Health & Management / Disease Investigation & Management / List of hyperlinked Techniques & Protocols:

Necropsy of Birds

(See also Necropsy of Mammals (Techniques Overview) )

Click links below for Video: Bird Necropsy Protocol for West Nile Virus Surveillance Video Available: Bird Necropsy Protocol for West Nile Virus Surveillance:
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Click image for full page view with caption Click image for full page view with caption Swabbing unhatched egg for culture. Click here for full-page view with caption. Foreign bodies in gizzard. Click here for full-page view with caption.

Introduction and General Information

Post mortem examination (i.e. necropsy) is an extremely valuable tool in disease investigation and management. It is important to approach each carcass with an open mind, not assuming that the cause of death is known, even if there are obvious external lesions or a known on-going disease problem.
  • N.B. Examination of embryos and dead-in-shell chicks may be useful as well as examination of adult animals.

In performing a necropsy or post mortem examination, it is important to:

  • have a systematic approach, whether head-to-tail, system by system (digestive system, respiratory system etc.) or any other.
  • recognize the normal anatomy, normal appearance of organs/tissues and anatomical variation between species.
  • accurately describe lesions/abnormalities.
  • keep accurate records, including a unique identifying number for each carcass and samples from that carcass.
  • avoid the use of non-standard abbreviations in permanent records.
  • preserve samples (tissues, parasites etc.) for future reference/research

Suitable dissection instruments, cutting board, scales (both gram and kilogram), sterile culture swabs, needles and syringes, clean slides for impression smears, appropriate sterile containers (e.g. petri dishes, plastic bags in which tissues can be frozen), fixation medium (buffered formalin, also 70% alcohol) should be available, also photography equipment for visual recording of findings.

  • For small birds, use magnifying spectacles or a dissecting microscope .
  • N.B. In the event of a die-off it is important to examine a number of individuals, representative for the range of species affected, and to remember that more than one disease process may be acting at any one time and that the major cause(s) of death may change during a prolonged die-off.
  • The results of the post mortem examination should be used in conjunction with the history of the bird or birds and assessment of the environment. (See History and Documentation - General and Environmental Assessment - General)
  • Photographs should be taken with equipment which can provide sharp focus and maximum depth of field (a macro lens and fast shutter speed, together with high speed film/seson are recommended); a scale should be included, whether e.g. a ruler/tape measure or a recognisable object such as a coin.
  • Notes should be completed during, not after the necropsy, preferably by dictating (into a voice-activated recorder or to an assistant).
  • Record if an organ or body system has not been examined (e.g. write "NE" on the necropsy form). due to damage or decomposition.
  • NOTE: If foreign bodies such as bullets or lead pellets are found and there is the possibility of legal proceedings, these should, in the presence of a witness be collected, labelled (including the initials of the label) and stored in a safe place.

(B11.11.w20, B15, B36.2.w2, B36.3.w3, B64.App14.w10, D440, P4.1988.w1)

Waterfowl Consideration
  • Knowledge of normal anatomy is useful e.g. long coiled trachea in some swan species and long tracheal loop sub-cutaneous over sternum of Anseranas semipalmata - Magpie goose.
Crane Consideration
Published Guidelines linked in Wildpro

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General Examination

  • Record the age and sex (if known), any identifying number, bands, tags etc.
    • Retain any rings, microchips etc.
  • Examine the inside of the container/wrappings the carcass has been presented in, noting contaminants (e.g. mud, oil) and possible external parasites such as leeches, lice or mites which may have left the host.
    • Collect extoparasites (all, or a large, representative sample) and place in a bottle of 7-% ethyl alcohol. Seal the bottle and label it immediately using pencil/waterproof pen, preferably twice: once on a piece of card placed inside the container and once on the outside of the containiner (NOT on the lid).
  • Weigh the carcass.
  • Measure the wing, beak and tail length and any other measurements if suggested/requested by a zoologist.

