Zagazig University Avian Necropsy Guide

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With the bird in dorsal recumbency, the walls of the right atrium and ventricle are
positioned on top. After death, the atria often expand with blood and can appear quite
enlarged. The great vessels can be seen entering the base of the heart. The heart
muscle should be reddish-brown in color. A variable amount of fat will be present in
the coronary grooves. If the bird is emaciated, this fat may be absent or have
undergone serous atrophy, resulting in a gelatinous, wet appearance. Look for any
external lesions on the epicardial surface of the heart or on the surrounding fat



The heart muscle should be reddish-brown in color. A variable amount of fat will be
present in the coronary grooves. If the bird is emaciated, this fat may be absent or
have undergone serous atrophy, resulting in a gelatinous, wet appearance. Look for
any external lesions on the epicardial surface of the heart or on the surrounding fat



View of the left side of the heart



View of the apex of the heart



The bottom 1/3 of the apex of the heart has been removed. This view allows the
thickness of the ventricular walls and septum to be assessed. The right ventricular free
wall should be approximately 1/3 to 1/2 the thickness of the intraventricular septum
and the left ventricular free wall. In the normal heart, the lumina of the ventricles
should be small and there should be negligible space between the walls of the
ventriculae and the septum. In cardiac diseases, such as pulmonary hypertension or
congenital defects, this space will be widened



In this view, the chambers of the right atrium and ventricle have been opened by
making a cut up the right ventricular free wall. Once opened, the right atrioventricular
valve and endocardium are exposed. The septal leaf of the right valve is normally very
muscular



In this view, the chambers of the left atrium and ventricle have been opened by making
a cut up the left ventricular free wall. The left atrioventricular valve is normally thin and
smooth



The aorta has been opened by inserting scissors under the left atrioventricular valve
and cutting upward. The normal lumen of the aorta, as seen here, is creamy white and
the leaflets of the aortic valve are uniform and very thin



The liver is separated into a right and left lobe, as seen here, attached at the base. The
right hepatic lobe is slightly larger than the left and the liver margins should come to a
thin crisp edge



In domestic birds, the left lobe has a fissure running along its surface, dividing it into 2
parts



The overall size of the liver is variable, often extending beyond the edge of the
sternum. To identify hepatomegaly, look at the liver margins. Blunted or thickened
margins are a sign of an enlarged liver



Healthy hepatic parenchyma should be somewhat firm on palpation and have a smooth
and glistening appearance. The color of the liver can vary depending on the nutritional
state of the bird. Generally, the liver is reddish-brown but it can be light brown or even
slightly yellow, depending on the fat content in the diet. However, a very yellow liver is
an abnormal finding, except in chicks between 1 to 5 days of age



The gallbladder is located on the visceral surface of the right hepatic lobe. It is
normally dark green in color, due to the bile located within the lumen of this thin-walled
structure. During autolysis, bile pigments may leak out of the gallbladder, staining the
adjacent hepatic tissues yellow to green. This bile inbibition is a normal part of
autolysis and should not be confused with a lesion. Similar staining can also occur in
the ascending duodenum, adjacent to the area where the bile and pancreatic ducts
empty. The size of the gallbladder is variable and may be enlarged in birds that are off-
feed



View of the liver on cross section. As seen here, the color and texture should be
uniform. Focal or regional changes may indicate a lesion. Itâ€™s normal for a small
amount of blood to ooze from the cut surface of the liver
__________________



The lungs are tightly adhered to the dorsal rib cage. Their color should be bright pink in a fresh
bird but will become increasinly more congested, wet, and dark red with autolysis, as seen
here. To assess the lungs, do not over-interpret their color but rather, use a combination of
visual inspection and palpation to assess the health of this tissue



