POSTMORTEM PROCEDURE OF WILD ANIMALS

POSTMORTEM PROCEDURE OF WILD ANIMALS

Deepak Kumar¹, Sanjay Kumar² and Savita Kumari³

¹ Assistant Professor, Department of Veterinary Pathology, Bihar Veterinary College, Patna

² Assistant Professor, Department of Animal Nutrition, Bihar Veterinary College, Patna

³ Assistant Professor, Department of Veterinary Microbiology, Bihar Veterinary College, Patna

Post-mortem examination is a systematic and scientific observation of the carcass/cadaver with the objective to know the cause of death. Necropsy should always be thorough and systematic. However, in certain veterolegal cases where foul play is suspected in causing death of the animal, investigation is supposed to be conducted following registered police complaint. A necropsist is expected to reveal approximate time of death of the animal, the details of the injuries of the type of weapon used in committing crime and purpose of the crime. This aspect is more pertinent with respect to wild animals which are poached for their certain body parts having very high value in international market and smuggled across the border for medicinal, cosmetic or superstitious reasons. Many of the species have reached to endangered or nearly extinct category either through natural elimination in wild or through their rampant poaching. Wildlife Protection Act, 1972 came into being to protect endangered species to futher decline. Under this act each carcass of wild animals should be brought to record and thoroughly investigated not only to reveal cause but from forensic point of view too. Every wild animal death should be taken as veterolegal case until proved otherwise. The species identification and the knowledge of anatomic peculiarities are very crucial.

Materials required

1.Necropsy equipment

2.Personnel Protection kit

The team of veterinarians, assistants and attendants should wear protective clothing before the post-mortem examination of a dead wild animal. It is important to consider the circumstances of the illness and death of the animal and to assess the likelihood that the cause may have been a zoonotic or notifiable disease. Extra precautions must, therefore, be exercised when handling and dissecting animals, which may have died of a zoonoses.

1. Necropsy documentation

A photographer should be available for photographic documentation and a person should be made responsible for recoding gross changes.

• Digital high resolution
• Field notebook
• Postmortem proforma

2. Post Necropsy: sample collection, disposal and disinfection

TYPES OF NECROPSY

1. Where no necropsy is conducted i.e. Anthrax
2. Partial necropsy i.e. Rabies
3. Complete through necropsy
4. Cosmetic necropsy i.e. examination of the carcass is done with very less mutilation

For proceeding ahead to conduct postmortem of a veterolegal case or scheduled endangered wild animal, the following points should be kept in mind

1. The post-mortem should be conducted by written request from the police, the Magistrate or forest official.
2. The contents of the request letter should be read carefully before examination.
3. Time and date of arrival of carcass should be noted.
4. There should be no unnecessary delay in conducting post-mortem examination.
5. No unauthorized person should be allowed to be present at the time of post-mortem examination and the report should be sent to the concerned agency by registered post or sealed confidential envelope.
6. The particulars of identification marks of carcass furnished in the request memo should be checked and tallied with carcass received.
7. Additional particulars of identification of carcass may be noted in the post-mortem report.
8. The post-mortem examination should be done in day light or sufficient artificial light
9. The post-mortem examination should be thorough and complete with still or videographic documentation.
10. The details of lesions observed by the veterinarian should be carefully recorded in the postmortem report on the spot at the time of examination.
11.  A veterinarian must have fair knowledge of anatomic peculiarities of the species being examined.
12. The veterinarian and attendants are should be vaccinated annually for certain zoonotic diseases like rabies, leptospirosis and TB.
13.  Always a copy of report sent must be filed separately for future reference at the time of evidence in court.
14. The appropriate morbid materials must be collected, preserved and dispatched for desired laboratory investigations.
15. The details of specimens collected, sample of preservative used, sample of seal used, copy of postmortem report must be sent along with requisition letter for toxicological and other required examination.

