تشريح دواجن

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تشريح دواجن

  1. 1. 1POULTRY NECROPSY MANUALThe BasicsRecognizing and recording abnormalities are enhanced by developing a consistentroutine in the dissection and collection of tissues. There is often a tendency to movequickly to the suspected lesion or body system, which risks missing importantinformation. A good necropsy involves paying attention to ALL the clues that can beprovided, so the routine has to be followed, with attention to detail at every step.The consistent routine entails 6 steps:1. Obtain the history2. Examine the animal externally3. Open the body4. Remove the organs and set aside for detailed examination and sampling5. Examine and sample the organs6. Write the report
  2. 2. 2STEP 1. Obtain the historyA good individual animal and flock history should be obtained. This history should include:• Bird’s age• Sex• Breed• Clinical signs• History of trauma or disease• History of any treatments administered• Any other information that may be relevant to the case such as type of feed and water• If the bird is a member of a flock the following is also required:o Number of birds in the flocko Number of birds in the affected groupo Number of affected birdso Clinical signs of the flock should also be notedA proper history can help in determining what samples should be taken and what tests arenecessary for making the correct diagnosis.STEP 2. Examine the bird externally• Examine the bird for any signs of trauma and evaluate the bird’s general body condition.o If possible the bird should be weighed.o The keel bone should be felt to determine if there is any pectoral muscle atrophy.• The skin, feathers, eyes, ears and beak shouldbe examined for any abnormalities. Take aclose look at the comb and wattles - anyswelling? Discoloration?• Look at the back of the bird for evidence offeather picking.• If any skin lesions are noted, they should besampled.• Examine all mucous membranes (mouth, nares,conjunctiva) for any discoloration or otherabnormalities. How about the cloaca? Anydiarrheal staining? Urates present? Trauma?• Look at the joints - any swelling?
  3. 3. 3• Prior to opening the body, you might want to swab the trachea or cloaca. Whenswabbing the trachea, insert the swab up in the choana, as depicted in the photograph onthe left below, prior to inserting in the trachea.• Dip the whole carcass into abucket of soapy water tothoroughly wet all the feathers -this will decrease the danderthat might aerosolize from theskin and will also keep yourinstruments free of smallfeathers as you do thedissection.STEP 3. Open the body• The body should be placed on its back with its feet facing you.• Reflect the wings back.• Cut through the skin between the legs and the breast so the legs can be fully abducted andlie flat against the table.• Remove the skin from the ventral surface of the bird by cutting across at the caudal edgeof the keel and then pulling skin cranially and caudally - peel away from the muscle toexpose the muscular body wall.• Make a small cut into the body cavity using scissors or a scalpel blade - just behind thebreast bone, then pull the abdominal muscle caudally to expose some abdominal viscera.
  4. 4. 4• Extend the cut up through the cervical area and cut open the beak at the angle of the jaw.Now oral cavity, esophagus, trachea and crop are all visible.• The keel bone and breast muscle is then removed by incising the pectoral muscles oneach side of the keel and cutting through the ribs. Use the heavy poultry shears. Removethe keel and breast muscles entirely - you should now be able to see the internal organsfrom oral cavity to rectum.
  5. 5. 5• At this point, all internal viscera should beexamined in situ for any abnormalitiesbefore removing any organs. Note thecolor, position and size of all organs andlook for any adhesions.• Examine the air sacs for increasedthickness or cloudiness (caudal thoracicair sac is at the end of the forceps).STEP 4. Remove the organs and set aside for examination• Identify the thyroids and parathyroids, which are in a different location than in mammals,and found as paired structures at the thoracic inlet.
  6. 6. 6It is probably easiest to remove the abdominalviscera first and then go back and remove thethoracic organs.Remove the liver - in birds the liver takes up abig portion of the abdomen.The spleen can be a difficult organ to find onceeverything is removed so it is a good idea tolocate it now and set it aside. It is spherical inshape and located on the right side at thejunction of the proventriculus and ventriculus.Pull the proventriculus aside and it should popinto view. Take it out now and set it in a cleandry spot.Find the junction of the esophagus and stomach, cut here and pull the digestive tract out, all theway to the cloaca. The digestive, urinary, and reproductive tracts come together at the cloaca.Located in the cloaca is the light cream-colored saccular organ,the bursa of Fabricius. Thebursa of Fabricius contains lymphoid follicles and can be easily found in young birds. Once thebird reaches sexual maturity, it undergoes involution and therefore becomes smaller as the birdages.Cut at the end of the large intestine, but leave the bursa in the bird.Here are two views of the bursa - undisturbed (left) and incised (right).
  7. 7. 7Kidneys are nestled up against the body wall - there are three portions - cranial, middle andcaudal poles. The reproductive tract lies on top of and at the cranial end of the kidneys. Photos -mmediately below is a male (left immature; right mature); lower two photos are an immaturefemale (left) and a mature female (right). In females only the left side of the tract persists, theright is vestigial and too small to be identifiable.Adrenal glands are often difficult to find. Here they are lyingjust cranial to the testes in an immature male.Pull the heart and lungs away - the lungs are closely adhered to the dorsal body wall, andtherefore, careful teasing of the lungs away from the ribs may be necessary to remove them.