(J34.14.w1, B11.11.w20, B13.14.w19, B14, B15, B36.2.w2, P18.w1)

Waterfowl Considerations --
Crane Consideration
Associated techniques linked from Wildpro Click for Video: Bird Necropsy Protocol for West Nile Virus Surveillance Video Available: Bird Necropsy Protocol for West Nile Virus Surveillance:
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General external examination

Before opening the bird's carcass, examine the external surface of the carcass. Note whether the carcass is fresh or decomposed and whether it has been frozen, also whether it is intact or scavenged, and if scavenged to what degree. Permanent written records should indicate the following:
  • General appearance of carcass and plumage - e.g. wet, muddy, oiled, clean, bloody, covered in salt; feathers intact, damaged or missing. If contaminated, note extent and areas affected.
  • Presence of parasites - leeches (particularly around eyes and nares), lice, ticks etc.
  • Body condition - prominence of keel, whether the crop (if any is full).
  • Check body orifices for discharges, ulceration, plaques, growths and foreign bodies.
  • Radiography may be indicated to detect e.g. fractures, radiodense foreign bodies (particularly lead shot in the gizzard, evidence of shooting, fishhooks), metabolic bone disease.
    • Whole-body radiography may be useful for small birds to detect minor fractures, gunshot wounds, lead pellets in the gizzard.
  • Preparing for internal examination: Wet feathers thoroughly with soapy water or disinfectant in water to minimize feather debris.
  • N.B. tissue samples, swabs for culture and impression smears should be taken as tissues are examined and before they become contaminated. Tissue to be fixed should be no more than 3-5mm thick, and thinner if congested, although whole lung may be fixed.

(B13.14.w19, B64.App14.w10, B36.2.w2 - full text included, D440, P4.1988.w1)

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Head and neck

  • Note any obvious injuries (bruising, lacerations, puctures, burns etc.) to the head, eyes or beak/bill.
  • Check the bill/beak carefully for any deformities, overgrowth, scales or crusting
    • Note: it is important to know the normal appearance of the beak in the species being examined.
    • In e.g. gannets it is normal for the external nares to NOT be present.
  • Check inside the mouth, including on and under the tongue, for any ulcers, plaques, growths, foreign bodies or burns.
  • Raise the ear coverts and examine the external aural canal. See: Lacerations & Punctures, including bite wounds
  • For thorough examination of the head, cut through the sinuses, cut through the corner of the bill and examine the hard palate and the tongue.
  • Note any scabs or masses around the eyes as seen with Avian Pox
  • Examine the eyes; if the carcass is very fresh, useful information may be gained by examining the eyes using indirect ophthalmoscopy. (D440)
  • Remove the eyes carefully by dissecting with scissors and forceps.
    • Fix in a preservative preferred by the histopathologist, e.g. Bouin's or Zenkers solution.
  • Cut the skin over the head and peel this back, noting any bruising.
    • Since there may be agonal bleeding in the skull, this should be considered of pathological significance only if there are also contusions and/or haemorrhages in the overlying skin and/or intracranially. (D440)
(B13.14.w19, B64.App14.w10, D440, P4.1988.w10K, V.w5)
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Skin and Feathers 

The condition of the skin and feathers, and the presence of any external parasites, should be noted.
  • Feather condition should be noted before wetting the carcass to reduce feather debris, since the state of the feathers may be relevant to the diagnosis.
  • Check feather colour, note any fret marks, broken feathers, loss or deformity of feathers.
  • If feather contaminants (e.g. oil) are suspected, sample feathers should be removed at this time and placed in appropriate storage containers.
  • Examine the uropygeal (preen) gland (over the last vertebra, at the base of the tail.
    • Not present in Struthionidae, Rheidae, Casuariidae, Otididae (bustands), and may be absent or small in some Caprimulgidae, Columbiformes, Psittaciformes and Piciformes.
    • Very well developed in Spheniscidae, Podicipedidae (Grebes), Procellariidea, Laridae (gulls)
  • Look for brood/incubation patches: thickened, highly vascular areas of featherless skin (one median or two lateral patches) in females and/or males depending on species (these do not form in all species).
  • Check the skin of the legs for scaling or crusting which may be due to bacterial, viral, fungal or parasitic infection.
  • Scabs and swellings may develop with viral infection, bacterial infection or neoplastic lesions.
  • Sections of skin should be stored in formalin.
  • Any ectoparasites found (e.g. mites) should be examined microscopically for identification, and stored.

(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)

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Musculoskeletal system 

  • Examine the wings and the legs for any obvious abnormalities - fractures, bruises, grazed or broken skin, open wounds, swellings.
    • Determine whether any swelling is hard (bony), soft or fluctuant.
  • Incise over major limb joints (knee, hock, shoulder, examine the state of the synovial fluid, joint surfaces and tendon sheaths.
    • If appropriate, take swabs of synovial fluid for bacteriological examination.
  • Incise the leg and (later, once the carcase is being opened) breast muscles
    • Note colour (e.g. general pallor or pale areas), any haemorrhage, penetrating wounds, general mass (normal or reduced).
  • Check whether the leg bones may be bent or easily broken.
  • Check the feet, particularly the plantar surfaces. In web-footed birds note the state of the webs.
  • Skinning or partial skinning is needed to examine the muscles fully.
  • Sections of muscle and femur should be stored in formalin.