Difficulties faced by veterinarians in conducting necropsy of wild animals:

1. Want of clinical history in free range wildlife and only in limited way in captivity.
2. Cases of sudden death.
3. Examiners are not familiar with the normal habits and anatomy of wild animals species.
4. Carcasses are spotted very late and often badly mutilated by scavengers in free wildlife thus making it difficult to pin point the primary cause of death.

Necropsy procedures for certain wild animals are similar to that of domestic animals as indicated below:

Necropsy procedure

Verification of the carcass: Check and verify the cadaver details such as species, breed, sex, approximate age, identification number (applicable for captive animals; if any), color etc. as mentioned in the requisition paper. The details are specifically important in veterolegal cases.

History: The history regarding the clinical symptoms, duration of the disease, mortality and morbidity pattern, age-group and sex involved, any sudden change in feed or source of feed, change in climate, involvement of single or more than one species of animals in the area with similar disease manifestations, introduction of new animal(s) in existing stock and any other relevant information regarding the disease should be obtained. It is important to record the date and time of death, if known.

External examination of the carcass: The carcass should be thoroughly inspected for general condition like appearance (good, fair, weak, cachectic or hide-bound), post-mortem stage of the carcass such as in algor mortis, rigor mortis or livor mortis which gives an approximate time elapsed after death; condition of the natural orifices (any discharge, prolapse), visible mucous membranes (normal pink, pale, red, yellowish), marks of external injury (fresh or old) or any other pathological lesions (abscess, growth,  alopecia, exudative dermatitis, mange, ectopatasites), congenital anamaly etc. The anatomical location and actual measurements of the lesion should be described in an easily understandable and non-technical language. In case where the animal has been suspected to have died of Anthrax, make smears of the peripheral blood preferably by pricking the tip of the external ear. Such cases should not be opened till the possibility of Anthrax is completely ruled out.

Before proceeding ahead, carcass weight should be recorded if weighing machine is available and body measurements like length (pole to base of tail), length of the tail, height (from sole of fore limb to point of wither), girth (body circumference passing through both axilla) and wrist circumference. Approximate age of the animal can be assessed by body appearance, horns and dentition.

Deskinning and examination of subcutaneous tissues: As a rule deskining should be done in the presence of the necropsist. The attendant is asked to deskin the caracass leaving the genital organs and udder attached in the normal position. The skin is examined on both the sides. Look for colour, condition of the fascia, amount of fat whether normal or gelatinized, hematoma (size and location), blood vessels and condition of blood (unclotted or clotted, color of blood – bright red, pale watery or chocolate). Muscles should be examined for their color (pale or deep red or yellowish tinge), texture (normal, juicy, crepitating or had necropurulent sinuses/tract particularly in large muscle of thigh or limbs).

Opening of carcass: The cadaver is supported on its back inclined toward the left side. The hind legs are abducted by cutting through the medial thigh muscles (anteroposteriorly) close to the pelvic symphysis, opening the hip joints and severing the ligaments.  Incise around the udder in female and remove it from its attachments.  In the case of male, penis along with prepuce is detached and drawn backward up to the ischial arch. The fore limbs are also separated by incising in the axilla close to the chest wall and severing the muscles attached to scapula. Dorsal attachments are not cut leaving the fore limbs partly attached with the body.

