agriculture पशुपालन

Techniques & Procedure of Post-Mortem(PM) Examination of Animals

Post-Mortem
Written by bheru lal gaderi

Necropsy of animal carcasses is an important tool in the diagnosis of diseases and ultimately their control. It also becomes extremely relevant in addressing vetero-legal cases. Therefore, a veterinarian must have the basic knowledge of the Post-Mortem techniques, recording of lesions, their interpretation, a collection of proper sample for laboratory examination, and writing of the report.

Post-Mortem

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Necropsy examination:-

  • Post-Mortem Examination (PM) of the carcass is conducted by Veterinarian or a Veterinary Pathologist to ascertain the cause and nature of the disease in fatal cases of diseases. The term autopsy is preferred in human medicine for PM examination and necropsy in Veterinary Medicine.
  • Autopsy means seeing with one‘s own eyes. • Necropsy means seeing a carcass.
  • Autopsies are one who conducts the PM examination.

Types of necropsy

  • Where no necropsy is conducted
    o If the blood smear from ear vein (cattle, sheep, and goats) or smear from oedematous fluid from the throat or abdominal region (pings, horse) reveals anthrax bacilli no necropsy should be conducted on the carcass since the organisms are aerobic spore formers. The spores survive as long as 18 years.

S.No. Particulars Anthrax bacilli Anthracoid

  1. Organism Bacillus anthracis Other than B.anthracis
    2. Capsule Predominantly pink stained Less predominant
    3. Spores Absent Present
    4. Length of chain Short-usually 2 to 3 organisms Long chains
    5. End of bacilli Truncated Rounded

Partial necropsy

  • In case of rabies only the brain of the ‗carcass‘ is examined for diagnosis. Here only a part of the body (head) is opened for the purpose. Other parts of the body are not opened.
  • Complete necropsy of All parts of the body is thoroughly examined to arrive at an aetiological diagnosis.
  • Cosmetic necropsy of Examination of the carcass is done with very less mutilation. Cuttings and incisions are sewed together and the body is was

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Necropsy as a factor in diagnosis

shed to appear as nearly intact as possible. It is done in case of pet and wild animals.

  • Necropsy actually accomplishes to bring into open previously unseen or merely surmised lesions and even certain etiological agents not observable from the animal‘s exterior. Quite frequently, the necropsy may be compared with opening and reading a book, the title of which conveys a certain meaning; but it is the text that really portrays the plot, the sequence of events and the conclusions. The necropsy like the textbook may reveal items of a surprising or unexpected nature thus explaining previously unknown or baffling events.
  • Clinical diagnosis would be more accurate if the clinician follows the animal which failed to respond to therapy to the necropsy.
  • The veterinarian holds a district advantage over the physician in the matter of Post-Mortem diagnosis since he/she may employ euthanasia in order to hasten the process of diagnosis.

Time of necropsy:-

  • The Post-Mortem examination (PME) should be conducted as soon as possible after the death of the animal. If delayed, various PM changes including autolysis and putrefaction may set in which sometimes may confuse with morbid lesions and distort the diagnosis. However, even if PM changes have advanced considerably, still from a standpoint of gross pathology the deterioration is not as serious as many believed. If the disease was one that could have been diagnosed originally by the gross pathological changes it probably can still be diagnosed by distinguishing PM changes from morbid lesions.

Place of necropsy and site for disposal:-

  • The veterinary practitioner needs but little space for the conduct of necropsies. For small animals, a well-ventilated room of the hospital may be set aside for euthanasia and for necropsies. In large animals, the veterinarian should choose an outdoor large area least likely to allow contamination to spread.
  • Sanitary conditions and intended disposition of the carcass are factors which outweigh convenience in deciding where to perform the necropsy. If there is any possibility that the animal may have died of a contagious disease, it is imperative to avoid contamination of ground accessible to susceptible livestock or their food.
  • If the necropsy has to be performed near farm building or on the ground from which livestock is not excluded, it may be feasible to have an extremely deep bed of straw prepared on which to place the carcass. The straw absorbs the fluids and can be burned or buried afterward.
  • More frequently, it will be decided to transport the carcass to some distant field not used for livestock at least during the current year. If the animal is to be buried, a deep grave layered with lime can be dug where the carcass can be easily rolled into, to be followed by the contaminated layer of the earth.