(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)

Waterfowl Consideration --
Crane Consideration Examine carefully for entangling foreign bodies (e.g. monofilament line), fractures, enlarged joints, joint luxations, limb deformities

Note: Developmental limb deformities (Angel Wing, Developmental Leg Deformities, Splay Leg) are most likely to be seen in chicks, but milder forms of these deformities may still be present in older birds.

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General internal examination 

  • At this stage, if not before, the carcass should be wetted to minimise feather debris; a wetting agent can be used such as dioctyl sulgosuccinate, or disinfectant solution.
  • Pluck feathers along the midline as required.
  • The wings can be fixed to the dissection board by pins inserted between the radius and ulna at the distal end of the forelimb.
  • Slit the skin from the vent to the bill in the ventral midline: nick the skin over the breast muscles in the midline, continue the incision rostrally (forwards) to the bill and caudally (backwards) to the cloaca (vent), taking care not to damage underlying tissues.
  • Reflect the skin from the neck, chest and abdomen.
  • Note the amount of subcutaneous fat, amount of breast muscle present, the thymus in young birds, the colour of subcutaneous tissues, any bruising, haemorrhage or other lesions, the condition of the external surface of trachea and oesophagus, any distension/impaction of oesophagus, the presence of haemorrhage, pale areas or e.g. 'rice grain' lesions in breast muscles, the presence of haemorrhage in neck muscles.
  • Cut through to and disarticulate the hip joints.
  • Remove the sternum and rib cage: incise transversely (across the body) just below the sternum, lift the sternum upwards and, noting the condition of the air sacs, cut through the rib cage and coracoid on either side using necropsy shears or scissors (as appropriate for the size of the bird).
    • Take care not to touch the liver, heart or lung surfaces during this procedure.
    • The air sacs should be transparent, glistening membranes.
  • Note the presence and type of any fluid or fibrin tags within body cavity, any gross abnormalities (e.g. gross haemorrhage) and the general layout and appearance of the heart, lungs, air sacs and liver.
  • If appropriate take samples from surfaces before any contamination can occur.
  • Note that there is no diaphragm, but there is a membranous pulmonary fold caudal to the lungs.
  • A scintillating sheen of urate crystals may be visible over the viscera in a bird with visceral gout. (B14)
  • Note how much fat is present and whether any fat shoes serous atrophy.
  • Note:
    • All parenchymal organs should be sliced repeatedly, to minimise the risk of missing focal lesions.
    • Tissues sections for fixation should be no more than 5 mm thick and should be placed into at least 10 times the volume of formalin compared to the piece of tissue.
    • The air sacs should be placed on a small piece of paper before fixation; this reduces the risk that they will be accidentally discarded.
    • Preferably fix complete sets of tissues.
    • If gout is suspected, tissues should be fixed in absolute alcohol.
    • For virology, freeze tissues preferably in an ultra-low-temperature freezer.

(B13.14.w19, B36.2.w2 - full text included, B64.App14.w10, D440, P4.1988.w1)

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Cardiovascular system

  • Examine the pericardial sac. There should be little fluid in the pericardial sac.
  • Prepare cultures and smears from heart blood if appropriate.
    • From freshly-dead bird, blood smears should be made from both heart blood and peripheral blood to look for haematozoa. (D440)
  • Dissect out the heart, leaving a portion of the major blood vessels intact.
  • Weigh the heart to detect any enlargement.
  • Examine the heart: overall shape, pericardium, fluid in pericardial sac, epicardial surface - any haemorrhages, presence of worms visible under surface, thickness of ventricle walls, presence and amount of blood in ventricles, state of valves, colour of muscle: haemorrhages or pale areas within muscle or on endocardial surface.
    • Normal findings: pericardial sac clear/translucent, containing a trace of clear fluid. Epicardial surface clean, glistening, heart contracted, triangular. Coronary groove separating the atria from the ventricles and usually containing fat deposits; no external demarcation between the left and right ventricles.
    • Opening up the four chambers, the left ventricle wall should be two to three times as thick as right ventricle wall, there should be little or no blood in the left ventricle, a small amount of blood in right ventricle. The atrioventricular valves should be smooth and shiny; the left atrioventricular valve resembles that of mammals but the right atrioventricular valve is a thick muscular ring, not tricuspid.
    • Note: In small birds the whole heart may be fixed in formalin.
  • Cut along the major vessels (e.g. aorta, jugular vein), check walls of vessels for presence of plaques, calcification.

