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The proper diagnosis of poultry diseases depends on three important factors:
Identification of vital organs and body structure.
Knowledge of disease symptoms and lesions.
A systematic plan for examining the bird's body.
This publication outlines a plan for examining sick birds. Become
familiar with the normal appearance of birds and their organs by
following the procedure outlined in this publication on one or more
healthy birds. Examining a healthy bird can help you learn what to look
for in sick birds.



It is especially important that you identify affected organs and
tissues before seeking a diagnosis from poultry specialists. A
treatment cannot be suggested unless an accurate history and list of
symptoms and lesions are known.


Flock History

Poultry diseases must be considered as diseases of the flock rather
than individual diseases. Symptoms in a few individual birds are
usually an indication of a more serious flock-wide problem. It is
important that an accurate flock history be recorded. The source of
many diseases can be determined from this flock history.
A complete flock history includes the following:

name and address of the owner
number of birds in the flock
breed, strain, and age of the birds.
Management information consists of the following:

hatchery source
type of operation
feeding program
a complete vaccination history.
Information on the illness includes the following:

the date the illness was first observed
severity and number of birds affected
number of birds dying
medication history.
Final remarks of disease in previous flocks and any unusual problems or conditions should be included.


External Examination

Before examining the bird internally, observe and inspect the bird for
external symptoms. Note the general condition and fleshing (presence of
meat on the bone) of the bird. Check the condition of the skin, and all
natural body openings (nasal openings, mouth, ears, and vent). Examine
the head, eyes, comb, and wattles for evidence of swelling, canker
lesions, unusual discharge or coloration.
Look for signs of lameness, paralysis, or general weakness. Inspect the
affected areas for abnormalities or swelling that can give a clue to
the cause. If you observe a partial or complete paralysis, note the
position the bird assumes. It is often an indicator of the cause of
illness. Inspect the bird for external parasites such as mites, lice,
ticks, and fleas.


Euthanasia

Starting a flock treatment early often saves more birds than delaying
treatment until the first birds die. For disease diagnosis it is often
best to kill a sick bird showing typical symptoms of the flock. Healthy
birds from a sick flock contribute nothing when examined.
The most humane methods of killing the bird are injecting sodium
pentobarbitol, electrocution, and dislocation of the head from cervical
vertebrae. The first two methods are usually too expensive or dangerous
for common usage. Cervical dislocation is the most practiced method of
killing birds for examination.

To dislocate the head from the vertebra, direct the bird's head toward
you. Grasp the bird's head with a handshake grip. Place your thumb
behind the head at the base of the skull, all allow the remaining
fingers to extend under the throat. Hold the bird's feet with the other
hand and stretch the bird until you feel the head separating from the
neck vertebrae. You will probably need to bend the head back slightly
while stretching the bird.

Be careful to stop pulling when the spine separates or the head may be
pulled off. The bird dies immediately when the spine separates.

The killing of small birds such as chicks, poults, or parakeets is
often difficult because their heads are small and hard to grasp. The
vertebrae may be separated by applying pressure with scissor handles at
a joint between two vertebrae. It is best to apply pressure on each
side of the neck rather than at the throat and back of the neck. This
avoids unnecessary damage to the gullet and windpipe. Large chickens
and turkeys may be killed this same way, using burdizzos instead of
scissor handles. A burdizzo is a plier-like tool used when castrating
cattle and other farm animals.

It is important that you are familiar with the organs you will see.
Become familiar with the following anatomy before examining sick birds.




Poultry Anatomy
Respiratory System
Each nasal opening leads into a nasal cavity that is connected to sinus
cavities around each eye. A split in the roof of the mouth provides an
air passage between the nasal cavities and the lower respiratory
system. The nasal cavities filter the air before it enters the lungs.

The larynx is located at the rear of the mouth. It is the structure
connecting the trachea (windpipe) and gullet. The trachea is a tube
that separates into two bronchial tubes, with each tube attached to a
lung. The trachea and bronchial tubes are supported by rings of
cartilage that prevent the tubes from collapsing.

The lungs are located near the vertebra and lay closely against the
ribs. They resemble bright red sponges because of the abundant blood
supply. Bird lungs are smaller in proportion to body size than other
animals. Though small, the lungs are aided by an extensive system of
air sacs found only in birds.

The air sacs are thin membrane sacs that surround the internal organs.
They are used as reserve air space to increase lung capacity. When the
bird's body is opened, the air sacs appear as clear thin membranes
among the body organs. They are among the first sites affected by
respiratory diseases.

Digestive System

The mouth is connected to the rest of the digestive system by a
thin-walled tube called the esophagus or gullet. The lower portion of
the esophagus forms a pouch called the crop. It functions as a
temporary storage site for food. The lower end of the esophagus is
attached to the bird's stomach.

The bird stomach has two parts -- proventriculus and gizzard. The
proventriculus is the slightly enlarged area between the esophagus and
gizzard. When opened it has a deeply textured appearance. The gizzard
has a tough membrane inner lining firmly attached to the muscular outer
part.