The air sacs are thin membranes distributed throughout the body. In a fresh healthy bird, air
sacs should be transparent but, as seen here, the membranes will become slightly cloudy after
death. In over-conditioned birds, fat may be present on the air sac membranes. Inflammation of
the air sacs can result in thickened membranes, opacities, or fibrin deposition. Fluid, foam, or
exudate can accumulate between the air sac membranes



The proventriculus is the glandular stomach that lies between the esophagus and the gizzard.
It is lined with mucosal glands that secrete digestive enzymes important in food break down.
On close inspection, these glands can be seen through the serosal surface, giving it a
â€œhoneycomb-likeâ€� texture. On palpation the proventriculus should feel turgid and, its
surface should be shiny tan. Look for abnormalities such as hemorrhagic lesions or neoplastic
infiltrates on its surface



The serosa of the proventriculus is normally shiny, tan, and has a fine vascular pattern. In a
fresh bird, on close inspection, the glands can be visualized through the mucosa. The
muscular wall of the proventriculus should feel uniformly turgid. Flaccidity or dilatation of the
organ might indicate an improper diet or feeding program, infection, or neuromuscular
dysfunction. The external features of the ventriculus, or gizzard, should consist of alternating


bands of dark red and light red smooth muscles, forming a roughly circular shape. These
muscles may be covered by a thick layer of fat, as seen here. On palpation, the gizzard should
be extremely firm. Thinning or laxity in the muscles may indicate inflammation, an improper
diet or feeding program, or neuromuscular problems

The proventriculus in situ



The serosa of the proventriculus is normally shiny, tan, and has a fine vascular pattern. In a
fresh bird, on close inspection, the glands can be visualized through the mucosa. The
muscular wall of the proventriculus should feel uniformly turgid. Flaccidity or dilatation of the
organ might indicate an improper diet or feeding program, infection, or neuromuscular
dysfunction. The external features of the ventriculus, or gizzard, should consist of alternating
bands of dark red and light red smooth muscles, forming a roughly circular shape. These
muscles may be covered by a thick layer of fat. On palpation, the gizzard should be extremely
firm. Thinning or laxity in the muscles may indicate inflammation, an improper diet or feeding
program, or neuromuscular problems



View of the serosal surface of the proventriculus and gizzard



Close-up of the glands of the proventriculus as seen through the outer wall



View of the glands of the proventriculus as seen from the mucosal surface



Close-up view of the glands of the proventriculus as seen from the mucosal surface



The contents of the proventriculus can vary from mucoid and creamy to more formed pieces of
ingesta, depending on how recently the bird ate



View of the left side of the proventriculus and gizzard



The consistency of the gizzard contents will vary depending on the stage of digestion.
Generally, it contains fibers and portions of seeds. Additionally, small pebbles, ingested to
facilitate the break up of food, may also be present



The mucosa of the gizzard is covered by a sturdy layer of protein called koilin, which aids in
food digestion. The koilin layer should be smooth and uniform. The color may vary from white,
to yellow, to green depending on the diet and the degree of bile staining



Close-up view of the koilin layer of the gizzard



The spleen is located dorsal to the gizzard



On very close inspection, the spleen as a slight stippled pattern



View of the cut section of the spleen. On cross section, the spleen may appear slightly
granular due to the variations in red and white pulp



The duodenum has a descending and ascending loop, arranged in a U-shape. The
loops are held together by a thin strip of mesentery and surround the pancreas. The
appearance of the intestine can vary greatly depending on the post-mortem condition
of the bird. In a fresh bird, the serosa of a healthy intestine is usually pink, smooth, and
glistening. As the post-mortem interval increases, the intestinal walls will become
congested, as seen here, and eventually, even a healthy loop of bowel may appear dark
red. However, if the serosa has a dull granular appearance, this can be evidence of
inflammation. The normal appearance of the pancreas is pale red or slightly yellow. On
close inspection, its glandular nature is evident. Swelling of the pancreas can be
recognized if the organ extends beyond its normal location between the loops of the
duodenum