(B13.14.w19, B36.2.w2 - full text included, B64.App14.w10, D440, P4.1988.w1)

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Respiratory system

  • Examine the lungs in situ, note their colour.
    • Normally pale pink
    • Dark red and wet-appearing with pulmonary oedema and haemorrhage.
  • To remove the lungs, use gentle traction on the trachea and oesophagus, while gently dissecting the lungs from the rib cage using the tip of a scalpel blade.
  • Cut through the lungs, noting any presence of water, froth, blood, fungal infection, abscesses.
  • Using sharp scissors, cut along the whole length of the trachea (it is necessary to cut along both sides, as the tracheal rings are springy) from the mouth, and along the major bronchi, noting any presence of fluid, blood, fungal plaques, necrotic lesions, blockage, parasites (tracheal flukes, gapeworm).
  • There is normally a syrinx, a structure at the bottom of the trachea formed by fusion of the lowest cartilaginous rings to form a cylindrical tympanum. (D440)
  • Normal lungs should appear pink and well aerated; the cut surfaces should be moist and glistening, often with a lot of blood present.
  • N.B. if the bird drowned, there may be water in air sacs and lungs, or just the lungs if there has been a delay in examination.

(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)

Waterfowl Consideration
  • In male ducks there is a cartilaginous enlargement around the syrinx. (D440)
  • In swans, part of the trachea is found inside the sternum. (D440)
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Liver 

  • Examine the liver in situ, note its size, shape, colour, any haemorrhage on surface or free in body cavity, whether surface is intact or split, presence of pale areas, whether lesions are flush with surface or protruding or shrunken, whether edges of lobes are sharp (normal) or rounded (enlarged).
    • The liver is yellow and swollen with hepatic lipidosis, but also in neonatal chicks still absorbing the yolk sac.
    • With diffuse haemosiderosis the liver may be diffusely yellow-orange.
    • Multifocal pale foci (necrosis) suggests viral, bacterial or chlamydial infection.
    • The liver may be paler than normal in severe anaemia.
  • Remove the liver, carefully cutting connections with other tissues.
    • If the liver is left attached to the intestines initially, until after the gastrointestinal tract has been examined, then the patency of the common bile duct can be checked by pressing on the gall bladder and observing flow of bile into the duodenum.
  • Weigh the liver to assist in detecting any pathological enlargement.
  • Touch preparations should be made of the intact surface to detect elementary bodies of Chlamydia psittaci.
  • Cut through the liver several times, note colour variations, the size and shape of any lesions (pale areas, haemorrhages, abscesses).
    • The normal liver is reddish-brown and somewhat friable; there are left and right lobes.
  • Note the size of the gall bladder.
    • Ostrich, many psittacines and most Columbidae lack a gall bladder. (D440)
  • Take tissue/swab for culture, impression smears from cut surface, tissue for histology and toxicology (e.g. lead levels in waterfowl) as appropriate.
    • Plasmodium spp. and Chlamydia may be visible in impression smears from the cut surface. (D440)
  • The whole liver should be sliced into multiple sections ("bread-loafed" to minimise the risk of missing seeing focal lesions.

(B13.14.w19, B36.2.w2 - full text included, B64.App14.w10, D440, P4.1988.w1)

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Spleen

Identify and examine the spleen before it has become contaminated as a result of manipulation of the viscera.
  • The spleen lies between the proventriculus and gizzard, on the right side. It can be found by grasping the gizzard with forceps and rotating it anticlockwise, transecting the ligamentous attachments between the gizzard and the left ventral abdominal wall as required, to visualise the spleen on the cranial portion of the gizzard.
    • Note that the normal size and shape of the spleen varies between bird species (e.g. oval and relatively large in pheasants).
  • Weigh the spleen to assist in detecting any pathological enlargement, but note that there are also physiological causes of enlargement.
  • Note the colour: normally red-brown; tan and swollen with viral, bacterial and some protozoal infections.
  • Make impression smears of the cut surface, take a small piece for culture and fix the remainder.