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DISINFECTANTS AND PRECAUTIONS:-

Disinfectants:-

  • Although not effective as steam/heat sterilization, chemical disinfectants are usually employed for necropsy instruments, boots, and gloves as well as the tables and premises connected with necropsy. To be effective any such disinfection must be preceded by thorough mechanical cleaning. The commonly used chemicals are Lysol, cresol, chlorine, quaternary ammonium compounds, mercury in the form of bin-iodide combined with
    potassium iodide, iodophors, phenol etc. The choice of disinfectant to be used for the disposal of carcass where the cause of death suspected to be infectious and contagious (Anthrax) is quicklime.

Precautions:-

  • Obtain written permission from the owner before Post-Mortemexamination.
  • Request from local police is a must in vetero-legal cases
  • Conduct Post-Mortemas early as possible to avoid putrefaction.
  • Examine the smear from peripheral blood to rule out anthrax. Besides anthrax bacilli, examination of blood smear may reveal blood parasites, other bacterial and/or Post-Mortem invaders.
  • Post-Mortemexamination should be done in the daytime to appreciate the accurate changes in the color of tissues. This is not possible with artificial light.
  • Conduct Post-Mortemfar away from animal houses and farm premises and preferably in a government land to avoid litigation.
  • Obtain history, symptoms, and treatment done etc.
  • Wear gloves, mask, aprons, and gumboots to avoid contact with zoonotic agents.
  • Record the Post-Mortemfindings immediately.
  • Bury the carcass in deep ditches layered with lime. The carcass can be burnt to ashes if the incinerator is available.

Note before necropsy:-

  • Ruminants: Place the carcass on the left side to avoid the interference of rumen during the examination.
  • Horses: Place the carcass on the right side to avoid the interference of colons during the examination.

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NECROPSY TECHNIQUES AND OBSERVATIONS—

Steps in Necropsy —-

  1. Record the kind of animal and to whom it belongs.
  2. Write the precis of the case.
  3. Carry out the external examination of the carcass. Then proceed to internal examination.
  4. Secure the carcass on its back.
  5. Make an incision in the mid-ventral line from chin to anus going round about the external genitalia in male and incision is also made on the medial aspect of all legs and flay the skin.
  6. Examine the subcutaneous tissue.
  7. Open the cavities of the body. Look for exudates, transudate etc.
  8. Examine the position of the organs.
  9. Separate lungs from the heart and palpate for any abnormalities. Incise and examine the lungs.
  10. Examine the pericardial sac. Open the pericardium, examine the nature of contents.
  11. Cut through the heart and the vessels. Examine the wall and chambers for the nature of content, valves and the lumen of vessels.
  12. Examine the diaphragm.
  13. Examine the abdominal visceral organs-liver, spleen, kidneys, adrenals, pancreas before and after incising the organs.
  14. Open the bile ducts and gallbladder and examine.
  15. Divide the kidney symmetrically by longitudinal incision. Remove the capsule, examine the cortex, medulla, and pelvis.
  16. Open the mouth to examine the gum, tooth, tongue and buccal cavity. Then open and examine esophagus.
  17. Open the nasal cavity and examine. Examine the pharynx, larynx, trachea, and bronchi.
  18. Open the stomachs/forestomachs and abomasum (ruminants) and examine the nature of contents and the wall.
  19. Open the intestine. Examine the contents and the wall.
  20. Open and examine the urinary bladder for the nature of the content and the wall.
  21. Examine the genital organs.
  22. Open the skull and vertebral column to examine the brain and spinal cord.
  23. Examine the skeleton and musculature.
  24. Record the findings.
  25. Summarize the appearances found.
  26. Collect suitable materials for microbiological, histopathological, parasitological and chemical examination as required.
  27. Arrive at an etiological diagnosis based on the PM findings and the results of the materials examined.