  8. 8. 8Open up the nasal cavity to take a close look at thesinuses.Observe the sciatic nerve which is an importantlocation where Marek’s disease can be seen.Open some joints to observe the fluid and synovialmembranes.The brain can now be removed. Using the smallerscissors (not poultry shears), chip away at the skull,beginning from the foramen magnum, and removethe calvarium covering the cerebral hemispheresand the cerebellum. Take the brain out - use care,this organ is quite soft.
  9. 9. 9STEP 5. Examine and sample the organsIt is a good idea to go from the “cleanest” organs to the “dirtiest. Usually this order is:lymphoid tissue, brain, lungs, heart, kidneys, reproductive tract, liver, intestinal tract.Note any abnormalities for each (color, size, shape, consistency, exudates). Be sure to examineboth capsular and cut surface. Make several cuts in each organ. Collect specimens for furtherdiagnostic work.Lymphoreticular systemSpleen in birds is a small round organ that should be a uniform mahogany color on capsular andcut surfaces.
  10. 10. 10Bursa changes dramatically with age. Birds older than10 weeks will have a bursa that may evenbe difficult to locate. A normal bursa in a young bird has an accordion-like structure and is ahomogeneous tan.BrainOften the brain is sliced down the middle tocreate symmetrical halves for frozen andformalin specimens.HeartThe heart cannow be examined.Make one incisioninto eachventricle, examinemuscles andvalves.Respiratory systemBegin by cutting through the larynx, trachea, and syrinx making note of any mucus, froth, orpetechiae. Lungs should be pink, “spongey”, and free of any fluid.
  11. 11. 11KidneysThese should be smooth and homogeneous. Areticular pattern is an indication of dehydration.Reproductive tractTestes are homogeneous oncapsular and cut surfaces.Ovaries should be free of inflammation. Sterile egg yolk peritonitis is a common finding in“spent” layers.LiverThe liver’s surface should be examined forany abnormalities. It should be palpatedfor any nodules, friable areas, or otherabnormal changes. Several slices are madeinto the liver in order to examine thedeeper structure of the liver.Intestinal tractLook in the mouth for any abnormalities.Cut down the esophagus and see howmuch food is in the crop.
  12. 12. 12Open the proventriculus and make noteof the lining which is normally bumpy dueto the presence of digestive glands. Noteany abnormalities.The ventriculus, or gizzard, should beexamined next. Because the gizzard isresponsible for grinding ingested material,it has a thick external muscularis layer andcontains small stones or grit. Theventricular glands secrete a thickprotective gel, known as koilin, which hasa yellowish color. The gizzard thicknessshould be examined and the surfaceexamined for erosions, ulcerations,discoloration, or other abnormalities. Peelthe koilin back to look at the mucosa.The proventriculus-ventriculus junction(arrow in middle photo) is an area withabundant lymphoid tissue and should beexamined carefully for lesions.proventriculusventriculus
  13. 13. 13The small intestine of birds istypically arranged into severalloops before entering the colon.The first loop is the duodenum.It is easily identified by thelocation of the pancreas withinthe duodenal loop mesentery.The remaining loops make up thejejunum and ileum. The colon isrelatively short with two longceca and connects to the cloacavia the colorectum.In this picture you see the twoceca and the large colon inbetween. There are largelymphoid patches in the proximalportions of the ceca.Sampling of organs -• Tissues should be collected in duplicate, with half going into 10% formalin forhistopathology and half as unfixed tissues that will be used for bacterial culture, virusisolation, fluorescent antibody testing, toxicology, etc.• The following tissues should becollected in all cases: lung, liver,spleen, bursa, brain, kidney, intestines.Additionally, any other tissue that mighthave lesions (skin, adrenal, ovary, etc.)should also be collected.• Label the tissues that are collected freshso that the technician performing thetests can determine what each tissue is.• Crushing should be avoided whentaking samples since this may causeartifact histologically. This can beavoided by using a sharp blade and ahard surface.
  14. 14. 14• When examining any organ with a mucosal surface (trachea, esophagus, intestine, etc.)care should be taken not to damage or destroy the mucosal surface by rubbing the surfacewith fingers or instruments.• In order to improve fixation of tissues, samples should not exceed 5mm in thickness andvolume of fixative should be at least 10 times the volume of tissue.Fresh samples should be packaged so that they remain cool and to minimize possibilities ofleaking. Be sure to submit the proper paperwork to accompany the samples.STEP 6. Write the reportNo necropsy is complete until all findings have been recorded in written form. The report shouldinclude at least the following information:− Species, breed, age, sex− History− Died or euthanized?− Nutritional, hydration status− Findings from external examination− Findings by organ system: Lymphoreticular (spleen, bursa), Respiratory, Digestive,Urogenital, Musculoskeletal, NervousText and photos by: Corrie Brown, Raquel Rech, Daniel Rissi, Taiana Costa, Department ofPathology, University of Georgia, Athens, GeorgiaWhen describing tissues, keep these four qualities inmind - consistency, color, size, and symmetry.

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