(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)

Waterfowl Consideration
  • The spleen is normally small and flat. (B36.2.w2 - full text included) May be triangular. (D440)
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Kidneys / Urogenital system

  • Examine kidneys, adrenals, and reproductive tract in situ, including size and colour of kidneys, presence of haemorrhage or pale areas (e.g. with renal coccidiosis, presence of chalky material if uric acid build up. Examine gonads: size, whether ovary is active (follicles present and growing) or inactive, appearance of oviduct, presence of egg within the oviduct or the abdomen, presence of associated reaction if egg or yolk is present free within body cavity, any haemorrhage. Remove kidneys (this requires careful dissection, as they are in bony recesses), adrenals, gonads
  • Incise and examine the organs. The parenchymal organs should be sliced repeatedly "bread loafed" to minimise the risk of missing focal lesions.
  • The kidneys are paired, lobular, normally reddish-brown, found recessed on either side of the vertebral column, stretching from the lungs caudally to the last segment of the synsacrum.
    • Look for discolouration, swelling, pallor, pale or dark foci, masses, lineal white foci (indicative of gout).
  • The ureters are paired, running from the most cranial lobe of the kidneys to the urodeum and if normal are difficult to identify; they are visible if they are distended by urates.
    • There is no bladder. (D440)
  • The testes in males are normally oval to elliptical, found craniomedial to the cranial division of the kidney on either side, caudal to the abdominal air sacs and the lungs, and dorsal to the main abdominal viscera (gastrointestinal tract, liver, spleen).
    • These are generally yellow in immature birds. (B13.14.w19)
      • In mature males in the breeding season these may be quite large; they are usually white and the surface appears vascular.
    • The colour varies between species (sometimes melanistic). (D440, B13.14.w19, )
  • Female birds normally have a single ovary, the left ovary, found ventral to the cranial division of the left kidney, and a single, left, oviduct.
    • Paired ovaries are normal in some species.
    • Immature: somewhat triangular, grey, with a rough-looking surface (immature follicles) and an inconspicuous narrow tubular oviduct extending to the cloaca.
    • Record the appearance of the ovary; look for developing follicles - there should be vascular yellow follicles, varying in size in reproductively active females
    • The oviduct in reproductively active females is a large tubular organ, off-white, flaccid, vascular and on the luminal surface, rugose.
    • Look for lesions in the oviduct including inflammation (indicated by thickening of the distal wall of the oviduct), which indicates egg binding.
    • Note if a fully-formed egg is present. In rarer birds this should be collected intact as it may be useful for specific studies. (D440)
    • If salmonellosis is suspected, take ova for bacteriological examination since some Salmonella spp. can be transmitted transovarially. (D440)
  • Note: sex determination may be difficult in hatchlings.
  • In Anseriformes and ratites the penile organ should be examined (in other species it is vestigial).
(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)
Waterfowl Consideration Check the penile organ. (D440)
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Gastro-intestinal System 

  • Examine the gastro-intestinal tract in situ, note any distension, discolouration, haemorrhage or lesions on serosal surface, size, shape and colour of spleen (normally small and flat in waterfowl).
  • Tie off oesophagus at top of neck, cut above this, remove whole of gastro-intestinal tract.
  • Examine the whole of the gastro-intestinal tract, including pancreas.
    • If the contents of different segments of the gastrointestinal tract are to be submitted separately for culture, they should be tied off with string at this time.
  • There is a crop - a diverticulum of the oesophagus - in some species, particularly well developed in pigeons, gallinaceous girds and psittacines. In pigeons, it is divided into two lateral glandular sacs; these produce crop "milk" for feeding chicks. In psittacines the crop is found transversely across the base of the neck.
  • Check the serosal surfaces, note any adhesions, haemorrhage etc.
  • Open each region (oesophagus, crop if present, proventriculus, gizzard, small intestine, large intestine, caecae, cloaca) longitudinally using scissors. Check for: haemorrhage (N.B. agonal bleeding and post mortem leakage must be distinguished from haemorrhage into gut), ulceration or other lesions, presence of parasites and whether lesions are associated with these, presence and appearance of ingesta, including recognizable food items in the oesophagus, crop and gizzard, and any foreign bodies.
    • Keep ingesta (e.g. plant pieces from the oesophagus/crop/gizzard) for analysis if appropriate.
    • Remove any parasites, preserve for identification.
    • Examine the mucosal surface of each part of the gastrointestinal tract.
    • In the gizzard, having inspected the luminal surface, peel back the koilin layer and examine the glandular surface.
    • The gizzard in seed-eating birds has a thick muscular later and a hardened cuticle, the koilin or "keratinised layer".
    • In penguins the stomach is distensible and reaches to the posterior abdomen. (D440)
    • Place a section from each segment of the GIT into formalin for preservation.
    • Not all species have caecae, and some only have one.
  • Fresh samples of contents and mucosal scrapings of duodenum, ileum, caeca may be examined microscopically for parasitic ova and coccidial oocysts, also smears may be Gram stained.
    • Do not submit sections for histopathological examination after scraping with a scalpel, as the specimen will be damaged and probably contaminated.(D440)
  • Flush out the gizzard contents into white bowl, examine for presence of lead shot and other foreign bodies, note colour of gizzard lining and whether it is normally adherent to the underlying tissue and whether it can be peeled out.

