Post mortem (PM) is the procedure carried out after death to determine the cause of death. It is a specialised procedure, requiring a good knowledge of animal anatomy. The operator needs to know what normal healthy tissue looks like and this cannot be learnt from books, only from experience. The farmer should attend post mortems conducted by the vet and look at healthy tissue at abattoirs etc.
Before beginning the PM it is important to make note of place, date, owner’s name, species, number of animals affected, number of deaths, breed, sex, age, brand or tag number, hours since death and the history. The post mortem should take place as soon after death as possible. Ideally a second person should take notes as the PM progresses.
Equipment required
- Rubber boots, protective clothing, rubber apron or lab coat, rubber gloves.
- Knives – large and small, with sharpening steel.
- Scissors (various sizes) and saws; bone cutters
- A number of sterile, open-mouthed screw top jars of different sizes for specimen collection
- Formalin (40% formaldehyde)
- Sterile swabs in test tubes
- Alcohol cleaned slides for smears, preferably in a rack or box
- Spatula
- Plastic bags for specimens
- Petri dishes
- Labels
- Soap, water, disinfectant and towel.
All samples e.g. smears, slides, tissue sections, should be labeled and stored as they are taken.
Procedure
- Carefully note external abnormalities. Check orifices, genitals and mammary glands. Make note of any injuries, wounds, parasites.
- Unless you suspect anthrax or rabies lay back the skin
- Remove the udder in females and the genitals in males. Cut away the front leg by incision under the shoulder blade. Open the abdominal cavity by incision from sternum to pubes.
- Check and note whether there is peritoneal fluid in the cavity. Make note of amount and colour. Check absence or presence of fat and intestinal gas.
- Open the thoracic cavity along the diaphragm. Cut through the sternum at the centre point and saw through the upper ribs. Note whether there is fluid in the thoracic cavity and pericardial sack.
- Remove the 4 parts of the stomach in ruminants, or the stomach in non-ruminants and the spleen by cutting the oesphagus and small intestine. Before cutting, tie off the gullet and small intestine in 2 places and cut between them. This prevents gut contents from spilling into the area. Remove the rest of the alimentary canal, tying off at the rectum.
- Examine the liver in position. Make note of size, colour, shape, presence of cysts, texture etc. Note gall bladder and contents. Remove the liver and take tissue section for laboratory analysis.
- Remove and examine the kidneys. Note the amount of fat, size, consistency and colour.
- Examine the bladder and note amount and colour of urine.
- Remove the thoracic organs. The heart is removed by cutting through the large blood vessels suspending it. The lungs are removed by cutting the trachea. The heart sack is now cut open and any abnormalities noted. The lungs are examined for elasticity, colour, and texture, presence of froth or solidification.
- All other organs – tongue, pharynx, larynx, and oesophagus are removed and examined. Tissue sections may be taken for lab analysis.
- The head is sawed open and the brain and cavities of the head examined.
- Lymph nodes are examined throughout and abnormalities noted.
- The organs receiving the most attention will be those related to the disease symptoms of the animal or the disease suspected.
BEWARE !!! If you have any reason to suspect anthrax or rabies as the cause of death, or in the cases of unexplained sudden death, the carcass must never be opened. If anthrax is suspected, a blood slide taken from a cut on the ear is sent to the labs for confirmation. If rabies is suspected – the head should be removed intact and sent to the lab in a sealed container. For small animals the whole carcass can be sent.
In both cases, protective clothing, including boots, gloves, face mask and goggles must be worn. The carcasses should be burned or deep buried under stones with quick-lime.
