Clinical Description

This impression smear, made from the exudate of infected tissues, shows intracytoplasmic inclusions associated with Chlamydophila psittaci infection.

Clinical Description

This impression smear, made from the exudate of infected tissues, shows intracytoplasmic inclusions associated with Chlamydophila psittaci infection.

Clinical Description

This impression smear, made from the exudate of infected tissues, shows intracytoplasmic inclusions associated with Chlamydophila psittaci infection.

Clinical Description

This impression smear, made from the exudate of infected tissues, shows intracytoplasmic inclusions associated with Chlamydophila psittaci infection.

Clinical Description

This impression smear, made from the exudate of infected tissues, shows intracytoplasmic inclusions associated with Chlamydophila psittaci infection.

Morphologic Diagnosis

Air sac: Acute fibrinous air sacculitis

Clinical Description

In Chlamydiosis, airsacculitis is one of the most common post-mortem findings. Here, the abdominal air sacs are thickened and coated with fibrin. Foamy white exudate may also be present in the lumen of the air sacs.

Pathologic Description

The air sac is thickened and covered with a thin film of fibrinous friable material. The lumen of the air sac contains a small amount of foam.

Clinical Description

The clinical signs of Chlamydophila psittaci are variable and depend on the host species, age, and strain of Chlamydia. This turkey is showing lethargy and weakness. Other general signs may include fever, drop in feed consumption, and drop in egg production.

Morphologic Diagnosis

Liver: Moderate acute fibrinous perihepatitis.

Clinical Description

In Chlamydophila psittaci, the liver is often enlarged and covered with fibrin. Severe perihepatitis is a common post-mortem finding in Chlamydiosis.

Pathologic Description

The liver is covered by a thin, opaque film of white, loosely adherent, friable material.

Clinical Description

Chlamydophila psittaci can infect many species of both domestic and wild birds. The disease may be debilitating in parrots and other psittacine cage-birds, as seen here. It was originally called “parrot fever” because it was first recognized in psittacine birds.

Morphologic Diagnosis

Conjunctiva: Mild acute conjunctivitis.

Clinical Description

Pigeons, ducks, and geese may exhibit unilateral or bilateral conjunctivitis, as seen here. Sometimes this conjunctivitis may be associated with a purulent oculo-nasal discharge.

Pathologic Description

The conjunctiva is slightly swollen, red and glistening.

Morphologic Diagnosis

Liver: Severe hepatomegaly and congestion.

Clinical Description

In Chlamydophila psittaci, the liver may be enlarged, discolored, and congested, as seen on the liver on the left. A normal liver is shown on the right for comparison.

Pathologic Description

Livers from two different birds are represented in this picture. The liver on the right is normal. The liver on the left is markedly enlarged, has blunted edges, and is dark red.

Morphologic Diagnosis

Liver: Multifocal necrosis.
Liver: Severe lipidosis.

Clinical Description

This is a cut surface of liver showing white multifocal areas of necrosis in the liver parenchyma caused by C. psittaci infection.

Pathologic Description

A section of bright yellow liver has been incised. On the cut surface there are numerous, small, well-demarcated soft, white foci scattered throughout the parenchyma.

Morphologic Diagnosis

Liver: Moderate acute multifocal necrosis

Clinical Description

In Chlamydophila psittaci, the liver may have white necrotic foci scattered throughout the organ.

Pathologic Description

The surface of the liver is stippled by numerous, small, irregularly shaped, well-demarcated white foci. On incision, these foci are slightly soft and sunken.

Morphologic Diagnosis

Pericardium: Severe acute diffuse fibrinous pericarditis.
Liver: Moderate hepatomegaly and congestion.

Clinical Description

In this photo, fibrinous pericarditis and an enlarged congested liver are caused by Chlamydophila psittaci infection. Avian chlamydiosis frequently causes systemic disease and it is an important rule-out for other common bacterial causes of systemic infections, such as the ones produced by Escherichia coli and Riemerella anatipestifer.