The lower end of the gizzard is attached to the upper end of the small
intestine. The first portion of the small intestine is the duodenum. It
is held in a loop-like position by the pancreas. The pink pancreas is
located between and attached to the portions of the intestine forming
the loop.

The lower portion of the small intestine is attached to a membrane
called the mesentery. This mesentery is laced with many blood vessels
that enter and exit the small intestine. When opened, the lining of the
small intestine has a soft, velvety texture.

Two large closed pouches called ceca are attached at the lower end of
the small intestine. Bacterial action in the ceca helps break down some
of the undigested food passing through the intestine. The ceca in adult
chickens are usually about four or six inches long. When opened they
contain a darker brown, more pasty material than the intestines.

Following the ceca, the small intestine changes into the large
intestine. This large intestine is a short section of intestine that
connects the small intestine and cloaca, or chamber where the
digestive, urinary, and reproductive systems meet. The external opening
of the cloaca is called the vent.

The liver is a large brown organ located in the front portion of the
body cavity (thorax). It is the largest organ in the body. It has two
large lobes separated by a thin membrane. Its function is to produce
digestive fluids and filter toxic wastes from the blood. A digestive
fluid produced in the liver (bile) is stored in the gall bladder. This
gall bladder is a small, greenish pouch attached to the liver. A bile
duct between the liver and small intestine directs the bile to the
intestine.

Urinary, Reproductive, and Vascular Systems

The urinary system in birds consists of kidneys and ureters. The kidney
is a dark brown organ located in a pocket of the pelvic bones. There
are two kidneys in each bird, and each kidney has a ureter. The ureter
is a tube that passes the urinary wastes from the kidney to the cloaca.


The reproductive organs include the ovary and oviduct in the female and
the testes in the male. The hen usually has only one ovary and oviduct.
The ovary is a group of egg yolks in various stages of development and
is located in the area of the kidneys. Some yolks may not be seen,
while some in the laying hen may be the size of normal egg yolks. The
oviduct in mature hens appears as a coiled tube extending from the area
of the ovary to the cloaca. In immature females the ovary and oviduct
may not be easily seen.

The reproductive system of the male consists primarily of the two
testes. The testes are oval organs located between the lungs and
kidneys. Ducts through which sperm pass (ductus deferens) extend from
each testis to the cloaca.

Vascular organs consist primarily of the heart and spleen. The
four-chambered heart is located above the liver. The spleen is a
spherical, reddish-brown organ located between the liver and gizzard.
Its primary purpose is removing unhealthy blood cells, micro-organisms,
and debris from the blood system.


Necropsy Procedure

A necropsy is an examination of a dead animal. The only tool necessary
to perform a necropsy is a sharp cutting utensil, but several good
quality tools are recommended. A sharp pair of surgical type scissors
and a scalpel, or knife, make it easier to cut the necessary tissues. A
pair of heavy shears help when cutting through bones. Although few
poultry disease can infect people, it is recommended that you wear
disposable plastic gloves during the necropsy procedure.
Begin the necropsy by washing the dead bird with detergent water. This
removes any foreign material and holds down the feathers. Place the wet
bird on a flat surface with breast side up and head directed away from
you. The following steps are numbered to make it easier to follow the
procedures.