The walls of the duodenum should be smooth and uniform and offer little resistance to
incision. In the proximal duodenum, the ingesta is normally mucoid and pale tan to
yellow. Distal to the bile ducts, the ingesta becomes more green in color



The normal appearance of the pancreas is pale red or slightly yellow. On close
inspection, its glandular nature is evident. Swelling of the pancreas can be recognized
if the organ extends beyond its normal location between the loops of the duodenum



On close inspection, the pancreas has a fine glandular texture



After 10 days of age, the only remnant of the yolk sac is a small tag of scar tissue,
called Meckelâ€™s diverticulum. This tag, located on the antimesenteric side of the
intestine, contains lymphoid tissue and is part of the GALT, or Gut Associated
Lymphoid Tissue. Meckelâ€™s diverticulum is also an important anatomical landmark,
as it is located at the junction between the jejunum and the ileum. Being able to
differentiate the jejunum from the ileum is important to generating differentials for
intestinal diseases. Some infections, such as coccidiosis, have a predilection for the
jejunum and other diseases target the ileum



At the junction between the ileum and the descending colon, are two blind-ended sacs
known as the ceca. In domestic poultry, the cecae are large structures that bend over
themselves, with their apices pointing caudally. The walls should be thin and semi-
translucent, allowing the greenish-colored intestinal contents to be visualized within. If
the walls are opaque, thin or irregular, infection should be suspected



At the base of the ceca, near the junction of the ileum and the descending colon, are 2
important lymphoid structures called cecal tonsils. The tissue here bulges outward
slightly as it is thicker and slightly more granular



As demonstrated here, the cecal tonsils should be opened and the mucosa examined
closely. This is a common location for lesions to be detected. In inflammatory or
neoplastic diseases, the tonsils may be come enlarged and mottled red and tan. In
some viral infections, the lymphoid tissue may become necrotic, causing the tonsils to
become red



The cecal tonsil has been opened to show the mucosa. Itâ€™s important to examine
this area closely for lesions. In inflammatory or neoplastic disease, the cecal tonsils
may become enlarged and mottled red and tan. In some viral infections, this lymphoid
tissue may become necrotic, causing the tonsils to become red



The serosa of the ileum should be shiny, tan, and smooth, with no thickening or
bulges. Be careful not to over-interpret the color of the intestinal walls as post-mortem
congestion and autolysis can quickly turn the intestinal walls red or black. Because the
intestinal walls are semi-translucent, look for areas of proliferation or mucosal exudate
which can sometimes be visualized through the intestinal wall. At the junction between
the ileum and the descending colon, are two blind-ended sacs known as the ceca. In
domestic poultry, the cecae are large structures that bend over themselves, with their
apices pointing caudally. The walls should be thin and semi-translucent, allowing the
greenish-colored intestinal contents to be visualized within. If the walls are opaque,
thin or irregular, infection should be suspected



The quality of intestinal ingesta can yield important clues about the functional status of
the intestines. If the ingesta is normal, as seen here, regardless of the appearance of
the intestinal wall, the intestines were likely functioning normal at the time of death. If
the content is abnormal, intestinal dysfunction is present. Keep in mind that as the
ingesta moves though the intestines, its color and consistency will change. In the
jejunum, pictured here, the ingesta becomes slightly thicker and yellow tan in color



Distal to the ceca, the intestines continue as a short straight tube known as the
descending colon. These walls should be smooth and uniform. Look for any dilatations
which may indicate an obstruction due to a mechanical blockage, a scar, or another
disease process



The cloaca is the common chamber for the gastrointestinal, urinary, and reproductive
tracts. Here the cloaca has been opened. By the time ingesta enters the cloaca, it
should have the normal color and consistency of feces and will be mixed with urates
from the urinary system