Pathologic Description

The pericardium is markedly thickened by layers of pale tan to white, adherent, fibrillar, friable material. The liver is enlarged with blunt edges and ill-defined regions of the parenchyma are dark red.

Morphologic Diagnosis

Pericardium: Severe acute diffuse fibrinous pericarditis.

Clinical Description

In Chlamydophila psittaci, the heart may be enlarged (due to myocarditis) and the epicardial surface may be covered with fibrin plaques, as seen here.

Pathologic Description

The pericardium is thickened and covered by a large about of pale tan or white, soft, adherent, fibrillar material. The surface of this tissue is slightly irregular and glistening.

Morphologic Diagnosis

Heart: Moderate acute diffuse fibrinous pericarditis and epicarditis.

Clinical Description

In Chlamydophila psittaci, the pericardium may be congested, thickened, and may have fibrinous exudate on its surface. Here, the pericardium has been opened, revealing the epicardial surface of the heart, also covered in fibrin.

Pathologic Description

The pericardium has been opened to reveal the epicardial surface of the apex of the heart. The pericardium is thick, opaque and covered by a slightly granular, friable material. The epicardium is covered by a thin layer of opaque, fibrillar, white material.

Morphologic Diagnosis

Heart: Severe chronic caseous pericarditis and epicarditis.

Clinical Description

In this photo, depicting a Chlamydophila psittaci infection, the pericardial membrane of the turkey is thickened and covered with fibrinous exudate. The pericardium has been opened, revealing dried yellow exudate adhered to the epicardium. This infection often causes systemic disease and it is an important rule-out for other common bacterial causes of pericarditis, such as the ones produced by Escherichia coli and Riemerella anatipestifer.

Pathologic Description

The abnormal pericardium has been opened to reveal the abnormal epicardial surface of the heart. The pericardium is markedly thickened by thick, firm, glistening tissue and the pericardial space contains chunks of thick, yellow soft material. This material adheres to the epicardium, which is thick, opaque and covered by sheets of adherent friable material.

Clinical Description

As shown here, in certain virulent strains of Chlamydophila psittaci, the lungs may be congested and fibrinous exudate may be present in the pleural cavity.

Morphologic Diagnosis

Spleen: Moderate to marked necrosis and congestion

Clinical Description

In Chlamydophila psittaci, lesions affecting the spleen may include enlargement and changes in color, as seen here.

Pathologic Description

The spleens from three animals are represented here. Each is enlarged and rounded. The spleen on the far left is mottled red and tan. The spleen in the middle has an extensive area which is paler than normal adjacent to a dark, red, wet area. The spleen on the right is diffusely dark red, wet and swollen.

Morphologic Diagnosis

Liver and spleen (left of photo): Hepato and splenomegaly with congestion
Liver (right of photo): Bile stasis
Spleen (right of photo): Splenomegaly

Clinical Description

Enlargement and congestion of the liver and spleen, collected from chicken embryos inoculated with Chlamydophila psittaci. A normal liver and spleen are shown in the middle of the photo.

Pathologic Description

The liver and spleen from three separate embryos are represented in this picture. The middle set of tissue is normal. The tissues on the right and left are from embryos experimentally inoculated with Chlamydophila psittaci. The liver and spleen on the left are enlarged and dark red. The liver on the left is dark green and the spleen is slightly enlarged and red.

Morphologic Diagnosis

Liver and spleen (right): Hepato and splenomegaly
Spleen (left): Splenomegaly

Clinical Description

Enlarged, mottled, and congested liver and spleen collected from chicken embryos inoculated with C. psittaci. A normal liver and spleen are shown in the middle.

Pathologic Description

The livers and spleens from three embryos are depicted. The liver and the spleen in the center of the photo are normal. The other two sets of tissue are from embryos experimentally inoculated with C. psittaci. The liver and spleen on the right are enlarged. The spleen on the left is enlarged. Note: The mottled colors of the embryonic liver are often normal due to accumulation of lipid in the hepatocytes and areas of extramedullary hematopoiesis. Distinguishing these normal developmental changes from pathologic processes requires histopathology.

