Applying the general necropsy protocol, the process should always be carried out in an orderly, complete and systemic manner.
In the case of birds, the background of the animals is of special importance, differentiating between individual necropsies or necropsies of animals belonging to collectives.
- Individual: They can be performed on caged birds found in homes or on wild animals found dead in the field. Their main purpose is to determine the cause of death of the animal.
- Collectivities: They are performed mainly in the case of production animals and, to a lesser extent, in wild animals, where the appearance of several dead animals is indicative of a possible group pathology. In this case the objective is the identification of the etiological agent causing the determined problem, which could be an infectious disease of relevance in the field of production or even a zoonosis. It is advisable to consult the notifiable diseases in poultry production in Spain (RD 526/2014).
In addition, it is convenient to collect a number of live individuals of the same group that present clinical signs in order to proceed to their gross and histopathological study.
First, an inspection of the entire body surface should be performed, assessing the integrity of feathers and appendages (wings and legs).
It is convenient to wash the animal with a disinfectant solution (alcohol) to avoid the dispersion of feather dust and possible potential pathogens.
Necropsy in a bird. External examination
Assessment of the body condition and the state of the musculature, by evaluating the pectoral angle and the prominence of the keel.
Inspection of external orifices: oral and pharyngeal mucosa and cloaca.
A cut is made at the level of the commissure of the beak at the level of the left commissure, to continue cutting the skin on the left side of the neck, the crest of the sternum and following the median until reaching the cloaca. All the skin is dissected, removing it laterally and assessing the state of greasing.
Necropsy in a bird. Internal examination of the coelomic cavity
If the size of the bird allows it, disarticulation of both hips for greater comfort in performing the necropsy and better position of the bird in supine recumbence.
Execute an incision immediately caudal to the sternum and make two cuts dorso-laterally to both sides, following the edge of both pectoral muscles until reaching the shoulder joint. In this path, section the ribs, coracoids and clavicles, taking special care not to damage the organs present in the coelomic cavity.
Remove the structure of the sternum and pectoral muscles first to the side to assess the cranial thoracic air sacs. Subsequently, detach this structure completely from the other side, making the complete opening of the cervical musculature from the chest to the beak and the abdominal musculature from the chest to the cloaca.
Examination of the coelomic organs
At this point, with the entire cavity visible, perform visual inspection of all organs and serosae, before proceeding with the extraction. Determine the presence of celomc effusions (ascites, hemoceloma, etc.), intra-celomical laying with associated peritoneal reaction, infectious processes (aspergillosis), deposits (visceral gout), among others.
First section the vascular trunk of the heart and remove it completely together with the pericardium, to proceed to its opening by means of a transversal cut from the apex to the base.
Locate in the most cranial portion of the chest and in the neck the thyroid and thymus, especially in young animals, and extract it.
Make a cut at the level of the esophagus, at the level of the carina (tracheal bifurcation) and extract it caudally together with the proventriculus, gizzard, pancreas, liver, spleen and intestines, including the cloaca and the oviduct in its case. Take special care not to incise the gall bladder, avoiding releasing the content into the cavity.
In young or sick birds, evaluate the bursa of Fabrizio, located on the dorsal side of the cloaca, in intimate contact with the pelvis.
Make a cut of the oro-pharyngeal mucosa to remove the trachea and esophagus ventrally until extracting them together with the lungs, intimately linked to the ribs.
Remove the kidneys together with the gonads and adrenals. In many species the kidneys are very attached to the sacrum, making it a dedicated process.
Assess the nerve plexuses in the carcass: brachial, at the level of the thorax in its exit towards the forelimbs; and sciatic, at the level of the abdomen in its exit towards the hind limbs. Take samples of nerve tissue from both areas.
Examine each organ separately, taking the corresponding samples.
Perform the opening of the proventriculus, gizzard and separate the intestinal loops, examining the pancreas and opening the intestine and cecum (if present) in its entire length.
Opening of the cranial cavity
Dissect the skin of the skull along the sagittal midline, to make a circular cut of the bones through the occipital portion towards the posterior part of both orbits. Remove the cranial vault and extract the brain.