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Points to remember while doing the post-mortem:———

Most of the veterinarians working in the field are forced to do a post-mortem examination in a hurry or with some sort of local compulsion. One should remember the following conditions:-

  1. Confirmation of death prior to post-mortem is the must.
  2. PM should not be conducted in carcass suspected to have died from anthrax (After suspecting the presence of anthrax bacilli in the blood smear from ear vein or oozing out of unclotted blood).
  3. PM should be conducted under sufficient daylight.
  4. Written consent of the owner for doing the post-mortem is a must. Requisition letter from the competent authority (e.g. Police officer not below the rank of inspector or magistrate) is particularly needed for metro legal and insurance-related cases.
  5. Recording details of animal identification (e.g. Ear tag, breed, sex, age, length, height, girth behind forelimb, the distance between horn tips) and maximum possible history (including date and time of death) prior to post-mortem is of prime importance.
  6. Post-mortem should not be done on the carcass that is completely putrefied with liquefaction of all organs.
  7. Post-mortem should be done only when the carcass is presented as the whole body (In case of drowned animals carcass is to be taken out of the water and presented for post-mortem).
  8. The carcass should be presented in its actual site as mentioned in the letter from owner/Police.
  9. In case of any scheduled or endangered animal species, due consent, information/permission should be taken from local forest officials and/or police before proceeding for post-mortem examination.
  10. Post-mortem area should be clean and the chances of environmental contamination should be minimal.
  11. All natural orifices should be closed with a towel or cotton wool soaked in a disinfectant solution before removing carcass to the place of the post-mortem examination.
  12. Handlers should protect themselves with gloves, apron, mask, cap, gumboot etc. to reduce the contaminations and infections. Movement of people to post-mortem site should be restricted.
  13. It is the duty of the veterinarians to ensure proper disposal of the carcass after post-mortem either through deep burial, incineration or rendering.

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Owner’s responsibility:-

Veterinarians should communicate following as owners responsibility:-

  • It is better for the owner to take the early decision to allow Post-Mortemexamination of his/her animals before the animal dies. It is important that he /she communicate wishes to the veterinarian early so that the necessary procedures can be scheduled rapidly, samples obtained quickly and the examination performed efficiently. Early post-mortem optimizes the chances of getting useful results.
  • The owner should be made aware of the importance of post-mortem. If an animal dies at home and a veterinarian is not available, he/she should be asked not to freeze the body. It is much better to refrigerate only. This prevents freezing artifacts which confuse the pathologist examining the tissues.
  • The owner should be educated on proper disposal of carthe cass after post-mortem.

PRECISE OF THE CASE:-

  • This includes the date of admission, ward, case number if treated in Veterinary Hospital or
    admission as carcass with the case number, date and time to death reported, date and time of
    making PM, history with symptoms, treatment details, and clinical diagnosis