Clinical Description

In some cases, Chlamydophila psittaci can be associated with the presence of abundant fibrinous exudate on the serosal surfaces of the viscera throughout the coelomic cavity.

Morphologic Diagnosis

Embryo: Congestion

Clinical Description

Fertile chicken eggs inoculated with Chlamydophila psittaci may show embryo mortality 3-10 days after inoculation. Vascular congestion, seen in the bottom embryo, should be verified in the embryos that have died. A normal non-inoculated embryo is shown on the top for comparison.

Pathologic Description

Two chicken embryos are present in this photo. The top embryo is normal. The bottom embryo is from an egg inoculated with C. psittaci. The tissues of the bottom embryo are reddened.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

View of the left side of the heart.

Clinical Description

View of the apex of the heart.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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. It’s normal for a small amount of blood to ooze from the cut surface of the liver.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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 “honeycomb-like” 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.

Clinical Description

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.

Clinical Description

The proventriculus in situ.

Clinical Description

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.

Clinical Description

View of the serosal surface of the proventriculus and gizzard (ventriculus).

Clinical Description

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

Clinical Description

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

Clinical Description

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

Clinical Description

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

Clinical Description

View of the serosal surface of the proventriculus and gizzard (ventriculus).

Clinical Description

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.

Clinical Description

View of the left side of the proventriculus and gizzard.

Clinical Description

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.

Clinical Description

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.

Clinical Description

Close-up view of the koilin layer of the gizzard (ventriculus).

Clinical Description

The spleen is located dorsal to the gizzard.

Clinical Description

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

Clinical Description

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

Clinical Description

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

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

On close inspection, the pancreas has a fine glandular texture.

Clinical Description

After 10 days of age, the only remnant of the yolk sac is a small tag of scar tissue, called Meckel’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. Meckel’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.

Clinical Description

After 10 days of age, the only remnant of the yolk sac is a small tag of scar tissue, called Meckel’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. Meckel’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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

The cecal tonsil has been opened to show the mucosa. It’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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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

Clinical Description

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

Clinical Description

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.

Clinical Description

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

Clinical Description

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.

Clinical Description

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.

Clinical Description

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

Clinical Description

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 bird’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.

Clinical Description

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.

Clinical Description

A bird’s tongue is supported by the hyobranchial apparatus, making it somewhat inflexible.

Clinical Description

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.

Clinical Description

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.

Clinical Description

The dorsal surface of the chicken’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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

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.

Clinical Description

The esophagus runs down the length of the neck and, in domestic species, is interrupted by a diverticulum called the crop. The esophagus continues down the neck and empties into the proventriculus. The esophagus and crop are thin-walled and located just below the skin. Their outer surfaces should be pale tan and smooth.

Clinical Description

The esophagus runs down the length of the neck and, in domestic species, is interrupted by a diverticulum called the crop. The esophagus continues down the neck and empties into the proventriculus. The esophagus and crop are thin-walled and located just below the skin. Their outer surfaces should be pale tan and smooth.

Clinical Description

The mucosal surface of the esophagus should be smooth and glistening. The cranial portion contains many glands and the caudal portion has numerous longitudinal folds. The color along the entire length should be pale tan to pink. The presence of proliferative lesions may indicate a viral infection or a dietary imbalance.  You can gently wash away any food material from the walls of the crop with some water but do not scrape the mucosa. Food material should wash away easily while fibrin and exudate will stick to the mucosa. Look for ulcers and erosions, which appear as red or pale depressions in the mucosa.

Clinical Description

The caudal portion of the normal esophagus has numerous longitudinal folds, as seen here.

Clinical Description

You can gently wash away any food material from the walls of the crop with some water but do not scrape the mucosa. Food material should wash away easily while fibrin and exudate will stick to the mucosa. Look for ulcers and erosions, which appear as red or pale depressions in the mucosa.

Clinical Description

You can gently wash away any food material from the walls of the crop with some water but do not scrape the mucosa. Food material should wash away easily while fibrin and exudate will stick to the mucosa. Look for ulcers and erosions, which appear as red or pale depressions in the mucosa.