Make a superficial incision in the linea alba, taking due care for not puncturing the viscera (in cases of excessively distended and tense rumen wall due to antemortem bloat or postmortem accumulation of gases etc., a small puncture on the left abdominal wall with the point of knife is made to allow the escape of gas and relax the wall).  Extend the incision from the opening in the linea alba, guided by two fingers up to the xiphoid cartilage anteriorly and pubic symphysis posteriorly. Reflect the abdominal wall along the costal arch on either side and in female along the border of the pubic bones as well. Look for if any excessive quantity of fluid is present in the abdominal cavity. Note the colour, transparency and approximate quantity of the fluid. In case material is to be collected for bacterial or viral isolation, collect the sample first and then proceed further to avoid extraneous contamination by infected knife or from leaking ingesta from a puncture in GIT. Examine for the normal position of the viscera and note the changes, if any. The scrotum is cut to expose the testicles, incise the tunica vaginalis and    draw out the testicles with the help of scissors, cut the tunica vaginalis and separate the spermatic cord up to the inguinal level. Remove the omentum from the longitudinal grooves and examine. The anatomical locaton, positions (malpositions- torsion, volvulus, intussusception, hernia, displacement etc.,), congenital maformations, gross tumours, abscesses etc. should be noted and described in terms of location, shape, size, colour, consistency and anatomical relationship with other organs like adhesion embedding etc. at the time of removal of the organs.

• Gastrointestinal System: It starts with the examination of the buccal cavity. Entire mucosal surface of cheek, gums, tongue, and pharynx along with lips, commissures and teeth should be examined for any pathological lesion. Oesophagus is examined for changes in mucosal surface (inflammation, erosions,ulcerations), obstruction, stricture, stenosis, tumourous growth, parasitic lesions etc. Rumen is examined for the quantity and consistency of contents (thin, doughy-impaction, presence of free gas or gas bubbles trapped in ingesta-tympanites), pH, condition of the mucosa, rumen pillars, foreign bodies (polythene, rubber ball or hair balls) and parasites (mature amphistomes) etc. Reticulum of ruminants is specifically examined for presence of sharp metallic objects like nails, wire pieces etc., and adhesions with diaphragm or liver. Omasum is examined for impaction or inflammation / ulcerations of mucosal folds. Abomasum of ruminants and stomach of monogastric animals is opened from its greater cuvatuer and examined for distension, type and consistency of the contents, parasites, foreign objects like hair balls, and condition of mucosa (swollen, oedematous, inflamed, haemorrhage, ulcerated or perforated, rupture, nodules, tumourous growth etc). In pigs gastric ulcers on cardia are seen frequently,.and also for obstruction and stenosis of pylorus. Intestine (small- duodenum, jejunum and ileum; and large-caecum, colon and rectum) are examined for malpositions, obstruction, type of contents, parasites, inflammation, haemorrhage etc. The intestines are opened by scissors and examined. The contents can be viewed by a magnifying hand lens for small parasitic stages and very small nodules in the wall. Anus is examined for lacerations or prolapse. Mesenteric lymph nodes should invariably be examined along with intestines. Liver is examined for size, consistency, colour, cut surfaces by slicing the organ, condition of intrahepatic bile ducts, parasites. Gall bladder for amount , colour, consistency, transparency of bile, presence of parasites, calculi, mucosal condition-smooth, rough, inflammed, oedematous or tumourous; patency of bile duct etc. Spleen should be examined for size, consistency, weight, colour, presence of haemorrhages on surface or presence of infarcts or any other anomaly.
• Urino-genital System: Examination include kidneys for normal location, size (atrophy or hypertrophy), colour, condition of perirenal and pelvic fat, cut surface-cortex, medulla, renal pelvis for dialatation (hydronephrosis), infarcts, calculi, pus (pyelonephritis) are examined and the changes recorded. Ureters are looked for dialation in cases of hydronephrosis or pyelonephritis or for calculi. Urinary bladder is first checked for patency of the urethra by pressing the distended bladder and observing passing of urine from penile urethral opening., colour, transparency of urine, mucosal changes (smooth, rough, inflamed, haemorrhagic or with tumourous growth). Urethra particularly in the region of sigmoid flexor is the site for lodgement of calculi in bovines. Prepuce is examined particularly in pigs where due retention of urine results in bacterial growth forming ulcerative lesions. Accessory sex glands (seminal vesicles, prostate and bulbourethral), gonads (testes, ovaries) and other genital organs are similarly examined for gross changes as mentioned above.
• Respiratory System: the examination includes external nares, nasal sinuses, paranasal sinuses, larynx, trachea, bronchi, lungs and associated lymph nodes (bronchial and mediastinal). The air passages and sinuses are looked for exudates, inflammation or haemorrhage, presence of foreign bodies or parasites or any growth. Lungs are examined opening through the air passage and also incising the parenchyma. Congestion, haemorrhage, consolidation (loss of crepitation , solid & dark look with heaviness and sinking of piece in water), emphysema, atelectasia, mucus plugging, presence of parasites in terminal bronchioles, cysts, nodules or tumours may be encountered on gross examination of lungs. The changes may be described in terms of shape, size, area and involvement of lobe, type of exudates etc.
• Cardio-vascular System: Heart is examined for condition of pericardium, presence of fluid/exudates-color, consistency, amount, transparency, Epicardial surface thickness of myocardium, ventricular volume, septal or valvular defects, endocardial surface (petechae, ecchymoses), heart worms (canids and felids), large blood vessels (aorta, pulmonary vein and artery) for thrombus or intimal thickening or parasites.
• Nervous System: Brain examination include condition of meninges and their blood vessels , surface corrugations, ventricles, presence of parasitic cysts, malacic foci etc.