EXTERNAL EXAMINATION OF THE CARCASS:-

  • Record the class of animal as bovine, equine, porcine, ovine, caprine, canine, feline etc., sex, age; if not known, assess based on teeth or ossification of bones; breed – specify the breed or record it as not-descript. descriptive marks – natural color and markings (whirls) and artificial marking-tattoo number, brand marks, tag number, wing band or leg band number etc., In vetero-legal cases, measure the distance between horns at the level of the base, midlevel and tips, and the length and direction of horns.
  • Record the condition of the body as fair (well-fed), poor, emaciated/cachectic (hide and bone condition).
  • Record rigor mortis as present or absent.
  • Natural orifices-nature of discharge-in anthrax tarry colored blood oozes from natural orifices and blood fails to clot. Abortion or metritis-discharge from the genital orifice.
  • Visible mucous membrane -Pink, pale or blanched (anemia), icteric (jaundice), congested, hemorrhagic, cyanotic (local or systemic disturbances). Skin and coat – hair loss (patchy or complete); look for the presence of wounds, abrasions, lacerations, perforations, swelling, abscess and tumors. Check umbilicus for omphalitis, mammary gland and external genitalia for any change.
  • Snakebite; Fang marks with swelling, haemorrhage necrosis; Foot and Mouth Disease vesicles, maggot wounds in the interdigital spaces; Bluetongue: coronet region congestion and haemorrhage; Swine erysipelas: diamond-like lesion; swine fever; erythema or purplish discoloration of skin; Canine distemper: pustules on the ventral side of the abdomen; Pock lesion on the udder and teats in cattle and face and also underneath the tail in sheep.
  • Examine the skin-look for dermatomycosis (ringworm) and scabies or manage and look for ectoparasites-ticks, lice, fleas etc., Examine the superficial lymph nodes – prescapular, precrural etc., swollen (theileriosis) purulent inflammation (glanders, strangles).

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INTERNAL EXAMINATION OF THE CARCASS:-