Clinical Description

The trachea should be uniform in color, ranging from pale pink to tan or white and the external surface should be smooth. Upper respiratory disease may produce tracheal lesions that are sometimes visible on the outer surface. Look for discoloration, nodules, or irregularities in the tracheal cartilages.

Clinical Description

The trachea is a thin tube completely encircled by small cartilagenous rings. The trachea should be uniform in color, ranging from pale tan to white and the external surface should be smooth. Look for discoloration, nodules, or irregularities in the tracheal cartilages.

Clinical Description

The trachea is a thin tube completely encircled by cartilagenous rings. The trachea should be uniform in color, ranging from pale pink to tan or white and the external surface should be smooth. Upper respiratory disease may produce tracheal lesions that are sometimes visible on the outer surface. Look for discoloration, nodules, or irregularities in the tracheal cartilages.

Clinical Description

At the terminal end of the trachea lies the syrinx, a flattened area at the junction of the trachea and the primary bronchi. The syrinx is responsible for generating vocal sounds.

Clinical Description

Since the diameter of the syrinx is significantly smaller than that of the trachea, examine this area closely for occlusions caused by exudate, fungal mats, or parasites.

Clinical Description

Since the diameter of the syrinx is significantly smaller than that of the trachea, examine this area closely for occlusions caused by exudate, fungal mats, or parasites.

Clinical Description

View of the inside lumen of the trachea.

Clinical Description

The left jugular vein of the bird, seen here, is much larger than the right.

Clinical Description

The left jugular vein of the bird, seen here, is much larger than the left. The vagal and glossopharyngeal nerves are closely associated with the veins.

Clinical Description

The vagal and glossopharyngeal nerves run parallel with the jugular veins.

Clinical Description

The thyroid glands are located on each side of the neck, medial to the jugular vein and cranial to the origin of the subclavian and common carotid arteries.

Clinical Description

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

Clinical Description

Just caudal to the thyroid glands are the small pale pink parathyroid glands. The right parathyroid gland, seen here, lies directly adjacent to the right thyroid gland. The left parathyroid gland is slightly separated from the left thyroid gland.

Clinical Description

The thymus is a bilateral chain of structures, located in the lateral neck region. each side is composed of 4 to 7 lobes. In chickens less than 17 weeks of age, the thymus should be visible but normally regresses around the time of sexual maturity.

Clinical Description

The lobes of the thymus, normally present only in immature birds, are pale tan to pink in color.

Clinical Description

The avian brain has a smooth surface, with no gyri or sulci. Its cortex should appear smooth and glistening and the right and left sides should be symmetrical.

Clinical Description

This image shows a detailed view of the surface of the normal cerebrum.

Clinical Description

The 3 muscles involved in flight in the bird, called the pectoral muscles, lie on either side of the keel bone. These muscles are very large, making them ideal for body muscle assessment. The muscles should be smooth and have a relatively uniform texture.

Clinical Description

The pectoral muscles can be removed from the keel and ribs in order to examine them more closely. Look for areas of necrosis, inflammation, or hemorrhage.

Clinical Description

With the muscles removed, look for areas of necrosis, inflammation, or hemorrhage. A series of parallel cuts through the muscle bellies can facilitate this assessment.

Clinical Description

The eyelids should be free of swelling or exudate from ocular discharge.

Clinical Description

The eyelids should be free of swelling or exudate from ocular discharge.

Clinical Description

The cornea should be clear and convex and the sclera white. Iris color will vary with the breed and color of the bird however, look for abnormalities of the iris such as redness, anterior synechia, or exudate in the anterior chamber. The shape of the iris and pupil should be uniform and round.

Clinical Description

The conjunctiva is a mucous membrane. It should be light pink in color and free of any redness, swelling, or exudate.

Clinical Description

The eye has been removed from the skull showing the full extent of the orbit.

Clinical Description

The ears in the bird are simple ostea, with no external pinna. The openings should be free of swelling, exudate, or other material.

Clinical Description

The comb and wattles are outgrowths of skin that are highly vascularized, making them a useful way to assess the bird's overall health. They are normally bright red but their color will quickly fade after death. However, they should remain firm and uniform on palpation. look for abnormalities such as edema, petechiae, necrosis, cyanosis, papules and ulcers.