(B13.14.w19, B36.2.w2 - full text included, B64.App14.w10, D440, P4.1988.w1)

Waterfowl Consideration
  • There is no prominent crop, just a spindle-shaped swelling of the oesophagus near the thoracic inlet. (B36.2.w2 - full text included, D440)
Crane Consideration

Foreign bodies in gizzard. Click here for full-page view with caption.

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Glands

  • In young birds, the thymus is found in the jugular furrows, appearing as a series of connected lobes, greyish or pale pinkish in colour. These extend into the thoracic inlet.
    • In some species the thymus may re-enlarge after the breeding season. (D440)
  • Examine the thyroid and parathyroid glands:
  • The thyroid and parathyroid glands are found closely associated with the jugular vein and the first rib, at thoracic inlet, at the level where the carotid arteries divide, with the parathyroids just caudal to the thyroid glands.
    • The thyroids are paired, ovoid dark red or reddish brown. The parathoids are small and yellowish and may not be visible unless enlarged (dietary-induced secondary hyperparathyroidism).
  • The adrenals are immediately dorsal and anterior to the gonads, irregular oval in shape and normally yellowish-orange.
    • These may be enlarged with chronic stress.
  • The bursa of Fabricius should be examined in immature birds; this is found adjacent to the cloaca/vent.

(B13.14.w19, B64.App14.w10, D440, P4.1988.w1)

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Nervous system

  • Examine the brachial nerve plexus before removing the thoracic viscera; consider sampling if these is suspected neurological damage
  • Examine the sacral plexus after removing the kidneys, particularly in instances of pelvic limb paresis/paralysis (or muscle wastage indicating this).
  • If there was pelvic limb paresis/paralysis (or muscle wasting indicative of this), check the ischiatic nerve (caudal to the femur, under the medial muscles of the thigh) and send for histopathological examination.
  • For access to the brain, cut through cranium on both sides from foramen magnum forwards, keeping scissors or shears perpendicular to surface to minimize damage to brain and lift off.
    • In small birds, curved iris scissors may be adequate to cut through the skull, while in larger birds, rongeur forceps or even an autopsy saw may be used.
  • Examine the brain in situ, note any haemorrhage (N.B. agonal bleeding may produce blood in cranial bone, but haemorrhage in meninges or brain tissue should be considered significant); greenish bruising is more likely to be older. Cut the brain sagittaly, retain samples for toxicology.
    • It may be preferable to fix the whole brain and slice vertically after fixation. (D440)
  • For access to the spinal cord, snip segments from the vertebral column and fix in formali; the cord segments can be removed once the tissues are fixed.
  • If a nerve plexus is to be submitted for histopathology, gently press flat on card and leave for a few minutes before fixing. (D440)
(B13.14.w19, , B64.App14.w10, D440, P4.1988.w1)
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Egg Necropsy

FOR BIRDS:

HISTORY: Egg history is an important part of egg necropsy and the following details should be recorded:-

  • Species, identity and previous breeding history of the adult birds.
  • Date that the egg was laid.
  • Details of incubation:
  • Parent, broody or artificial incubation.
  • Any known disturbance of incubating birds.
  • Incubation records - incubator type, records detailing intended incubator settings and actual temperature, humidity, turning, ventilation etc.
  • Whether eggs were stored before incubation and if so details of storage length of time, temperature, turning.
  • Period of incubation (normal incubation time for this species, actual time egg incubated prior to necropsy)
  • Results of any egg inspections (candling, flotation) during incubation.
  • Initial weight of egg, record of weight loss.
  • Whether other eggs from this clutch and/or in the same incubator have failed to hatch and if so what percentage.

