1 Necropsy technique in poultry Preparation of the cadaver and opening the coelomic cavity
2 HOW TO NECROPSY A BIRD
3 Recognizing and recording abnormalities are enhanced by developing a consistent routine in the dissection and collection of tissues. There is often a tendency to move quickly to the suspected lesion or body system, which risks missing important information. A good necropsy involves paying attention to ALL the clues that can be provided, so the routine has to be followed, with attention to detail at every step.
4 The steps to be followed by dissecting dead chicken:1. Obtain the history 2. Examine the animal externally 3. Open the body 4. Remove the organs and set aside for detailed examination and sampling 5. Examine and sample the organs 6. Write the report
5 1. Obtain the history A good individual animal and flock history should be obtained. This history should include: 1. Bird’s age 2. Sex 3. Breed 4. Clinical signs 5. History of trauma or disease 6. History of any treatments administered 7. Any other information that may be relevant to the case such as type of feed and water
6 8. If the bird is a member of a flock the following is also required: • Number of birds in the flock • Number of birds in the affected group • Number of affected birds • Clinical signs of the flock should also be noted A proper history can help in determining what samples should be taken and what tests are necessary for making the correct diagnosis.
8 The skin, feathers, eyes, ears and beak should be examined for any abnormalities. Take a close look at the comb and wattles -any swelling? Discoloration? Look at the back of the bird for evidence of feather picking. If any skin lesions are noted, they should be sampled. Examine all mucous membranes (mouth, nares, and conjunctiva for any discoloration or other abnormalities. How about the cloaca? Any diarrheal staining? Urates present? Trauma? Look at the joints - any swelling?
10 Dip the whole carcass into a bucket of soapy water to thoroughly wet all the feathers - this willdecrease the dander that might aerosolize from the skin and will also keep your instruments free of small feathers as you do the dissection.
11 3. Open the body Unlike mammals, birds do not have two cavities, thoracic and abdominal, but just one internal cavity called the coelomic cavity, where most of the vital organs are found, to open the coelomic cavity, make a cut in the area located below the breast using a pair of scissors (fig. 1).
14 Next, make two small lateral cuts until reaching the ribs, and with the help of the bone cutting forceps cut the ribs (in the cranial direction) (fig. 2),
21 4. Extraction of the internal organsThe coelomic cavity organs are removed together. To achieve this, a cut is made in both commissures of the beak (fig. 6) and in both sides of the hyoid bone, exposing the oral cavity (fig. 7). An incision is made in the soft palate region (fig. 8) and the trachea and the oesophagus through to the crop are cut and removed together by gentle traction. Continue cutting until reaching the heart, and then again with gentle traction and helped with the tips of the scissors, separate the lungs from the dorsal region of the coelomic cavity.
25 It is probably easiest to remove the abdominal viscera first and then go back and remove the thoracic organs. The liver and the gastrointestinal tract are extracted whole together with these organs. Simply pull gently with the hands towards the caudal region, where the rectum remains attached to the animal in the cloacal region.
27 Find the junction of the esophagus and stomach, cut here and pull the digestive tract out, all the way to the cloaca. The digestive, urinary, and reproductive tracts come together at the cloaca.
28 Bursam of Fabricius The bursam of Fabricius is the light cream-colored saccular organ, located in this cloacal region, and it should be extracted with the rest of the organs from the coelomic cavity. The bursa of Fabricius contains lymphoid follicles and can be easily found in young birds. Once the bird reaches sexual maturity, it undergoes involution and therefore becomes smaller as the bird ages.
29 Like the thymus, this organ is not present throughout the animal's life, but involutes between 14 and 20 weeks. Once the bursa is localized, a U-shaped incision is cut around it, so that most of the organs of the coelomic cavity have been removed.
31 In the case of adult hens, the reproductive system is also found in the coelomic cavity which is extracted along with all the organs, as is the digestive system. Only the genitourinary system will remain in the interior of the coelomic cavity, and the reproductive system (testis and oviduct) in the case of young birds.
32 Kidneys Kidneys three portions -cranial, middle and caudal poles. The reproductive tract lies on top of and at the cranial end of the kidneys. Although the kidneys are examined in situ, it may be necessary to extract them for sampling. To extract the kidneys, which are totally inserted into the pelvis bones, the best system is to exert a slight pull from the medial and caudal region of the kidneys with forceps, and with the tip of the scissors to help extraction .