Necropsy procedure for snakes

1. Carefully examine oral mucosa

2. Then, decapitate in venomous snake using heavy cutting shears, keep in a special

container, incinerate or safely dispose.

3. Examine skin and scales for ulcers and mites especially in the ventral surface.
4. Then place the snake on its back, using heavy cutting shears incise through mid ventral line from anterior cervical extremity to the cloaca.
5. Reflect the skin over the side and examine subcutis and the organs in situ.
6. Open and examine the trachea and lungs
7. Examine liver, spleen and pancreas (adjacent to gall bladder).
8. Separate the alimentary tract from the mesenteric attachments using scissors or scalpel.
9. Then open and examine the alimentary tract.
10. Examine the kidneys (paired, elongate, and lying along the vertebrae from the vent forward).
11. Examine gonads (Testes: elongate, white, flat; ovary: elongate series of many ova).
12. Examine the oviduct, situated posterior to ovary. Observe whether oviparous or viviparous.
13. Examine the male copulatory organ which is paired, each hemipenis extends caudally from the cloaca.

Necropsy Procedure for Turtles

1. Place the animal on its back in a suitable concavity.
2. Open the body cavity using a saw to cut through plastron (ventral shell plate) at the junctures with carapace (dorsal shell).
3. Free soft tissues underneath plastron with flat – blade knife
4. Remove the hind limbs with saw.
5. Examine the viscera system-wise

https://www.pashudhanpraharee.com/techniques-procedure-for-post-mortem-of-elephant/

References

1. Chauhan, R.S., Singh, R. and Singh, K.P. (2007). Art of Disease Investigation including Collection, Preservation and Dispatch of Materials for Laboratory Diagnosis. PP 1-82. Director, V.R.I., Izatnagar U.P.  (India).
2. Rajan, A. and Valsala, V. (2002). Postmortem Examination. In : Handbook of Animal Husbandry. Indian Council of Agricultural Research, New Delhi, PP 1096-1119.
3. Singh, R., Singh, K.P. and Chauhan, R.S. (2007). Manual of Diagnostic Pathology. Center for Animal Disease Research and Diagnosis, I.V.R.I., Izatnagar, U.P. (India).
4. Sinha, B.K. (1994). Postmortem Techniques and Diagnostic Procedures with Interpretation. Chapter-1, PP 15-35. Pushpa Prakashan, Patna, Bihar (India).
5. W. Pritchat (1955) Description in pathology-avoiding pathological description. Arch. Path. 59:612-617
6. http://www.iucn-whsg.org/sites/default/files/Post-mortem%20procedures%20for%20wildlife%20veterinarians%20and%20field%20biologists.pdf
7. http://www.vethelplineindia.co.in/postmortem-diagnosis-and-field-veterinarians-in-india/

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