EXAMINATION OF THE EGG:

  • Examine external surface. Note any: blotchiness/discolouration, oozing, cracks, presence of dirt, any identifying number for records, if there is chipping/pipping of shell and whether the bill is visible if pipping has occurred.
  • Weigh and measure length and width. (N.B. small eggs may be associated with salpingitis). Photograph egg.
  • Candle the egg. Note whether the egg appears probably infertile (clear) or probably fertile. Sketch any findings.  - size and position of air space, size and position of embryo if visible, any other findings.
    • Candling assists in choosing the best point at whichto enter the egg, and allows development of correlations between candling appearance and egg necropsy findings. (P4.1991.w1)
  • Open the egg. Clean the shell with 70% alcohol (methanol) and allow to dry. The shell may be opened by removing an elliptical piece of shell over the long axis of the shell (P1.1989.w1, B116.9.w1), or by removing a piece of shell over the large end, i.e. over the air cell (B11.11.w20). Puncture the shell with a sharp pair of scissors, remove a sufficiently large piece of shell to visualize the contents of the egg, and place this to one side. Note shell thickness, state of membranes if dead-in-shell. [Long-axis approach may give better visualization of the yolk and any blastocyst (to distinguish fertile from infertile eggs), and of the position of the embryo, without affecting the yolk or aircell].
  • Examine the contents of the egg in situ: describe the contents, including a sketch and/or photograph as appropriate.
    • The general evaluation should be carried out before any of the contents of the egg are disturbed or punctured. Note the colour, size and locationof the albumin, yolk and allantois, the presence and characteristics of the circulatory tree, and any abnormal odours. (P4.1991.w1)
  • For eggs thought to be infertile: sample for bacterial, fungal, viral culture. Retain contents if required for toxicological examination (store at -20C), otherwise discard.
  • For eggs thought to be fertile:
  • Culture contents or swabs from different sites (depending on degree of development). Swab sites may include e.g. yolk, amniotic fluid, vitelline membrane. N.B. analysis of findings must take into account possibility of contamination of long-dead or infertile eggs by environmental bacteria.
  • Examine the embryo in situ for malpositioning. Note particularly the position of the bill and limbs if dead-in shell.
  • Remove embryo and associated tissues from egg.
    • if small, the embryo and the rest of the egg contents can be poured out of the egg into a sterile container. (P4.1991.w1)
  • Weigh and measure. N.B. note weight of embryo both including and without yolk sac. Measurements may include e.g. crown-rump length, culmen length, ulnar and tarsal lengths. An estimate of the age of the embryo should be made, although accurate age determination may be difficult as details of development are available for only a few species and estimates must take account of the normal incubation period for the species and whether the chicks are altricial or precocial (P1.1989.w1).
  • Examine the embryo as if it were a hatched chick. N.B. a dissecting microscope may be useful, and sketches and photographs taken as appropriate.
    • Small embryos may be fixed whole and sectioned. Larger embryos may be dissected, with samples of tissues taken for bacteriology, mycology, histopathology, virology or other tests and the remaining embryo may be fixed (10% buffered formalin, or alcohol or Bouin's solution) and kept.
    • Note any developmental abnormalities such as prognathia, hydrocephalus.
    • Check the hatching muscle for any oedema or haemorrhage and note its size. (P4.1991.w1)
    • Note the skin colour and any haemorrhage. (P4.1991.w1)
    • Check for any musculoskeletal abnormalities. (P4.1991.w1)
    • Note the contents of the mouth, nares and oesophagus and (if present) crop. (P4.1991.w1)
    • Check the lungs (note: determination of whether the chick has breathed, and whether it has inhaled fluid, will generally require histopathological examination). (P4.1991.w1)
    • Examine the yolk stalk and umbilicus with care.
      • With bacterial infection, there may be visible yolk lesions such as yolk sac haemorrhages and coagulation of the yolk, but not if the infection was overwhelming and death rapid. (P4.1991.w1)
      • N.B. the yolk sac and contents should be separated from other tissues and stored separately to avoid yolk droplets/granules confusing the histopathological findings.
      • Yolk sac may be used for culture, vitamin analysis, toxicological analysis.
  • Examine shell membrane, air cell, allantois, amniotic sac and fluid, yolk sac, contents and vitelline circulation.
  • Note:
    • Histological examination may be used to distinguish whether "suspicious material" on the yolk surface or in a severely addled egg is an early embryo or not.
    • Histopathological findings may be compromised due to the degree (often considerable) of autolysis, but may be useful both in determining the cause of death and in developing information on the normal histology of avian embryos.
    • Toxicological tests which may be carried out include those for chlorinated hydrocarbons, heavy metals and selenium.
      • N.B. for toxicological examination, freeze the egg/contents.
  • Shell: dry for seven days and weigh.
  • N.B. interpretation of the findings may be difficult. Even distinguishing between an infertile egg and an early embryonic death is difficult as eggs may be severely decomposed by the time of examination. Management factors affecting the parents, genetics, egg storage and incubation conditions (temperature, humidity, turning) as well as the effects of toxins, viruses, bacteria and fungi must be considered. Secondary infection is common and usually results in mixed bacterial cultures. Heavy growth of one or two organisms may be more likely to indicate a primary infection.

