signs: The clinical sign usually
first noticed is watery eyes. Affected birds
remain quiet because breathing is difficult.
Coughing, sneezing, and shaking of the
head to dislodge exudate plugs in the
windpipe follow. Birds extend their head
and neck to facilitate breathing (commonly
referred to as “pump handle respiration”).
Inhalation produces a wheezing and
gurgling sound. Blood-tinged exudates and
serum clots are expelled from the trachea
of affected birds. Many birds die from
asphyxiation due to a blockage of the
trachea when the tracheal plug is freed
• Diagnosis: High death loss and
coughing up blood (if present) are very
suggestive of ILT. Submit sick or dead
birds to the Animal Diagnostic
Laboratory.
• Treatment and prevention:
Incinerate dead birds, administer
antibiotics to control secondary infection,
and vaccinate the flock. Mass vaccination
by spray or drinking water method is not
recommended for large commercial or
caged flocks. Individual bird
administration by the eye-drop route is
sug- gested. Follow manufacturers
instructions. In small poultry flocks, use a
swab to remove plug from gasping birds,
and vaccinate by eye-drop method.A
tissue-culture-origin vaccine should be
used.
Mycoplasma gallisepticum(MG) •

5. Cause: This bacteria infects chickens,
turkeys, and upland game birds. Clinical
signs in- clude nasal discharge, infected
sinuses and air sacs, pneumonia, and a
drop in egg production. Turkeys are the
most vulnerable to infection, while
chickens sometimes carry this bacteria
without showing signs. Spread by bird-to-
bird contact or contact with infectious
respiratory secretions. Once in- fected, a
bird remains infected for life. Infected
breeders also transmit this bacteria into the
hatching egg, causing chicks to hatch with
the infection.
• Diagnosis: Clinical signs, blood
testing, and testing for pres- ence of the
organism.
• Treatment and prevention: The
effects of the disease can be reduced with
certain antibiotics. Vaccines are also
available. For prevention, keep a closed
flock and only purchase birds that have
tested negative
 Clinical signs: There are three forms of
Newcastle disease— mildly pathogenic
(lentogenic) , moderately pathogenic
(mesogenic) and highly pathogenic
(velogenic). Newcastle disease is
characterized by a sudden onset of clinical
signs which include hoarse chirps , watery
discharge from nostrils, labored breathing
(gasping), facial swelling, paralysis,
trembling, and twisting of the neck (sign
of central nervous system involvement).
Mortality ranges from 10 to 80 percent
depending on the pathogenicity. In adult
laying birds, symptoms can include
decreased feed and water consumption and
a dramatic drop in egg production
 Transmission: The Newcastle virus can
be transmitted short distances by the
airborne route or introduced on
contaminated shoes, caretakers, feed
deliverers, visitors, tires, dirty equipment,
feed sacks, crates, and wild birds.
Newcastle virus can be passed in the egg,
but Newcastleinfected embryos die before
hatching. In live birds, the virus is shed in
body fluids, secretions, excreta, and
breath.
Treatment and Prevention : There is
no specific treatment for Newcastle disease.
Antibiotics can be given for 3–5 days to
prevent secondary bacterial infections .For
chicks, increasing the brooding temperature
5°F may help reduce losses.: Prevention
programs should include vaccination (see
publication PS-36, Vaccination of Small
Poultry Flocks), good sanitation, and
implementation of a comprehensive
biosecurity program.
 Infectious Coryza

6. Synonyms: roup, cold, coryza Species
affected: chickens, pheasants, and guinea
fowl. Common in game chicken flocks.
 Clinical signs: Swelling around the
face, foul smelling, thick, sticky discharge
from the nostrils and eyes, labored
breathing, and rales (rattles—an abnormal
breathing sound) are common clinical
signs. The eyelids are irritated and may
stick together. The birds may have
diarrhea and growing birds may become
stunted .Mortality can be as high as 50
percent, but is usually no more than 20
percent. The clinical disease can last from
a few days to 2–3 months, depending on
the virulence of the pathogen and the
existence of other infections such as
mycoplasmosis.
 Transmission: Coryza is primarily
transmitted by direct bird-to-bird contact.
This can be from infected birds brought
into the flock as well as from birds which
recover from the disease which remain
carriers of the organism and may shed
intermittently throughout their lives. Birds
risk exposure at poultry shows, bird
swaps.
 Treatment: Water soluble antibiotics or
antibacterials can be used.
Sulfadimethoxine (Albon®, Di-Methox™)
is the preferred treatment. If it is not
available, or not effective, sulfamethazine
(Sulfa-Max®, SulfaSure™), erythromycin
(gallimycin®), or tetracycline
(Aureomycin®) can be used as alternative
treatments. Sulfa drugs are not FDA
approved for pullets older than 14 weeks
of age or for commercial
 Newcastle disease
 Clinical signs: There are three forms of
Newcastle disease— mildly pathogenic
(lentogenic) , moderately pathogenic
(mesogenic) and highly pathogenic
(velogenic). Newcastle disease is
characterized by a sudden onset of clinical
signs which include hoarse chirps , watery
discharge from nostrils, labored breathing
(gasping), facial swelling, paralysis,
trembling, and twisting of the neck (sign
of central nervous system involvement).
Mortality ranges from 10 to 80 percent
depending on the pathogenicity. In adult
laying birds, symptoms can include
decreased feed and water consumption and
a dramatic drop in egg production
 Transmission: The Newcastle virus can
be transmitted short distances by the
airborne route or introduced on
contaminated shoes, caretakers, feed
deliverers, visitors, tires, dirty equipment,
feed sacks, crates, and wild birds.
Newcastle virus can be passed in the egg,
but Newcastleinfected embryos die before

7. hatching. In live birds, the virus is shed in
body fluids, secretions, excreta, and
breath.
 Treatment and Prevention : There
is no specific treatment for Newcastle
disease. Antibiotics can be given for 3–5
days to prevent secondary bacterial
infections .For chicks, increasing the
brooding temperature 5°F may help reduce
losses.: Prevention programs should
include vaccination (see publication PS-
36, Vaccination of Small Poultry Flocks),
good sanitation, and implementation of a
comprehensive biosecurity program.