__________________



On the dorsal wall of the cloaca is a diverticulum called the Bursa of Fabricius. This structure
is an important lymphoid organ. The shape of the bursa varies with species. In the chicken, it
is roughly pear shaped. In ducks, geese and turkeys it is more spindle shaped. The size varies
with the age of the bird. It typically reaches its maximum size between 4 to 12 weeks of age, at
which time it can weigh up to 4 grams. Normally, the bursa begins to involute when the bird is
approximately 3 months of age. By the time the bird reaches sexual maturity, it may no longer
be evident on gross examination



The bursa of Fabricius has been opened to show its mucosal surface. The normal mucosa
consists of many folds of tissue, which are pale white to pink or tan and slightly firm on
palpation



The vent, located just beneath the tail, is the external orifice of the urinary, genital and
gastrointestinal systems. The normal vent is free of fecal and urate staining, swelling, redness,
or evidence of trauma



This image shows the normal ovary of a sexually immature female, approximately 10 weeks of
age. Here, the ovary is small and inactive



View of the dorsal aspect of the ribs. Note that the ventral ribs have been removed from the
field



The kidneys consist of a right and left chain, with each chain being made up of 3 lobes. The
lobes are tightly embedded in the bone of the synsacrum. They are normally red to dark
mahogany brown in color and have a slightly granular texture



This image shows a detailed view of the normal texture of the kidneys



The nerves should have a creamy-white color and a slightly striated texture on close
inspection. This image shows a normal ishiadic plexus in the caudal coelomic cavity



The thyroid glands should be smooth, oval, and reddish-brown in color. On very close
inspection, the thyroid glands have a very fine granular appearance



A properly formed beak, shown here, is bilaterally symmetrical and the upper and lower halves
should form a smooth line where they articulate



A properly formed beak is bilaterally symmetrical and the upper and lower halves should form
a smooth line where they articulate. Nutritional imbalances may result in beak malformations.
The color of the beak depends on the birdâ€™s coloration, with lighter birds typically having
yellow beaks. However, beak color can also be influenced by physiologic factors. For example,
yellow pigment in the beak may be lost as the chicken produces more eggs



The oropharynx should be examined for any lesions. Note that birds do not have a soft palate
or a discrete boundary between the oral cavity and the pharynx. The color of the oral mucosa
will vary with lighter birds tending to have a pink mucosa while darker birds will have more
pigment. Look for ulcers, erosions, opacities, diptheritic nodules, or other lesions



A birdâ€™s tongue is supported by the hyobranchial apparatus, making it somewhat inflexible



The color of the oral mucosa will vary with the overall coloration of the bird. However, the
mucosa should be free of ulcers, erosions, opacities, diptheritic nodules, and other lesions



The dorsal surface of the chicken tongue should be smooth and pink. There is a row of large
papillae near the caudal attachment of the tongue. Inspect the tongue for any lesions such as
ulcers or nodules



The dorsal surface of the chickenâ€™s tongue is smooth and there is a row of large papillae
near the caudal attachment. When inspecting the tongue, look for ulcers and erosions



On the roof of the oropharynx is a fissure, called the choana, which opens into the nasal
cavity. Inspect the area around the choana for ulcers. The choana is also a good place to find
respiratory exudate. Birds do not form liquid pus and inspusated exudate tends to accumulate
in the choanal orifice. If exudate is present, you can collect a swab sample from the choana.
The choana is surrounded by ridges and rows of sharp well-demarcated papillae that point
caudally. A variety of diseases can damage the papillae, resulting in blunting



Just caudal to the choana is the infundibular cleft. This is the opening to the Eustachian tube
and it is surrounded by ridges and rows of sharp well-demarcated papilla that point caudally



The tongue, esophagus, and trachea have been removed as one unit. This view allows the
structures of the structures of the caudal oral cavity and pharynx to be examined more closely



The tongue, esophagus, and trachea have been removed as one unit. This view allows the
structures of the caudal oral cavity and pharynx to be examined more closely


Zagazig University Avian Necropsy Guide

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Zagazig University Avian Necropsy Guide