  • Subcutaneous tissue: normally fair and moist but may be dry, congested, hemorrhagic (contusions), icteric, edematous, arboriform congestion and hemorrhages (electrocution).
  • Abdominal and thoracic cavities-record the nature of exudates, if present, examine the organs in situ to appreciate any dislocation (abomasal displacement, intussusception, hernia etc.) adhesion of serous membranes etc.
  • Pericardial sac-moist, record the nature of the content -cattle -traumatic pericarditis with fibrinopurulent exudates and foreign body may be seen: cardiac tamponade-blood clot covering the heart-rupture of the aorta (spirocercosis).
  • Heart – epicardial and endocardial haemorrhage (septicaemia, toxaemia, enterotoxaemia, impaction, pyometra); purulent pericarditis in salmonellosis, fibrinous pericarditis in colisepticaemia, tigroid appearances, i.e pale streaks in myocardium in Foot and Mouth Disease in calves and pigs; Chambers may contain, unclotted blood, partially clotted blood, clotted blood ―current jelly‖ and ―chicken fat‖ clot. Vegetative endocarditis affect
    valves (swine erysipelas, streptococcal and corynebacterial infections etc.)
  • Larynx, trachea, bronchi-mucosa may be congested: trachea and bronchi contain frothy exudates in pulmonary edema, aspirated substances, caseous and haemorrhagic exudates with haemorrhagic mucosa (ILT), Lungs: pink and spongy normally, areas of emphysema, collapse, congestion, subpleural/parenchymatous haemorrhages, infarcts, red or grey hepatisation, granulomatous nodules may be caseous, calcified or uncalcified in
    contagious bovine pleuropneumonia), black spots (anthracosis), brown induration (chronic cardiac failure): pleura-shaggy appearance in serofibrinous inflammation.
  • Spleen -enlargement, infarction, abscesses, tumour (lymphoid).
  • Kidney-Capsule should peel off easily: but is adherent to cortical surface of kidney in inflammation: kidney -enlarged, shrunken and hard (chronic nephritis), cystic, hydronephrosis, congested, petechial haemorrhages (―turkey egg appearances‖ in swine fever), pale areas (infarcts or lymphoid cell collection-theileriosis), tumours; Lesions may involve medulla and pelvis; Pelvis-surface smooth, eroded, congested, calculi.
  • Ureter -distended, indurated; Gout -tortuous with urates and uric acid and distended.
  • Urinary bladder -may be empty or distended with urine, examine nature of contents [urine straw colored to colorless normally, deep yellow (icterus)], reddish to coffee colored (haematuria and hemoglobinuria); Mucosa -congested, hemorrhagic, bladder – thickened (chronic cystitis, bovine hill haematuria). Look for calculi (maybe few to many).
  • Adrenals-enlargement, tumor, thinning or widening of the cortex (stress).
  • Mouth: Look for vesicles and ulcers on the gums, dental pad, tongue etc., in the foot and mouth disease, Bran-like deposits on the gums and tongue in rinderpest, cyanotic tongue in blue tongue, wooden tongue in actinobacillosis, the condition of teeth: worn out, sharp teeth etc., and tumors.
  • Esophagus- Check patency (stenosis and dilatation or diverticulum) and for foreign bodies (choke), spirocerca nodules (distal end of the esophagus) in dogs, pustule-like lesion in vitamin A deficiency in chicken.
  • Forestomachs (ruminants) -bloat, examine nature of content-solid semisolid, liquid/watery, impacted, exudates etc., nature of exudates, worms, trichobezoars, phytobezoars and foreign bodies. Examine mucosa and submucosa for erosions, ulceration, congestion, hemorrhage, perforation etc.
  • Forestomach or stomach: Impaction and bloat -congested and hemorrhagic, vesicles in FMD; abomasums -ulcers in theileriosis; Habronema nodules in horses Ranikhet disease – proventricular hemorrhages around glandular papillae; IBD – hemorrhage in the proventriculus -gizzard junction.
  • Intestine: Coccidiosis ballooning up of the intestine with red and white spots seen through serosa with blood mixed porridge-like content present in the lumen. Rinderpest serofibrinous foul smelling contents; streaks of hemorrhages in the intestine and rectum (Zebra marking); Swine fever – buttons like ulcers in the caecum and colon. Nodules -E.coli infection, lymphoid leucosis, TB, worms; gangrenous inflammation (intussusception,
    volvulus, torsion), calculi. Mesentery: vessels for congestion, surface for deposits (Traumatic peritonitis, egg peritonitis) and tumors.
  • Liver-may become pale, yellowish (icterus, fatty changes) normal sharp borders become rounded(swelling) soft and friable(fatty changes) cooked up appearance, hard in consistency in cirrhosis/chronic hepatitis, nutmeg appearance (chronic venous congestion), surface may show congestion, necrotic foci (grayish-white), telangiectasis, haemorrhages, cysts, abscesses, tumours which may extend into parenchyma, liver flukes in bile ducts with clay-pipe cirrhosis/biliary cirrhosis, colisepticaemia-fibrinous exudates covers the
    surface.
  • Gallbladder -thickened wall, nature of the content (bile) -think, thick, greenish, yellowish
    green etc., calculi.
  • Generative organs: testicles – Cryptorchid, swelling, balanoposthitis; Accessary glands-prostate-enlargement; ovaries enlargement, cystic, and tumors, uterus -tear, torsion, congestion, hemorrhage, nature of the content, mummified or macerated fetus, pyometra (common in dogs), vagina and vulva (IBR/IPVV).
  • Skeleton: Actinomycosis -granuloma of mandibular bones: fractures, osteoporosis, osteopetrosis, osteodystrophy, rickety rosary (vitamin deficiency), Bone marrow -for hyperplastic or hypoplastic activity.
  • Musculature: degeneration, necrosis, gangrene (BQ) pale streaks (Vitamin E and Selenium deficiency, white muscle disease) and abscesses. Brain, spinal cord, and meninges for congestion, hemorrhage (heat stroke), cyst-coenurus, encephalomalacia (Vitamin E deficiency) Nature of cerebrospinal fluid -clear, cloudy etc.
  • Examine all lymph nodes in general, particularly regional lymph nodes if any changes are detected in the organs or tissues. Lymph nodes – enlarged, oedematous, congested, hemorrhagic, granulomatous (TB, JD) purulent (strangles, glanders) and tumors (lymphosarcoma). Examine bursa in birds – enlarged, hemorrhagic, contain creamy, caseous or hemorrhagic exudates and shrunken (IBD).