(B11.11.w20, B116.9.w1, B116.11.w2, P1.1989.w2, P4.1991.w1)

Waterfowl Consideration --
Crane Consideration

Swabbing unhatched egg for culture. Click here for full-page view with caption.

  • Necropsy of 44 whooping crane eggs/embryos revealed that 24/44 (52%) died during the last third of incubation. Causes of death included:
    • Malposition of the embryo in seven (16%) (29% of those dying in the last third of incubation).
    • Haemorrhage/trauma in seven (16%)
    • Failure of natural incubation failure in five (11%) or of artificial incubation in four (9%)
    • Other causes of death in two (5%).
    • Note: In 19 cases, necropsy did not reveal a specific cause of death.

    (P87.11.w5)

Associated techniques linked from Wildpro
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Human Health Consideration

  • Potential hazards to human health of ANY necropsy or post mortem examination must be considered before undertaking examinations and personnel undertaking or attending necropsies or post mortem examinations must be made aware of the potential hazards to human health.
  • Potential hazards range from toxins on the surface of the animal (e.g. oil) to zoonotic diseases which may be transmitted through cuts, absorbed through mucous membranes or inhaled in the form of dust or aerosols.
  • Important zoonotic diseases to consider in dealing with bird carcasses include Aspergillosis, Avian Tuberculosis, Chlamydiosis / Psittacosis, Erysipelothrix Infection, Salmonellosis and Yersiniosis.
  • For all necropsies, protective clothing should be worn, particularly disposable gloves (which should be replaced immediately if damaged). A face mask is advisable.
  • If possible, necropsy should be carried out inside a protective cabinet.
  • Any cuts should be washed immediately with a disinfectant soap.

(B11.11.w20, B36.2.w2 - full text includedB96.w2)

Waterfowl Consideration
Crane Consideration
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Records

  • Complete records should be kept including the species, any rings/bands/tags, microchips or other identifying information, any age/sex information, location of origin, whether captive or free-living, who presented the carcass for examination etc.
  • The general state of the carcass should be reported - fresh or degree of composition, whether whole or not, whether refrigerated or frozen before examinations, time from death/the carcass being found.
  • A full record of the necropsy findings should be kept, preferably set out on a standardised form; necropsy records need to be properly organised and retrievable, or they are unable to be useful in ongoing health programmes.
    • Necropsy records should be properly linked to other records regarding the individual, such as its health records and history (for birds within a collection; or for free-living birds whether the carcass was found alone or part of a die-off etc.)
  • A record should be kept of any samples taken, for what purpose (histopathology, bacteriology, virology, parasitology, detection of pesticide or heavy metal residues etc.
  • AVOID using non-standard abbreviations. Standard abbreviations (e.g. "NE" for "not examined", "NLD" for "no lesion detected") should be defined on the necropsy form.
  • Note: All samples should be properly labelled with identifying information, preferably including a unique identifier which will match the samples with the necropsy form and other appropriate records.
  • Records and good identification of specimens are particularly important when investigating deaths which may be malicious or may lead to prosecution or compensation claims (e.g. suspected poisonings, oiling).
  • If legal proceedings are possible, preferably have a witness present throughout the necropsy to confirm the accurate recording of findings and to witness labelling and sealing of possible forensic material. Additionally, keep the carcase deep frozen as well as suitably preserving the organs. (D440)

(B64.App14.w10, B36.2.w2 - full text included, D440, P4.1988.w1,  V.w5)

Waterfowl Consideration Complete records should be kept, as indicated above.
Crane Consideration Complete records should be kept, as indicated above.
Associated techniques linked from Wildpro

Authors & Referees

Authors Debra Bourne MA VetMB PhD MRCVS (V.w5)
Referee  

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