Remove upper portion of the beak by cutting through the nasal cavities
and turbinated bones. Turbinated bones are membrane-covered plates on
the walls of the nasal chambers. This lets you observe the upper
respiratory areas for the presence of infection. Squeeze the turbinate
area and note if excessive matter oozes from the area. Check the eyes
for inflammation (unusual reddening), mucus, or discoloration.
Insert one scissor blade into the mouth and cut through one corner of
the mouth. Extend the cut down the neck so the interior of the gullet
is exposed. Examine the mouth and larynx for abnormalities that
indicate pox, mycosis, or other disease. Scan the gullet for tiny
nodules (bumps) or signs of injury by foreign materials.
Cut the larynx and trachea from the mouth and open the trachea
lengthwise. Examine its interior for excessive mucus, blood, or cheesy
material.
Make an incision in the abdominal skin just below the tip of the breast
cartilage. Extend the cut around the body on each side. Grasp the upper
edge of the cut skin and bluntly peel the skin over the breast. This
exposes the breast muscles. Examine them for conditioning and the
presence of hemorrhages (sites of prior bleeding in the muscle).
Cut the skin on the abdomen where the legs join the body. Place a hand
on each leg and press down and out until the femoral joints dislocate
and the legs lie flat on the table. Tear the skin from the legs and
check for small pin-point hemorrhages.
Make an incision through the abdominal muscles just below the tip of
the breast bone. Do not cut too deep, or you may cut internal organs.
Extend the cut toward the back and then angle toward the point of wing
attachment on each side. You must cut through the ribs in order to
complete this cut. Push the breast toward the head and dislocate the
shoulder joints. Cut through the shoulder joints and remove the breast
from the carcass.
Observe the condition of the air sacs. The membranes are often cloudy and covered with mucus in diseased birds.
Examine the liver for unusual swelling, lesions, hemorrhages, or
abnormal coloration. Make incisions into the liver and check for scar
tissue and necrotic (dead) tissue. Check the spleen for hemorrhages,
lesions, and swelling. Check for a cloudy, fluid-filled sac surrounding
the heart.
Remove the liver, heart, and spleen so the digestive system is exposed.
Check the digestive system for abnormal nodules, tumors, or
hemorrhages. Sever the gullet near the mouth and remove the entire
digestive system. You can cut the lower intestine behind the ceca for
complete removal.
Cut into the crop. Note if the contents are sour smelling. Wash
contents from the crop and examine the lining for thickened, patch-like
areas or necrotic ulcers. Check for capillary worms by making a small
cut and slowly tearing the crop wall as if it were a piece of paper.
Capillary worms appear as small, hair-like fibers extending across the
base of the tear.
Open the proventriculus, the slightly enlarged area between the
esophagus and gizzard, and note any hemorrhages or a white coating on
the lining.
Open the gizzard and examine the lining for unusual roughness or
lesions. Determine if the lining is separating from the underlying
muscles.
Slit the intestine lengthwise and examine contents for the presence of
worms, free blood, and excess mucus. Check the lining for inflammation,
ulcers, or hemorrhagic areas. If unusual conditions exist, note in
which one-third portion of the intestine the conditions are located.
Open the ceca and examine the contents. Look for cheesy cores and
small, cecal worms. If you find blood, wash and examine the lining for
scarring and cecal worms.
Check the reproductive organs (ovary and oviduct in females, testes and
ductus deferens in males) for abnormalities before removing them from
the body.
Examine the kidneys and ureters for unusual swelling or the presence of whitish salt deposits.
Check the sciatic nerve extending to each leg for swelling. Once you
remove the kidneys, you can see this nerve as a small white fiber
stretching from the spinal cord along the femur into the lower leg.
Also check the brachial nerve extending from the spine, along each
humerus (upper wing bone), to the wing tip.
Observe the lungs and bronchial tubes for lesions and unusual accumulation of mucus.
You can make notes on history, symptoms, and lesions until you are
familiar enough to diagnose diseases without consulting references. It
is recommended that you follow all the procedures in this publication.
Often two or more diseases can infect a bird and the symptoms may be
confusing. Check all affected areas before making a diagnosis and
administering a treatment.


Diagnosis and Treatment

After you have listed the symptoms and lesions, refer to a good poultry
disease manual to determine the proper diagnosis. You can get a disease
manual and helpful advice from your county agent or Extension poultry
specialists.
When you or a specialist diagnose a disease, a specialist will
recommend a treatment. Take care to administer the medication using the
proper dosage, method of application, and the period of recommended
time. Becoming familiar with disease symptoms and lesions and following
the proper diagnostic procedures will eliminate the difficulty of
diagnosing many poultry diseases.


Flock History

Owner_____________________________________________ _________________________
Address_______________________________________ Phone No.____________________

Number in Flock________________ Breed___________________ Age________________

Hatchery Source____________________________________________ ________________

Type of operation (floor, cage, range, etc.)_______________________________________

Feeding program___________________________________________ __________________

Vaccination History___________________________________________ _______________



Date Illness First Seen______________________________________________ __________

No. Affected by Illness__________________ No. Dead_____________________________

Medication________________________________________ _________________________



Symptoms and Remarks___________________________________________ ___________

__________________________________________________ _________________________

__________________________________________________ _________________________

__________________________________________________ _________________________


External Examination
Condition of Bird______________________________________________ _______________

Comb and Wattles___________________________________________ _________________

Eyes, Ears, Mouth_____________________________________________ ______________

Vent Opening___________________________________________ _____________________

External Parasites_________________________________________ ___________________


Necropsy Results
Female____________________ Male_____________________

Head

Eyes________________________ Nasal Cavities__________________________________

Mouth_____________________________________________ ________________________

Respiratory and Circulatory Systems

Larynx and Trachea (Windpipe)________________________________________ ________

Lungs and Bronchial Tubes_____________________________________________ _______

Air Sacs______________________________________________ ______________________

Heart_____________________________________________ __________________________

Digestive System and Accessory Organs

Gullet (Esophagus)_______________________________________ __________________

Crop______________________________________________ ________________________

Proventriculus and Gizzard___________________________________________ _________

Small Intestine_________________________________________ ______________________

__________________________________________________ _________________________

Ceca______________________________________________ _______________________

Cloaca____________________________________________ ________________________

Liver_____________________________________________ _________________________

Spleen____________________________________________ ________________________

Excretory and Reproductive Systems

Kidneys and Ureters___________________________________________ ______________

Ovary and Oviduct___________________________________________ ________________

Testes or Ductus Deferens__________________________________________ __________

Muscles

Breast____________________________________________ _____________

Legs______________________________________________ ____________

Nervous System

Brachial Nerve_____________________________________________ ________________

Sciatic Nerve_____________________________________________ __________________

Diagnosis

__________________________________________________ ________

__________________________________________________ _________________________

__________________________________________________ _________________________

Treatment

_________________________________________________