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NECROPAY PROFORMA OTHER THAN POULTRY:-

No. —-

POST-MORTEM REPORT —-

Notes on the Post-Mortemexamination on the body of a ___________________
belonging to ………………………………………………………………………………… The result of examination of blood smear taken after death :
A. Precis of the case

  1. Date of admission, ward, and case No.
  2. Date and time of death reported.
  3. Date and time of making P.M.
  4. History
  5. Clinical diagnosis
  6. External Examination
    1. Class of animal, sex, age, breed
    2. Descriptive marks
    3. The condition of the body
    4. Rigor mortis
    5. Natural orifices
    6. Visible mucous membranes
    7. Presence of wounds, if any
    8. Superficial lymph nodes
    9. Any other abnormalities
  7. Internal Examination
    1. Subcutaneous tissue
    2. Abdominal cavity
    1. Peritoneal cavity and peritoneum
    2. The position of organs (organs inspected in situ)
    3. Thoracic cavity
    1. The pleural cavity and pleura
    2. Position of organs
    4. Pericardial sac
    5. Heart
    1. Gross appearance, color, size etc.
    2. Chambers
    3. Valves/Endocardium
    4. Myocardium
    5. Blood vessels
    6. Larynx, Trachea, and Bronchi
    1. Abnormalities
    2. Parasites
    3. Bronchial lymph nodes
    7. Lungs
    1. Gross appearance, color, size etc.
    2. Palpable abnormalities
    3. Section
    4. Parasites
    5. L. nodes
    8. Diaphragm
    9. Liver
    1. Gross appearance, color, size etc.
    2. Surface
    3. Borders
    4. Parenchyma
    5. Portal lymph nodes
    6. Gallbladder (wall and contents)
    7. Parasites
    10. Spleen
    11. Kidneys
    1. Gross appearance, color, size etc.
    2. Capsule
    3. Cortical surface
    4. Section
    5. Renal pelvis
    6. Parasites and calculi
    12. Adrenal glands
    13. Head
    1. Mouth (lips, teeth, gums, tongue, palate, salivary gland etc. and associated lymph
    nodes)
    2. Eyes
    3. Ears
    14. Nasal cavity
    1. Mucous membrane
    2. Sinuses
    3. Pharyngeal mucous membrane
    4. Tonsils
    5. Guttural pouches
    6. Retropharyngeal lymph nodes
    15. Neck
    1. Oesophagus
    2. Thyroids
    3. Parathyroids
    4. Thymus
    16. Stomach (s) – Forestomach in ruminants
    1. Serous surface
    2. Mucosa and contents
    3. Parasites
    17. Intestines
    1. Mesentery, mesenteric blood vessels, lymph nodes and parasites
    2. Surface (serous and mucous)
    3. Ileocaecal valve
    4. Contents (Parasites)
    18. Pancreas
    19. Pelvic cavity
    1. Urinary bladder
    2. Generative organs
    3. Accessory sexual glands
    4. L. nodes
    20. Brain and spinal cord
    21. Skeleton and musculature
    22. Clinical Laboratory Examination
  8. Appearances found

Diagnosis:
Materials collected:

Result of examination:

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POULTRY POST-MORTEM REPORT

  • Name of the institution:
    • Poultry necropsy No. :
    • Date & Time of making necropsy:
    • Owner Name and Address :
    • Reference :
    • Date, time and place of death : • Particulars of the bird :
    • Species: Breed: Type of bird: Commercial/Breeder/Fancy/Wild Broiler / Layer
    • Age:
    • Sex : M/F
    • Identification / Wing /Leg band No: • Colour:
    • History:
    • Total stock:
    • Mortality :
    • Pattern for last 7 days: • Percentage :
    • Signs :

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Compiled & shared by-

Post-Mortem

DR. RAJESH KUMAR SINGH,

JAMSHEDPUR,

JHARKHAND

Mob no. – 9431309542,

Email – rajeshsinghvet@gmail.com

Post no-617 Dt-26/03/2018

 

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bheru lal gaderi

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