Clinical Description

The infraorbital sinuses are triangular-shaped cavities, located rostroventral to the eyes. The sinuses are air-filled lumens, with one opening into the nasal cavity and the other into the caudal nasal cavity.

Clinical Description

As seen here, the legs bones of the should be straight and symmetrical.

Clinical Description

The leg bones should be straight and symmetrical. Palpate the bones for fractures and calluses and the joints for swelling or effusion. Flex and extend all the joints to assess range of motion, keeping in mind the effects of rigor mortis.

Clinical Description

The skin on the limbs is covered by scales that are normally dry, flat, and slightly overlapping. Some parasites live beneath the scales of the legs. Some infectious diseases can cause keratinous outgrowths from this skin.

Clinical Description

The skin on the limbs is covered by scales that are normally dry, flat, and slightly overlapping. Some parasites live beneath the scales of the legs. Some infectious diseases can cause keratinous outgrowths from this skin.

Clinical Description

Digital pads cover the plantar surface of the birds’ feet. These pads are composed of thick skin and adipose tissue. In the center of the foot, there is a large central metatarsal pad. The pads should be soft, free of scabs, swellings, edema, hemorrhages, or other lesions.

Clinical Description

In the center of the foot, there is a large central metatarsal pad. The pads should be soft, free of scabs, swellings, edema, hemorrhages, or other lesions.

Clinical Description

In birds housed on the floor, claws will normally come to a blunt tapered end, as seen here. Claws may be somewhat sharper in birds housed in cages. Curling or fraying claws are abnormal findings.

Clinical Description

Birds have several types of feathers distributed across various regions of their body including down, body feathers, and flight feathers. Look for abnormalities in feather conformation such as warping or malformed barbs and barbules.  Make note of any body regions that are missing feathers. Feathers are normally distributed along tracks on the body, called pterylae. These tracks are interspersed with featherless tracts called apteria. Keep in mind, that not all feather loss is abnormal. Seasonal feather molting is a normal physiologic process. Additionally, females who are incubating eggs may have an area on their abdomen lacking feathers, called the brood patch. In non-pathologic feather loss, the skin will appear healthy. In cases of pathologic feather loss, such as excessive feather picking by the bird, or its cage mates, the skin will be traumatized.

Clinical Description

This image shows a typical “down” feather.

Clinical Description

The skin in the chicken is normally very thin and the amount of pigment varies from pink to black, depending on the coloration of the bird. The skin should be free of exudate and have little or no scale. Look for any lesions or evidence of ectoparasites.

Clinical Description

Feathers are normally distributed along tracks on the body, known as pterylae, seen here. These tracks are interspersed with featherless areas called apteria. Patches of feather loss may be due to normal physiologic processes, such as seasonal molting. Pathologic feather loss can result from trauma and infection and is associated with skin lesions.

Clinical Description

Pay attention to the feather sheath, the area where the feather emerges from the follicle. Swelling in this location can be indicative of several types of infection.

Clinical Description

Pay attention to the feather sheath, the area where the feather emerges from the follicle. Swelling in this location can be indicative of several types of infection.

Clinical Description

The uropygial, or preen gland, is located dorsal to the base of the tail. This cutaneous gland secretes an oily substance that birds spread over their feathers during preening. These secretions help maintain normal healthy feathers.

Clinical Description

The body of the gland is located subcutaneously and its two lobes can sometimes be visualized beneath the skin, as seen here. The gland’s duct exits externally through a small papilla. Infected glands may result in swelling and reddening of the surrounding skin.

Clinical Description

Cartilage should be smooth, shiny, and white with a slightly blue tinge, as seen here. Look for degenerative changes and roughed, discolored areas.

Clinical Description

In a young bird, cut the long bone of the leg lengthwise to examine the epiphysis. Nutrient or mineral deficiencies can lead to poor mineralization of the bone. Look for widening of the epiphyseal plate or generalized hypoplasia of the bone.